diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,32 @@
 # Revision history for ghcup
 
+## 0.1.18.0 -- 2022-07-30
+
+* Fix tui set wrt [#266](https://gitlab.haskell.org/haskell/ghcup-hs/-/merge_requests/266) by Arjun Kathuria
+    - Ask the user to install the tool via prompt when setting an non-installed version
+* improvements to safe (un-)installations
+    - bindists that don't support `make DESTDIR=/some/tmp/dir install` are now unsupported
+    - installed GHC files are now recorded to avoid use of `removePathForcibly`
+    - internally uses a newtype wrapper for user-input paths and restrict destructive operations to validated paths
+* Add `--disable-ld-override` for darwin bindists wrt #391
+* Allow passing bindist configure args wrt #377
+* use of `TMPDIR` is dropped... now uses an internal tmp dir `~/.ghcup/tmp`
+* improvements to error handling and warnings
+* Require --isolate to have an absolute directory, fixes #367
+* Fix mingw PATH handling wrt #371
+* Add --mingw-path switch to `ghcup run`
+* Fix `ghcup run` on windows, fixes #375
+* Improve `ghcup compile <hls|ghc>`
+    - short hashes now work
+    - print the long hash in addition to the detected version
+* Improve `ghcup compile hls`
+    - add `--git-describe-version` switch as an alternative to `--overwrite-version`
+    - Allow to build HLS from hackage (now is the default)
+	- Allow to run 'cabal update' automatically before the HLS build
+	- Fix parser and completer for 'ghcup compile hls --version'
+* Improve `ghcup compile ghc`
+    - Allow to build from arbitrary GHC source dists
+
 ## 0.1.17.10 -- 2022-05-12
 
 * windows hotfix (hackage-only release)
diff --git a/app/ghcup/BrickMain.hs b/app/ghcup/BrickMain.hs
--- a/app/ghcup/BrickMain.hs
+++ b/app/ghcup/BrickMain.hs
@@ -13,9 +13,11 @@
 import           GHCup.Types.Optics ( getDirs )
 import           GHCup.Types         hiding ( LeanAppState(..) )
 import           GHCup.Utils
-import           GHCup.Utils.Logger
-import           GHCup.Utils.Prelude ( decUTF8Safe )
-import           GHCup.Utils.File
+import           GHCup.Prelude ( decUTF8Safe )
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.Process
+import           GHCup.Prompts
 
 import           Brick
 import           Brick.Widgets.Border
@@ -44,7 +46,6 @@
 import           Data.Versions           hiding ( str )
 import           Haskus.Utils.Variant.Excepts
 import           Prelude                 hiding ( appendFile )
-import           System.Directory               ( canonicalizePath )
 import           System.FilePath
 import           System.Exit
 import           System.IO.Unsafe
@@ -52,6 +53,8 @@
 import           URI.ByteString
 
 import qualified Data.Text                     as T
+import qualified Data.Text.Lazy.Builder        as B
+import qualified Data.Text.Lazy                as L
 import qualified Graphics.Vty                  as Vty
 import qualified Data.Vector                   as V
 import System.Environment (getExecutablePath)
@@ -98,7 +101,7 @@
   [ (bQuit, const "Quit"     , halt)
   , (bInstall, const "Install"  , withIOAction install')
   , (bUninstall, const "Uninstall", withIOAction del')
-  , (bSet, const "Set"      , withIOAction ((liftIO .) . set'))
+  , (bSet, const "Set"      , withIOAction set')
   , (bChangelog, const "ChangeLog", withIOAction changelog')
   , ( bShowAllVersions
     , \BrickSettings {..} ->
@@ -437,7 +440,9 @@
               , TarDirDoesNotExist
               , FileAlreadyExistsError
               , ProcessError
-              , GHCupShadowed
+              , ToolShadowed
+              , UninstallFailed
+              , MergeFileTreeError
               ]
 
   run (do
@@ -447,7 +452,7 @@
       case lTool of
         GHC   -> do
           let vi = getVersionInfo lVer GHC dls
-          liftE $ installGHCBin lVer GHCupInternal False $> (vi, dirs, ce)
+          liftE $ installGHCBin lVer GHCupInternal False [] $> (vi, dirs, ce)
         Cabal -> do
           let vi = getVersionInfo lVer Cabal dls
           liftE $ installCabalBin lVer GHCupInternal False $> (vi, dirs, ce)
@@ -484,9 +489,12 @@
             <> "Also check the logs in ~/.ghcup/logs"
 
 
-set' :: BrickState -> (Int, ListResult) -> IO (Either String ())
-set' _ (_, ListResult {..}) = do
-  settings <- readIORef settings'
+set' :: (MonadReader AppState m, MonadIO m, MonadThrow m, MonadFail m, MonadMask m, MonadUnliftIO m)
+     => BrickState
+     -> (Int, ListResult)
+     -> m (Either String ())
+set' bs input@(_, ListResult {..}) = do
+  settings <- liftIO $ readIORef settings'
 
   let run =
         flip runReaderT settings
@@ -502,9 +510,30 @@
     )
     >>= \case
           VRight _ -> pure $ Right ()
-          VLeft  e -> pure $ Left (prettyShow e)
+          VLeft  e -> case e of
+            (V (NotInstalled tool _)) -> do
+              promptAnswer <- getUserPromptResponse userPrompt
+              case promptAnswer of
+                PromptYes -> do
+                  res <- install' bs input
+                  case res of
+                    (Left err) -> pure $ Left err
+                    (Right _) -> do
+                      logInfo "Setting now..."
+                      set' bs input
 
+                PromptNo -> pure $ Left (prettyShow e)
+              where
+                userPrompt = L.toStrict . B.toLazyText . B.fromString $
+                  "This Version of "
+                  <> show tool
+                  <> " you are trying to set is not installed.\n"
+                  <> "Would you like to install it first? [Y/N]: "
 
+            _ -> pure $ Left (prettyShow e)
+
+
+
 del' :: (MonadReader AppState m, MonadIO m, MonadFail m, MonadMask m, MonadUnliftIO m)
      => BrickState
      -> (Int, ListResult)
@@ -512,7 +541,7 @@
 del' _ (_, ListResult {..}) = do
   AppState { ghcupInfo = GHCupInfo { _ghcupDownloads = dls }} <- ask
 
-  let run = runE @'[NotInstalled]
+  let run = runE @'[NotInstalled, UninstallFailed]
 
   run (do
       let vi = getVersionInfo lVer lTool dls
diff --git a/app/ghcup/GHCup/OptParse/ChangeLog.hs b/app/ghcup/GHCup/OptParse/ChangeLog.hs
--- a/app/ghcup/GHCup/OptParse/ChangeLog.hs
+++ b/app/ghcup/GHCup/OptParse/ChangeLog.hs
@@ -12,9 +12,11 @@
 
 
 import           GHCup.Types
-import           GHCup.Utils.Logger
 import           GHCup.OptParse.Common
-import           GHCup.Utils.String.QQ
+import           GHCup.Prelude
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
+import           GHCup.Prelude.Process (exec)
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -34,8 +36,6 @@
 import GHCup.Utils
 import Data.Versions
 import URI.ByteString (serializeURIRef')
-import GHCup.Utils.Prelude
-import GHCup.Utils.File (exec)
 import Data.Char (toLower)
 
 
@@ -58,7 +58,7 @@
     --[ Parsers ]--
     ---------------
 
-          
+
 changelogP :: Parser ChangeLogOptions
 changelogP =
   (\x y -> ChangeLogOptions x y)
@@ -71,15 +71,16 @@
                 "cabal" -> Right Cabal
                 "ghcup" -> Right GHCup
                 "stack" -> Right Stack
+                "hls"   -> Right HLS
                 e       -> Left e
               )
             )
-            (short 't' <> long "tool" <> metavar "<ghc|cabal|ghcup>" <> help
+            (short 't' <> long "tool" <> metavar "<ghc|cabal|hls|ghcup>" <> help
               "Open changelog for given tool (default: ghc)"
               <> completer toolCompleter
             )
           )
-    <*> optional (toolVersionArgument Nothing Nothing)
+    <*> optional (toolVersionTagArgument Nothing Nothing)
 
 
 
@@ -116,7 +117,8 @@
       ver' = maybe
         (Right Latest)
         (\case
-          ToolVersion tv -> Left (_tvVersion tv) -- FIXME: ugly sharing of ToolVersion
+          GHCVersion tv  -> Left (_tvVersion tv)
+          ToolVersion tv -> Left tv
           ToolTag     t  -> Right t
         )
         clToolVer
diff --git a/app/ghcup/GHCup/OptParse/Common.hs b/app/ghcup/GHCup/OptParse/Common.hs
--- a/app/ghcup/GHCup/OptParse/Common.hs
+++ b/app/ghcup/GHCup/OptParse/Common.hs
@@ -16,10 +16,10 @@
 import           GHCup.Types
 import           GHCup.Types.Optics
 import           GHCup.Utils
-import           GHCup.Utils.File
-import           GHCup.Utils.Logger
-import           GHCup.Utils.MegaParsec
-import           GHCup.Utils.Prelude
+import           GHCup.Prelude
+import           GHCup.Prelude.Process
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.MegaParsec
 
 import           Control.DeepSeq
 import           Control.Concurrent
@@ -52,7 +52,6 @@
 import           Options.Applicative     hiding ( style )
 import           Prelude                 hiding ( appendFile )
 import           Safe
-import           System.Directory
 import           System.Process                  ( readProcess )
 import           System.FilePath
 import           Text.HTML.TagSoup       hiding ( Tag )
@@ -71,20 +70,24 @@
     --[ Types ]--
     -------------
 
-data ToolVersion = ToolVersion GHCTargetVersion -- target is ignored for cabal
+data ToolVersion = GHCVersion GHCTargetVersion
+                 | ToolVersion Version
                  | ToolTag Tag
 
 -- a superset of ToolVersion
-data SetToolVersion = SetToolVersion GHCTargetVersion
+data SetToolVersion = SetGHCVersion GHCTargetVersion
+                    | SetToolVersion Version
                     | SetToolTag Tag
                     | SetRecommended
                     | SetNext
 
 prettyToolVer :: ToolVersion -> String
-prettyToolVer (ToolVersion v') = T.unpack $ tVerToText v'
+prettyToolVer (GHCVersion v') = T.unpack $ tVerToText v'
+prettyToolVer (ToolVersion v') = T.unpack $ prettyVer v'
 prettyToolVer (ToolTag t) = show t
 
 toSetToolVer :: Maybe ToolVersion -> SetToolVersion
+toSetToolVer (Just (GHCVersion v')) = SetGHCVersion v'
 toSetToolVer (Just (ToolVersion v')) = SetToolVersion v'
 toSetToolVer (Just (ToolTag t')) = SetToolTag t'
 toSetToolVer Nothing = SetRecommended
@@ -97,10 +100,9 @@
     --------------
 
 
--- | same as toolVersionParser, except as an argument.
-toolVersionArgument :: Maybe ListCriteria -> Maybe Tool -> Parser ToolVersion
-toolVersionArgument criteria tool =
-  argument (eitherReader toolVersionEither)
+toolVersionTagArgument :: Maybe ListCriteria -> Maybe Tool -> Parser ToolVersion
+toolVersionTagArgument criteria tool =
+  argument (eitherReader (parser tool))
     (metavar (mv tool)
     <> completer (tagCompleter (fromMaybe GHC tool) [])
     <> foldMap (completer . versionCompleter criteria) tool)
@@ -109,20 +111,19 @@
   mv (Just HLS) = "HLS_VERSION|TAG"
   mv _          = "VERSION|TAG"
 
+  parser (Just GHC) = ghcVersionTagEither
+  parser Nothing    = ghcVersionTagEither
+  parser _          = toolVersionTagEither
 
-versionParser :: Parser GHCTargetVersion
-versionParser = option
-  (eitherReader tVersionEither)
-  (short 'v' <> long "version" <> metavar "VERSION" <> help "The target version"
-  )
 
 versionParser' :: Maybe ListCriteria -> Maybe Tool -> Parser Version
 versionParser' criteria tool = argument
   (eitherReader (first show . version . T.pack))
   (metavar "VERSION"  <> foldMap (completer . versionCompleter criteria) tool)
 
-versionArgument :: Maybe ListCriteria -> Maybe Tool -> Parser GHCTargetVersion
-versionArgument criteria tool = argument (eitherReader tVersionEither) (metavar "VERSION" <> foldMap (completer . versionCompleter criteria) tool)
+ghcVersionArgument :: Maybe ListCriteria -> Maybe Tool -> Parser GHCTargetVersion
+ghcVersionArgument criteria tool = argument (eitherReader ghcVersionEither)
+                                            (metavar "VERSION" <> foldMap (completer . versionCompleter criteria) tool)
 
 
 -- https://github.com/pcapriotti/optparse-applicative/issues/148
@@ -227,14 +228,20 @@
               False -> Left "Please enter a valid absolute filepath."
 
 isolateParser :: FilePath -> Either String FilePath
-isolateParser f = case isValid f of
+isolateParser f = case isValid f && isAbsolute f of
               True -> Right $ normalise f
               False -> Left "Please enter a valid filepath for isolate dir."
 
-toolVersionEither :: String -> Either String ToolVersion
-toolVersionEither s' =
-  second ToolTag (tagEither s') <|> second ToolVersion (tVersionEither s')
+-- this accepts cross prefix
+ghcVersionTagEither :: String -> Either String ToolVersion
+ghcVersionTagEither s' =
+  second ToolTag (tagEither s') <|> second GHCVersion (ghcVersionEither s')
 
+-- this ignores cross prefix
+toolVersionTagEither :: String -> Either String ToolVersion
+toolVersionTagEither s' =
+  second ToolTag (tagEither s') <|> second ToolVersion (toolVersionEither s')
+
 tagEither :: String -> Either String Tag
 tagEither s' = case fmap toLower s' of
   "recommended" -> Right Recommended
@@ -245,11 +252,15 @@
   other         -> Left $ "Unknown tag " <> other
 
 
-tVersionEither :: String -> Either String GHCTargetVersion
-tVersionEither =
+ghcVersionEither :: String -> Either String GHCTargetVersion
+ghcVersionEither =
   first (const "Not a valid version") . MP.parse ghcTargetVerP "" . T.pack
 
+toolVersionEither :: String -> Either String Version
+toolVersionEither =
+  first (const "Not a valid version") . MP.parse version' "" . T.pack
 
+
 toolParser :: String -> Either String Tool
 toolParser s' | t == T.pack "ghc"   = Right GHC
               | t == T.pack "cabal" = Right Cabal
@@ -441,9 +452,11 @@
       pure $ nub $ (add ++) $ fmap tagToString allTags
     VLeft _ -> pure  (nub $ ["recommended", "latest"] ++ add)
 
-
 versionCompleter :: Maybe ListCriteria -> Tool -> Completer
-versionCompleter criteria tool = listIOCompleter $ do
+versionCompleter criteria tool = versionCompleter' criteria tool (const True)
+
+versionCompleter' :: Maybe ListCriteria -> Tool -> (Version -> Bool) -> Completer
+versionCompleter' criteria tool filter' = listIOCompleter $ do
   dirs' <- liftIO getAllDirs
   let loggerConfig = LoggerConfig
         { lcPrintDebug   = False
@@ -472,7 +485,7 @@
           runEnv = flip runReaderT appState
 
       installedVersions <- runEnv $ listVersions (Just tool) criteria
-      return $ T.unpack . prettyVer . lVer <$> installedVersions
+      return $ fmap (T.unpack . prettyVer) . filter filter' . fmap lVer $ installedVersions
 
 
 toolDlCompleter :: Tool -> Completer
@@ -664,7 +677,7 @@
   GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
   bimap mkTVer Just <$> getRecommended dls tool
     ?? TagNotFound Recommended tool
-fromVersion' (SetToolVersion v) tool = do
+fromVersion' (SetGHCVersion v) tool = do
   GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
   let vi = getVersionInfo (_tvVersion v) tool dls
   case pvp $ prettyVer (_tvVersion v) of -- need to be strict here
@@ -676,6 +689,18 @@
           when (v' /= _tvVersion v) $ lift $ logWarn ("Assuming you meant version " <> prettyVer v')
           pure (GHCTargetVersion (_tvTarget v) v', Just vi')
         Nothing -> pure (v, vi)
+fromVersion' (SetToolVersion v) tool = do
+  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
+  let vi = getVersionInfo v tool dls
+  case pvp $ prettyVer v of -- need to be strict here
+    Left _ -> pure (mkTVer v, vi)
+    Right pvpIn ->
+      lift (getLatestToolFor tool pvpIn dls) >>= \case
+        Just (pvp_, vi') -> do
+          v' <- lift $ pvpToVersion pvp_ ""
+          when (v' /= v) $ lift $ logWarn ("Assuming you meant version " <> prettyVer v')
+          pure (GHCTargetVersion mempty v', Just vi')
+        Nothing -> pure (mkTVer v, vi)
 fromVersion' (SetToolTag Latest) tool = do
   GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
   bimap mkTVer Just <$> getLatest dls tool ?? TagNotFound Latest tool
diff --git a/app/ghcup/GHCup/OptParse/Compile.hs b/app/ghcup/GHCup/OptParse/Compile.hs
--- a/app/ghcup/GHCup/OptParse/Compile.hs
+++ b/app/ghcup/GHCup/OptParse/Compile.hs
@@ -12,14 +12,15 @@
 
 
 import           GHCup
+import qualified GHCup.GHC as GHC
+import qualified GHCup.HLS as HLS
 import           GHCup.Errors
-import           GHCup.Utils.File
 import           GHCup.Types
 import           GHCup.Types.Optics
 import           GHCup.Utils
-import           GHCup.Utils.Logger
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 import           GHCup.OptParse.Common
-import           GHCup.Utils.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -31,7 +32,8 @@
 import           Data.Bifunctor
 import           Data.Functor
 import           Data.Maybe
-import           Data.Versions                  ( Version, prettyVer, version )
+import           Data.Versions                  ( Version, prettyVer, version, pvp )
+import qualified Data.Versions as V
 import           Data.Text                      ( Text )
 import           Haskus.Utils.Variant.Excepts
 import           Options.Applicative     hiding ( style )
@@ -42,7 +44,7 @@
 
 import           URI.ByteString          hiding ( uriParser )
 import qualified Data.Text                     as T
-import Control.Exception.Safe (MonadMask)
+import Control.Exception.Safe (MonadMask, displayException)
 import System.FilePath (isPathSeparator)
 import Text.Read (readEither)
 
@@ -65,7 +67,7 @@
 
 
 data GHCCompileOptions = GHCCompileOptions
-  { targetGhc    :: Either Version GitBranch
+  { targetGhc    :: GHC.GHCVer Version
   , bootstrapGhc :: Either Version FilePath
   , jobs         :: Maybe Int
   , buildConfig  :: Maybe FilePath
@@ -79,11 +81,13 @@
   , isolateDir   :: Maybe FilePath
   }
 
+
 data HLSCompileOptions = HLSCompileOptions
-  { targetHLS    :: Either Version GitBranch
+  { targetHLS    :: HLS.HLSVer
   , jobs         :: Maybe Int
   , setCompile   :: Bool
-  , ovewrwiteVer :: Maybe Version
+  , updateCabal  :: Bool
+  , ovewrwiteVer :: Either Bool Version
   , isolateDir   :: Maybe FilePath
   , cabalProject :: Maybe (Either FilePath URI)
   , cabalProjectLocal :: Maybe URI
@@ -146,20 +150,22 @@
 
   compileHLSFooter = [s|Discussion:
   Compiles and installs the specified HLS version.
-  The last argument is a list of GHC versions to compile for.
+  The --ghc arguments are necessary to specify which GHC version to build for/against.
   These need to be available in PATH prior to compilation.
 
 Examples:
-  # compile 1.4.0 for ghc 8.10.5 and 8.10.7
-  ghcup compile hls -v 1.4.0 -j 12 --ghc 8.10.5 --ghc 8.10.7
-  # compile from master for ghc 8.10.7, linking everything dynamically
-  ghcup compile hls -g master -j 12 --ghc 8.10.7 -- --ghc-options='-dynamic'|]
+  # compile 1.7.0.0 from hackage for 8.10.7, running 'cabal update' before the build
+  ghcup compile hls --version 1.7.0.0 --ghc 8.10.7 --cabal-update
+  # compile from master for ghc 9.2.3 using 'git describe' to name the binary and ignore the pinned index state
+  ghcup compile hls -g master --git-describe-version --ghc 9.2.3 -- --index-state=@(date '+%s')
+  # compile a specific commit for ghc 9.2.3 and set a specifc version for the binary name
+  ghcup compile hls -g a32db0b -o 1.7.0.0-p1 --ghc 9.2.3|]
 
 
 ghcCompileOpts :: Parser GHCCompileOptions
 ghcCompileOpts =
   GHCCompileOptions
-    <$> ((Left <$> option
+    <$> ((GHC.SourceDist <$> option
           (eitherReader
             (first (const "Not a valid version") . version . T.pack)
           )
@@ -168,7 +174,7 @@
             <> (completer $ versionCompleter Nothing GHC)
           )
           ) <|>
-          (Right <$> (GitBranch <$> option
+          (GHC.GitDist <$> (GitBranch <$> option
           str
           (short 'g' <> long "git-ref" <> metavar "GIT_REFERENCE" <> help
             "The git commit/branch/ref to build from"
@@ -177,7 +183,18 @@
             short 'r' <> long "repository" <> metavar "GIT_REPOSITORY" <> help "The git repository to build from (defaults to GHC upstream)"
             <> completer (gitFileUri ["https://gitlab.haskell.org/ghc/ghc.git"])
             ))
-          )))
+          ))
+          <|>
+          (
+           GHC.RemoteDist <$> (option
+            (eitherReader uriParser)
+            (long "remote-source-dist" <> metavar "URI" <> help
+              "URI (https/http/file) to a GHC source distribution"
+              <> completer fileUri
+            )
+          )
+          )
+          )
     <*> option
           (eitherReader
             (\x ->
@@ -233,7 +250,7 @@
               "Build cross-compiler for this platform"
             )
           )
-    <*> many (argument str (metavar "CONFIGURE_ARGS" <> help "Additional arguments to configure, prefix with '-- ' (longopts)"))
+    <*> many (argument str (metavar "CONFIGURE_ARGS" <> help "Additional arguments to compile configure, prefix with '-- ' (longopts)"))
     <*> fmap (fromMaybe False) (invertableSwitch "set" Nothing False (help "Set as active version after install"))
     <*> optional
           (option
@@ -269,24 +286,46 @@
 hlsCompileOpts :: Parser HLSCompileOptions
 hlsCompileOpts =
   HLSCompileOptions
-    <$> ((Left <$> option
+    <$> ((HLS.HackageDist <$> option
           (eitherReader
-            (first (const "Not a valid version") . version . T.pack)
+            ((>>= first displayException . V.version . V.prettyPVP) . first (const "Not a valid PVP version") . pvp . T.pack)
           )
           (short 'v' <> long "version" <> metavar "VERSION" <> help
-            "The tool version to compile"
-            <> (completer $ versionCompleter Nothing HLS)
+            "The version to compile (pulled from hackage)"
+            <> (completer $ versionCompleter' Nothing HLS (either (const False) (const True) . V.pvp . V.prettyVer))
           )
-          ) <|>
-          (Right <$> (GitBranch <$> option
+          )
+          <|>
+          (HLS.GitDist <$> (GitBranch <$> option
           str
           (short 'g' <> long "git-ref" <> metavar "GIT_REFERENCE" <> help
-            "The git commit/branch/ref to build from"
+            "The git commit/branch/ref to build from (accepts anything 'git checkout' accepts)"
           ) <*>
           optional (option str (short 'r' <> long "repository" <> metavar "GIT_REPOSITORY" <> help "The git repository to build from (defaults to HLS upstream)"
             <> completer (gitFileUri ["https://github.com/haskell/haskell-language-server.git"])
           ))
-          )))
+          ))
+          <|>
+          (HLS.SourceDist <$> (option
+            (eitherReader
+              (first (const "Not a valid version") . version . T.pack)
+            )
+          (long "source-dist" <> metavar "VERSION" <> help
+            "The version to compile (pulled from packaged git sources)"
+            <> (completer $ versionCompleter Nothing HLS)
+          )
+          ))
+          <|>
+          (
+           HLS.RemoteDist <$> (option
+            (eitherReader uriParser)
+            (long "remote-source-dist" <> metavar "URI" <> help
+              "URI (https/http/file) to a HLS source distribution"
+              <> completer fileUri
+            )
+          )
+          )
+          )
     <*> optional
           (option
             (eitherReader (readEither @Int))
@@ -296,8 +335,10 @@
             )
           )
     <*> fmap (fromMaybe True) (invertableSwitch "set" Nothing True (help "Don't set as active version after install"))
-    <*> optional
-          (option
+    <*> switch (long "cabal-update" <> help "Run 'cabal update' before the build")
+    <*>
+         (
+          (Right <$> option
             (eitherReader
               (first (const "Not a valid version") . version . T.pack)
             )
@@ -306,6 +347,14 @@
             <> (completer $ versionCompleter Nothing HLS)
             )
           )
+          <|>
+          (Left <$> (switch
+                      (long "git-describe-version"
+                         <> help "Use the output of 'git describe' (if building from git) as the VERSION component of the installed binary."
+                      )
+                    )
+          )
+          )
     <*> optional
           (option
             (eitherReader isolateParser)
@@ -352,7 +401,7 @@
           )
         )
     <*> some (
-          option (eitherReader toolVersionEither)
+          option (eitherReader ghcVersionTagEither)
             (  long "ghc" <> metavar "GHC_VERSION|TAG" <> help "For which GHC version to compile for (can be specified multiple times)"
             <> completer (tagCompleter GHC [])
             <> completer (versionCompleter Nothing GHC))
@@ -388,6 +437,8 @@
                   , ProcessError
                   , CopyError
                   , BuildFailed
+                  , UninstallFailed
+                  , MergeFileTreeError
                   ]
 type HLSEffects = '[ AlreadyInstalled
                   , BuildFailed
@@ -406,6 +457,8 @@
                   , NotInstalled
                   , DirNotEmpty
                   , ArchiveResult
+                  , UninstallFailed
+                  , MergeFileTreeError
                   ]
 
 
@@ -454,7 +507,7 @@
     (CompileHLS HLSCompileOptions { .. }) -> do
       runCompileHLS runAppState (do
         case targetHLS of
-          Left targetVer -> do
+          HLS.SourceDist targetVer -> do
             GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
             let vi = getVersionInfo targetVer HLS dls
             forM_ (_viPreCompile =<< vi) $ \msg -> do
@@ -462,7 +515,7 @@
               lift $ logInfo
                 "...waiting for 5 seconds, you can still abort..."
               liftIO $ threadDelay 5000000 -- for compilation, give the user a sec to intervene
-          Right _ -> pure ()
+          _ -> pure ()
         ghcs <- liftE $ forM targetGHCs (\ghc -> fmap (_tvVersion . fst) . fromVersion (Just ghc) $ GHC)
         targetVer <- liftE $ compileHLS
                     targetHLS
@@ -472,6 +525,7 @@
                     (maybe GHCupInternal IsolateDir isolateDir)
                     cabalProject
                     cabalProjectLocal
+                    updateCabal
                     patches
                     cabalArgs
         GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
@@ -492,7 +546,7 @@
                 case keepDirs settings of
                   Never -> runLogger $ logError $ T.pack $ prettyShow err
                   _ -> runLogger (logError $ T.pack (prettyShow err) <> "\n" <>
-                        "Check the logs at " <> T.pack logsDir <> " and the build directory "
+                        "Check the logs at " <> T.pack (fromGHCupPath logsDir) <> " and the build directory "
                         <> T.pack tmpdir <> " for more clues." <> "\n" <>
                         "Make sure to clean up " <> T.pack tmpdir <> " afterwards.")
                 pure $ ExitFailure 9
@@ -505,7 +559,7 @@
     (CompileGHC GHCCompileOptions {..}) ->
       runCompileGHC runAppState (do
         case targetGhc of
-          Left targetVer -> do
+          GHC.SourceDist targetVer -> do
             GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
             let vi = getVersionInfo targetVer GHC dls
             forM_ (_viPreCompile =<< vi) $ \msg -> do
@@ -513,9 +567,12 @@
               lift $ logInfo
                 "...waiting for 5 seconds, you can still abort..."
               liftIO $ threadDelay 5000000 -- for compilation, give the user a sec to intervene
-          Right _ -> pure ()
+          _ -> pure ()
         targetVer <- liftE $ compileGHC
-                    (first (GHCTargetVersion crossTarget) targetGhc)
+                    ((\case
+                        GHC.SourceDist v -> GHC.SourceDist $ GHCTargetVersion crossTarget v
+                        GHC.GitDist g -> GHC.GitDist g
+                        GHC.RemoteDist r -> GHC.RemoteDist r) targetGhc)
                     ovewrwiteVer
                     bootstrapGhc
                     jobs
@@ -551,7 +608,7 @@
                 case keepDirs settings of
                   Never -> runLogger $ logError $ T.pack $ prettyShow err
                   _ -> runLogger (logError $ T.pack (prettyShow err) <> "\n" <>
-                        "Check the logs at " <> T.pack logsDir <> " and the build directory "
+                        "Check the logs at " <> T.pack (fromGHCupPath logsDir) <> " and the build directory "
                         <> T.pack tmpdir <> " for more clues." <> "\n" <>
                         "Make sure to clean up " <> T.pack tmpdir <> " afterwards.")
                 pure $ ExitFailure 9
diff --git a/app/ghcup/GHCup/OptParse/Config.hs b/app/ghcup/GHCup/OptParse/Config.hs
--- a/app/ghcup/GHCup/OptParse/Config.hs
+++ b/app/ghcup/GHCup/OptParse/Config.hs
@@ -7,7 +7,6 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE DuplicateRecordFields #-}
 {-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE ExplicitForAll #-}
 
 module GHCup.OptParse.Config where
 
@@ -15,9 +14,9 @@
 import           GHCup.Errors
 import           GHCup.Types
 import           GHCup.Utils
-import           GHCup.Utils.Prelude
-import           GHCup.Utils.Logger
-import           GHCup.Utils.String.QQ
+import           GHCup.Prelude
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 import           GHCup.OptParse.Common
 
 #if !MIN_VERSION_base(4,13,0)
diff --git a/app/ghcup/GHCup/OptParse/DInfo.hs b/app/ghcup/GHCup/OptParse/DInfo.hs
--- a/app/ghcup/GHCup/OptParse/DInfo.hs
+++ b/app/ghcup/GHCup/OptParse/DInfo.hs
@@ -17,9 +17,10 @@
 import           GHCup.Errors
 import           GHCup.Version
 import           GHCup.Types
-import           GHCup.Utils.Prelude
 import           GHCup.Utils.Dirs
-import           GHCup.Utils.Logger
+import           GHCup.Prelude
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.Process
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -36,7 +37,6 @@
 
 import qualified Data.Text                     as T
 import Control.Exception.Safe (MonadMask)
-import GHCup.Utils.File
 import Language.Haskell.TH
 
 
diff --git a/app/ghcup/GHCup/OptParse/GC.hs b/app/ghcup/GHCup/OptParse/GC.hs
--- a/app/ghcup/GHCup/OptParse/GC.hs
+++ b/app/ghcup/GHCup/OptParse/GC.hs
@@ -14,8 +14,8 @@
 import           GHCup
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Utils.Logger
-import           GHCup.Utils.String.QQ
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -56,26 +56,26 @@
     --[ Parsers ]--
     ---------------
 
-          
+
 gcP :: Parser GCOptions
 gcP =
   GCOptions
-  <$> 
+  <$>
     switch
       (short 'o' <> long "ghc-old" <> help "Remove GHC versions marked as 'old'")
-  <*> 
+  <*>
     switch
       (short 'p' <> long "profiling-libs" <> help "Remove profiling libs of GHC versions")
-  <*> 
+  <*>
     switch
       (short 's' <> long "share-dir" <> help "Remove GHC share directories (documentation)")
-  <*> 
+  <*>
     switch
       (short 'h' <> long "hls-no-ghc" <> help "Remove HLS versions that don't have a corresponding installed GHC version")
-  <*> 
+  <*>
     switch
       (short 'c' <> long "cache" <> help "GC the GHCup cache")
-  <*> 
+  <*>
     switch
       (short 't' <> long "tmpdirs" <> help "Remove tmpdir leftovers")
 
@@ -98,7 +98,7 @@
     ---------------------------
 
 
-type GCEffects = '[ NotInstalled ]
+type GCEffects = '[ NotInstalled, UninstallFailed ]
 
 
 runGC :: MonadUnliftIO m
@@ -129,7 +129,7 @@
    -> (ReaderT LeanAppState m () -> m ())
    -> m ExitCode
 gc GCOptions{..} runAppState runLogger = runGC runAppState (do
-  when gcOldGHC rmOldGHC
+  when gcOldGHC (liftE rmOldGHC)
   lift $ when gcProfilingLibs rmProfilingLibs
   lift $ when gcShareDir rmShareDir
   liftE $ when gcHLSNoGHC rmHLSNoGHC
diff --git a/app/ghcup/GHCup/OptParse/Install.hs b/app/ghcup/GHCup/OptParse/Install.hs
--- a/app/ghcup/GHCup/OptParse/Install.hs
+++ b/app/ghcup/GHCup/OptParse/Install.hs
@@ -7,6 +7,7 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE DuplicateRecordFields #-}
 {-# LANGUAGE ViewPatterns      #-}
+{-# LANGUAGE TypeOperators     #-}
 
 module GHCup.OptParse.Install where
 
@@ -18,8 +19,10 @@
 import           GHCup
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Utils.Logger
-import           GHCup.Utils.String.QQ
+import           GHCup.Utils.Dirs
+import           GHCup.Prelude
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 
 import           Codec.Archive
 #if !MIN_VERSION_base(4,13,0)
@@ -30,7 +33,6 @@
 import           Data.Either
 import           Data.Functor
 import           Data.Maybe
-import           Data.Versions           hiding ( str )
 import           Haskus.Utils.Variant.Excepts
 import           Options.Applicative     hiding ( style )
 import           Options.Applicative.Help.Pretty ( text )
@@ -69,6 +71,7 @@
   , instSet      :: Bool
   , isolateDir   :: Maybe FilePath
   , forceInstall :: Bool
+  , addConfArgs  :: [T.Text]
   }
 
 
@@ -193,7 +196,7 @@
                       <> completer (toolDlCompleter (fromMaybe GHC tool))
                     )
                   )
-            <*> (Just <$> toolVersionArgument Nothing tool)
+            <*> (Just <$> toolVersionTagArgument Nothing tool)
             )
         <|> pure (Nothing, Nothing)
         )
@@ -211,6 +214,7 @@
           )
     <*> switch
           (short 'f' <> long "force" <> help "Force install (THIS IS UNSAFE, only use it in Dockerfiles or CI)")
+    <*> many (argument str (metavar "CONFIGURE_ARGS" <> help "Additional arguments to bindist configure, prefix with '-- ' (longopts)"))
  where
   setDefault = case tool of
     Nothing  -> False
@@ -257,48 +261,9 @@
                        , NoToolVersionSet
                        , FileAlreadyExistsError
                        , ProcessError
-
-                       , (AlreadyInstalled, ())
-                       , (UnknownArchive, ())
-                       , (ArchiveResult, ())
-                       , (FileDoesNotExistError, ())
-                       , (CopyError, ())
-                       , (NotInstalled, ())
-                       , (DirNotEmpty, ())
-                       , (NoDownload, ())
-                       , (NotInstalled, ())
-                       , (BuildFailed, ())
-                       , (TagNotFound, ())
-                       , (DigestError, ())
-                       , (GPGError, ())
-                       , (DownloadFailed, ())
-                       , (TarDirDoesNotExist, ())
-                       , (NextVerNotFound, ())
-                       , (NoToolVersionSet, ())
-                       , (FileAlreadyExistsError, ())
-                       , (ProcessError, ())
-
-                       , (AlreadyInstalled, NotInstalled)
-                       , (UnknownArchive, NotInstalled)
-                       , (ArchiveResult, NotInstalled)
-                       , (FileDoesNotExistError, NotInstalled)
-                       , (CopyError, NotInstalled)
-                       , (NotInstalled, NotInstalled)
-                       , (DirNotEmpty, NotInstalled)
-                       , (NoDownload, NotInstalled)
-                       , (NotInstalled, NotInstalled)
-                       , (BuildFailed, NotInstalled)
-                       , (TagNotFound, NotInstalled)
-                       , (DigestError, NotInstalled)
-                       , (GPGError, NotInstalled)
-                       , (DownloadFailed, NotInstalled)
-                       , (TarDirDoesNotExist, NotInstalled)
-                       , (NextVerNotFound, NotInstalled)
-                       , (NoToolVersionSet, NotInstalled)
-                       , (FileAlreadyExistsError, NotInstalled)
-                       , (ProcessError, NotInstalled)
-
-                       , ((), NotInstalled)
+                       , UninstallFailed
+                       , MergeFileTreeError
+                       , InstallSetError
                        ]
 
 
@@ -313,52 +278,27 @@
     @InstallEffects
 
 
-type InstallGHCEffects = '[ TagNotFound
-                          , NextVerNotFound
-                          , NoToolVersionSet
+type InstallGHCEffects = '[ AlreadyInstalled
+                          , ArchiveResult
                           , BuildFailed
+                          , CopyError
+                          , DigestError
                           , DirNotEmpty
-                          , AlreadyInstalled
-
-                          , (AlreadyInstalled, NotInstalled)
-                          , (UnknownArchive, NotInstalled)
-                          , (ArchiveResult, NotInstalled)
-                          , (FileDoesNotExistError, NotInstalled)
-                          , (CopyError, NotInstalled)
-                          , (NotInstalled, NotInstalled)
-                          , (DirNotEmpty, NotInstalled)
-                          , (NoDownload, NotInstalled)
-                          , (BuildFailed, NotInstalled)
-                          , (TagNotFound, NotInstalled)
-                          , (DigestError, NotInstalled)
-                          , (GPGError, NotInstalled)
-                          , (DownloadFailed, NotInstalled)
-                          , (TarDirDoesNotExist, NotInstalled)
-                          , (NextVerNotFound, NotInstalled)
-                          , (NoToolVersionSet, NotInstalled)
-                          , (FileAlreadyExistsError, NotInstalled)
-                          , (ProcessError, NotInstalled)
-
-                          , (AlreadyInstalled, ())
-                          , (UnknownArchive, ())
-                          , (ArchiveResult, ())
-                          , (FileDoesNotExistError, ())
-                          , (CopyError, ())
-                          , (NotInstalled, ())
-                          , (DirNotEmpty, ())
-                          , (NoDownload, ())
-                          , (BuildFailed, ())
-                          , (TagNotFound, ())
-                          , (DigestError, ())
-                          , (GPGError, ())
-                          , (DownloadFailed, ())
-                          , (TarDirDoesNotExist, ())
-                          , (NextVerNotFound, ())
-                          , (NoToolVersionSet, ())
-                          , (FileAlreadyExistsError, ())
-                          , (ProcessError, ())
-
-                          , ((), NotInstalled)
+                          , DownloadFailed
+                          , FileAlreadyExistsError
+                          , FileDoesNotExistError
+                          , GPGError
+                          , MergeFileTreeError
+                          , NextVerNotFound
+                          , NoDownload
+                          , NoToolVersionSet
+                          , NotInstalled
+                          , ProcessError
+                          , TagNotFound
+                          , TarDirDoesNotExist
+                          , UninstallFailed
+                          , UnknownArchive
+                          , InstallSetError
                           ]
 
 runInstGHC :: AppState
@@ -393,23 +333,25 @@
     (case instBindist of
        Nothing -> runInstGHC s' instPlatform $ do
          (v, vi) <- liftE $ fromVersion instVer GHC
-         void $ liftE $ sequenceE (installGHCBin
+         liftE $ runBothE' (installGHCBin
                      (_tvVersion v)
                      (maybe GHCupInternal IsolateDir isolateDir)
                      forceInstall
+                     addConfArgs
                    )
-                   $ when instSet $ when (isNothing isolateDir) $ void $ setGHC v SetGHCOnly Nothing
+                   $ when instSet $ when (isNothing isolateDir) $ liftE $ void $ setGHC v SetGHCOnly Nothing
          pure vi
        Just uri -> do
          runInstGHC s'{ settings = settings {noVerify = True}} instPlatform $ do
            (v, vi) <- liftE $ fromVersion instVer GHC
-           void $ liftE $ sequenceE (installGHCBindist
+           liftE $ runBothE' (installGHCBindist
                        (DownloadInfo uri (Just $ RegexDir "ghc-.*") "")
                        (_tvVersion v)
                        (maybe GHCupInternal IsolateDir isolateDir)
                        forceInstall
+                       addConfArgs
                      )
-                     $ when instSet $ when (isNothing isolateDir) $ void $ setGHC v SetGHCOnly Nothing
+                     $ when instSet $ when (isNothing isolateDir) $ liftE $ void $ setGHC v SetGHCOnly Nothing
            pure vi
       )
         >>= \case
@@ -419,20 +361,18 @@
                   runLogger $ logInfo msg
                 pure ExitSuccess
 
-              VLeft (V (AlreadyInstalled _ v, ())) -> do
-                runLogger $ logWarn $
-                  "GHC ver " <> prettyVer v <> " already installed, remove it first to reinstall"
+              VLeft e@(V (AlreadyInstalled _ _)) -> do
+                runLogger $ logWarn $ T.pack $ prettyShow e
                 pure ExitSuccess
-              VLeft (V (AlreadyInstalled _ v)) -> do
-                runLogger $ logWarn $
-                  "GHC ver " <> prettyVer v <> " already installed, remove it first to reinstall"
+              VLeft e@(V (AlreadyInstalled _ _)) -> do
+                runLogger $ logWarn $ T.pack $ prettyShow e
                 pure ExitSuccess
 
               VLeft (V (DirNotEmpty fp)) -> do
                 runLogger $ logError $
                   "Install directory " <> T.pack fp <> " is not empty."
                 pure $ ExitFailure 3
-              VLeft (V (DirNotEmpty fp, ())) -> do
+              VLeft (V (DirNotEmpty fp)) -> do
                 runLogger $ logError $
                   "Install directory " <> T.pack fp <> " is not empty."
                 pure $ ExitFailure 3
@@ -441,21 +381,21 @@
                 case keepDirs settings of
                   Never -> runLogger (logError $ T.pack $ prettyShow err)
                   _ -> runLogger (logError $ T.pack (prettyShow err) <> "\n" <>
-                    "Check the logs at " <> T.pack logsDir <> " and the build directory " <> T.pack tmpdir <> " for more clues." <> "\n" <>
+                    "Check the logs at " <> T.pack (fromGHCupPath logsDir) <> " and the build directory " <> T.pack tmpdir <> " for more clues." <> "\n" <>
                     "Make sure to clean up " <> T.pack tmpdir <> " afterwards.")
                 pure $ ExitFailure 3
-              VLeft err@(V (BuildFailed tmpdir _, ())) -> do
+              VLeft err@(V (BuildFailed tmpdir _)) -> do
                 case keepDirs settings of
                   Never -> runLogger (logError $ T.pack $ prettyShow err)
                   _ -> runLogger (logError $ T.pack (prettyShow err) <> "\n" <>
-                    "Check the logs at " <> T.pack logsDir <> " and the build directory " <> T.pack tmpdir <> " for more clues." <> "\n" <>
+                    "Check the logs at " <> T.pack (fromGHCupPath logsDir) <> " and the build directory " <> T.pack tmpdir <> " for more clues." <> "\n" <>
                     "Make sure to clean up " <> T.pack tmpdir <> " afterwards.")
                 pure $ ExitFailure 3
 
               VLeft e -> do
                 runLogger $ do
                   logError $ T.pack $ prettyShow e
-                  logError $ "Also check the logs in " <> T.pack logsDir
+                  logError $ "Also check the logs in " <> T.pack (fromGHCupPath logsDir)
                 pure $ ExitFailure 3
 
 
@@ -465,21 +405,21 @@
     (case instBindist of
        Nothing -> runInstTool s' instPlatform $ do
          (_tvVersion -> v, vi) <- liftE $ fromVersion instVer Cabal
-         void $ liftE $ sequenceE (installCabalBin
+         liftE $ runBothE' (installCabalBin
                                     v
                                     (maybe GHCupInternal IsolateDir isolateDir)
                                     forceInstall
-                                  ) $ when instSet $ when (isNothing isolateDir) $ void $ setCabal v
+                                  ) $ when instSet $ when (isNothing isolateDir) $ liftE $ setCabal v
          pure vi
        Just uri -> do
          runInstTool s'{ settings = settings { noVerify = True}} instPlatform $ do
            (_tvVersion -> v, vi) <- liftE $ fromVersion instVer Cabal
-           void $ liftE $ sequenceE (installCabalBindist
+           liftE $ runBothE' (installCabalBindist
                                       (DownloadInfo uri Nothing "")
                                       v
                                       (maybe GHCupInternal IsolateDir isolateDir)
                                       forceInstall
-                                    ) $ when instSet $ when (isNothing isolateDir) $ void $ setCabal v
+                                    ) $ when instSet $ when (isNothing isolateDir) $ liftE $ setCabal v
            pure vi
       )
       >>= \case
@@ -488,26 +428,24 @@
               forM_ (_viPostInstall =<< vi) $ \msg ->
                 runLogger $ logInfo msg
               pure ExitSuccess
-            VLeft (V (AlreadyInstalled _ v)) -> do
-              runLogger $ logWarn $
-                "Cabal ver " <> prettyVer v <> " already installed; if you really want to reinstall it, you may want to run 'ghcup install cabal --force " <> prettyVer v <> "'"
+            VLeft e@(V (AlreadyInstalled _ _)) -> do
+              runLogger $ logWarn $ T.pack $ prettyShow e
               pure ExitSuccess
             VLeft (V (FileAlreadyExistsError fp)) -> do
               runLogger $ logWarn $
                 "File " <> T.pack fp <> " already exists. Use 'ghcup install cabal --isolate " <> T.pack fp <> " --force ..." <> "' if you want to overwrite."
               pure $ ExitFailure 3
-            VLeft (V (AlreadyInstalled _ v, ())) -> do
-              runLogger $ logWarn $
-                "Cabal ver " <> prettyVer v <> " already installed; if you really want to reinstall it, you may want to run 'ghcup install cabal --force " <> prettyVer v <> "'"
+            VLeft e@(V (AlreadyInstalled _ _)) -> do
+              runLogger $ logWarn $ T.pack $ prettyShow e
               pure ExitSuccess
-            VLeft (V (FileAlreadyExistsError fp, ())) -> do
+            VLeft (V (FileAlreadyExistsError fp)) -> do
               runLogger $ logWarn $
                 "File " <> T.pack fp <> " already exists. Use 'ghcup install cabal --isolate " <> T.pack fp <> " --force ..." <> "' if you want to overwrite."
               pure $ ExitFailure 3
             VLeft e -> do
               runLogger $ do
                 logError $ T.pack $ prettyShow e
-                logError $ "Also check the logs in " <> T.pack logsDir
+                logError $ "Also check the logs in " <> T.pack (fromGHCupPath logsDir)
               pure $ ExitFailure 4
 
   installHLS :: InstallOptions -> IO ExitCode
@@ -516,22 +454,22 @@
      (case instBindist of
        Nothing -> runInstTool s' instPlatform $ do
          (_tvVersion -> v, vi) <- liftE $ fromVersion instVer HLS
-         void $ liftE $ sequenceE (installHLSBin
+         liftE $ runBothE' (installHLSBin
                                     v
                                     (maybe GHCupInternal IsolateDir isolateDir)
                                     forceInstall
-                                  ) $ when instSet $ when (isNothing isolateDir) $ void $ setHLS v SetHLSOnly Nothing
+                                  ) $ when instSet $ when (isNothing isolateDir) $ liftE $ setHLS v SetHLSOnly Nothing
          pure vi
        Just uri -> do
          runInstTool s'{ settings = settings { noVerify = True}} instPlatform $ do
            (_tvVersion -> v, vi) <- liftE $ fromVersion instVer HLS
            -- TODO: support legacy
-           void $ liftE $ sequenceE (installHLSBindist
+           liftE $ runBothE' (installHLSBindist
                                       (DownloadInfo uri (Just $ RegexDir "haskell-language-server-*") "")
                                       v
                                       (maybe GHCupInternal IsolateDir isolateDir)
                                       forceInstall
-                                    ) $ when instSet $ when (isNothing isolateDir) $ void $ setHLS v SetHLSOnly Nothing
+                                    ) $ when instSet $ when (isNothing isolateDir) $ liftE $ setHLS v SetHLSOnly Nothing
            pure vi
       )
       >>= \case
@@ -540,34 +478,24 @@
               forM_ (_viPostInstall =<< vi) $ \msg ->
                 runLogger $ logInfo msg
               pure ExitSuccess
-            VLeft (V (AlreadyInstalled _ v)) -> do
-              runLogger $ logWarn $
-                  "HLS ver "
-                <> prettyVer v
-                <> " already installed; if you really want to reinstall it, you may want to run 'ghcup install hls --force "
-                <> prettyVer v
-                <> "'"
+            VLeft e@(V (AlreadyInstalled _ _)) -> do
+              runLogger $ logWarn $ T.pack $ prettyShow e
               pure ExitSuccess
             VLeft (V (FileAlreadyExistsError fp)) -> do
               runLogger $ logWarn $
                 "File " <> T.pack fp <> " already exists. Use 'ghcup install hls --isolate " <> T.pack fp <> " --force ..." <> "' if you want to overwrite."
               pure $ ExitFailure 3
-            VLeft (V (AlreadyInstalled _ v, ())) -> do
-              runLogger $ logWarn $
-                  "HLS ver "
-                <> prettyVer v
-                <> " already installed; if you really want to reinstall it, you may want to run 'ghcup install hls --force "
-                <> prettyVer v
-                <> "'"
+            VLeft e@(V (AlreadyInstalled _ _)) -> do
+              runLogger $ logWarn $ T.pack $ prettyShow e
               pure ExitSuccess
-            VLeft (V (FileAlreadyExistsError fp, ())) -> do
+            VLeft (V (FileAlreadyExistsError fp)) -> do
               runLogger $ logWarn $
                 "File " <> T.pack fp <> " already exists. Use 'ghcup install hls --isolate " <> T.pack fp <> " --force ..." <> "' if you want to overwrite."
               pure $ ExitFailure 3
             VLeft e -> do
               runLogger $ do
                 logError $ T.pack $ prettyShow e
-                logError $ "Also check the logs in " <> T.pack logsDir
+                logError $ "Also check the logs in " <> T.pack (fromGHCupPath logsDir)
               pure $ ExitFailure 4
 
   installStack :: InstallOptions -> IO ExitCode
@@ -576,21 +504,21 @@
      (case instBindist of
         Nothing -> runInstTool s' instPlatform $ do
           (_tvVersion -> v, vi) <- liftE $ fromVersion instVer Stack
-          void $ liftE $ sequenceE (installStackBin
+          liftE $ runBothE' (installStackBin
                                      v
                                      (maybe GHCupInternal IsolateDir isolateDir)
                                      forceInstall
-                                   ) $ when instSet $ when (isNothing isolateDir) $ void $ setStack v
+                                   ) $ when instSet $ when (isNothing isolateDir) $ liftE $ setStack v
           pure vi
         Just uri -> do
           runInstTool s'{ settings = settings { noVerify = True}} instPlatform $ do
             (_tvVersion -> v, vi) <- liftE $ fromVersion instVer Stack
-            void $ liftE $ sequenceE (installStackBindist
+            liftE $ runBothE' (installStackBindist
                                        (DownloadInfo uri Nothing "")
                                        v
                                        (maybe GHCupInternal IsolateDir isolateDir)
                                        forceInstall
-                                     ) $ when instSet $ when (isNothing isolateDir) $ void $ setStack v
+                                     ) $ when instSet $ when (isNothing isolateDir) $ liftE $ setStack v
             pure vi
       )
       >>= \case
@@ -599,25 +527,23 @@
               forM_ (_viPostInstall =<< vi) $ \msg ->
                 runLogger $ logInfo msg
               pure ExitSuccess
-            VLeft (V (AlreadyInstalled _ v)) -> do
-              runLogger $ logWarn $
-                "Stack ver " <> prettyVer v <> " already installed; if you really want to reinstall it, you may want to run 'ghcup install stack --force " <> prettyVer v <> "'"
+            VLeft e@(V (AlreadyInstalled _ _)) -> do
+              runLogger $ logWarn $ T.pack $ prettyShow e
               pure ExitSuccess
             VLeft (V (FileAlreadyExistsError fp)) -> do
               runLogger $ logWarn $
                 "File " <> T.pack fp <> " already exists. Use 'ghcup install stack --isolate " <> T.pack fp <> " --force ..." <> "' if you want to overwrite."
               pure $ ExitFailure 3
-            VLeft (V (AlreadyInstalled _ v, ())) -> do
-              runLogger $ logWarn $
-                "Stack ver " <> prettyVer v <> " already installed; if you really want to reinstall it, you may want to run 'ghcup install stack --force " <> prettyVer v <> "'"
+            VLeft e@(V (AlreadyInstalled _ _)) -> do
+              runLogger $ logWarn $ T.pack $ prettyShow e
               pure ExitSuccess
-            VLeft (V (FileAlreadyExistsError fp, ())) -> do
+            VLeft (V (FileAlreadyExistsError fp)) -> do
               runLogger $ logWarn $
                 "File " <> T.pack fp <> " already exists. Use 'ghcup install stack --isolate " <> T.pack fp <> " --force ..." <> "' if you want to overwrite."
               pure $ ExitFailure 3
             VLeft e -> do
               runLogger $ do
                 logError $ T.pack $ prettyShow e
-                logError $ "Also check the logs in " <> T.pack logsDir
+                logError $ "Also check the logs in " <> T.pack (fromGHCupPath logsDir)
               pure $ ExitFailure 4
 
diff --git a/app/ghcup/GHCup/OptParse/List.hs b/app/ghcup/GHCup/OptParse/List.hs
--- a/app/ghcup/GHCup/OptParse/List.hs
+++ b/app/ghcup/GHCup/OptParse/List.hs
@@ -11,7 +11,7 @@
 
 
 import           GHCup
-import           GHCup.Utils.Prelude
+import           GHCup.Prelude
 import           GHCup.Types
 import           GHCup.OptParse.Common
 
diff --git a/app/ghcup/GHCup/OptParse/Nuke.hs b/app/ghcup/GHCup/OptParse/Nuke.hs
--- a/app/ghcup/GHCup/OptParse/Nuke.hs
+++ b/app/ghcup/GHCup/OptParse/Nuke.hs
@@ -14,7 +14,7 @@
 import           GHCup
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Utils.Logger
+import           GHCup.Prelude.Logger
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -42,7 +42,7 @@
     ---------------------------
 
 
-type NukeEffects = '[ NotInstalled ]
+type NukeEffects = '[ NotInstalled, UninstallFailed ]
 
 
 runNuke :: AppState
diff --git a/app/ghcup/GHCup/OptParse/Prefetch.hs b/app/ghcup/GHCup/OptParse/Prefetch.hs
--- a/app/ghcup/GHCup/OptParse/Prefetch.hs
+++ b/app/ghcup/GHCup/OptParse/Prefetch.hs
@@ -14,9 +14,10 @@
 import           GHCup
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Utils.Logger
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 import           GHCup.OptParse.Common
-import           GHCup.Utils.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -33,7 +34,6 @@
 
 import qualified Data.Text                     as T
 import Control.Exception.Safe (MonadMask)
-import GHCup.Utils.Prelude
 import GHCup.Download (getDownloadsF)
 
 
@@ -74,44 +74,44 @@
     --[ Parsers ]--
     ---------------
 
-          
+
 prefetchP :: Parser PrefetchCommand
 prefetchP = subparser
   (  command
       "ghc"
-      (info 
+      (info
         (PrefetchGHC
           <$> (PrefetchGHCOptions
                 <$> ( switch (short 's' <> long "source" <> help "Download source tarball instead of bindist") <**> helper )
                 <*> optional (option str (short 'd' <> long "directory" <> help "directory to download into (default: ~/.ghcup/cache/)" <> completer (bashCompleter "directory"))))
-          <*>  optional (toolVersionArgument Nothing (Just GHC)) )
+          <*>  optional (toolVersionTagArgument Nothing (Just GHC)) )
         ( progDesc "Download GHC assets for installation")
       )
       <>
      command
       "cabal"
-      (info 
+      (info
         (PrefetchCabal
           <$> fmap PrefetchOptions (optional (option str (short 'd' <> long "directory" <> help "directory to download into (default: ~/.ghcup/cache/)" <> completer (bashCompleter "directory"))))
-          <*> ( optional (toolVersionArgument Nothing (Just Cabal)) <**> helper ))
+          <*> ( optional (toolVersionTagArgument Nothing (Just Cabal)) <**> helper ))
         ( progDesc "Download cabal assets for installation")
       )
       <>
      command
       "hls"
-      (info 
+      (info
         (PrefetchHLS
           <$> fmap PrefetchOptions (optional (option str (short 'd' <> long "directory" <> help "directory to download into (default: ~/.ghcup/cache/)" <> completer (bashCompleter "directory"))))
-          <*> ( optional (toolVersionArgument Nothing (Just HLS)) <**> helper ))
+          <*> ( optional (toolVersionTagArgument Nothing (Just HLS)) <**> helper ))
         ( progDesc "Download HLS assets for installation")
       )
       <>
      command
       "stack"
-      (info 
+      (info
         (PrefetchStack
           <$> fmap PrefetchOptions (optional (option str (short 'd' <> long "directory" <> help "directory to download into (default: ~/.ghcup/cache/)" <> completer (bashCompleter "directory"))))
-          <*> ( optional (toolVersionArgument Nothing (Just Stack)) <**> helper ))
+          <*> ( optional (toolVersionTagArgument Nothing (Just Stack)) <**> helper ))
         ( progDesc "Download stack assets for installation")
       )
       <>
diff --git a/app/ghcup/GHCup/OptParse/Rm.hs b/app/ghcup/GHCup/OptParse/Rm.hs
--- a/app/ghcup/GHCup/OptParse/Rm.hs
+++ b/app/ghcup/GHCup/OptParse/Rm.hs
@@ -18,9 +18,9 @@
 import           GHCup.Types
 import           GHCup.Types.Optics
 import           GHCup.Utils
-import           GHCup.Utils.Logger
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 import           GHCup.OptParse.Common
-import           GHCup.Utils.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -71,7 +71,7 @@
     --[ Parsers ]--
     ---------------
 
-          
+
 rmParser :: Parser (Either RmCommand RmOptions)
 rmParser =
   (Left <$> subparser
@@ -103,7 +103,7 @@
 
 
 rmOpts :: Maybe Tool -> Parser RmOptions
-rmOpts tool = RmOptions <$> versionArgument (Just ListInstalled) tool
+rmOpts tool = RmOptions <$> ghcVersionArgument (Just ListInstalled) tool
 
 
 
@@ -127,7 +127,7 @@
     ---------------------------
 
 
-type RmEffects = '[ NotInstalled ]
+type RmEffects = '[ NotInstalled, UninstallFailed ]
 
 
 runRm :: (ReaderT env m (VEither RmEffects a) -> m (VEither RmEffects a))
diff --git a/app/ghcup/GHCup/OptParse/Run.hs b/app/ghcup/GHCup/OptParse/Run.hs
--- a/app/ghcup/GHCup/OptParse/Run.hs
+++ b/app/ghcup/GHCup/OptParse/Run.hs
@@ -5,19 +5,24 @@
 {-# LANGUAGE RankNTypes        #-}
 {-# LANGUAGE FlexibleContexts  #-}
 {-# LANGUAGE TypeFamilies      #-}
+{-# LANGUAGE ViewPatterns      #-}
 module GHCup.OptParse.Run where
 
 
 import           GHCup
 import           GHCup.Utils
-import           GHCup.Utils.Prelude
-import           GHCup.Utils.File
 import           GHCup.OptParse.Common
 import           GHCup.Errors
 import           GHCup.Types
 import           GHCup.Types.Optics
-import           GHCup.Utils.Logger
-import           GHCup.Utils.String.QQ
+import           GHCup.Prelude
+import           GHCup.Prelude.File
+#ifdef IS_WINDOWS
+import           GHCup.Prelude.Process
+import           GHCup.Prelude.Process.Windows ( execNoMinGW )
+#endif
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 
 import           Control.Exception.Safe         ( MonadMask, MonadCatch )
 #if !MIN_VERSION_base(4,13,0)
@@ -32,7 +37,6 @@
 import           Haskus.Utils.Variant.Excepts
 import           Options.Applicative     hiding ( style )
 import           Prelude                 hiding ( appendFile )
-import           System.Directory
 import           System.FilePath
 import           System.Environment
 import           System.Exit
@@ -43,6 +47,7 @@
 #ifndef IS_WINDOWS
 import qualified System.Posix.Process          as SPP
 #endif
+import Data.Versions ( prettyVer, Version )
 
 
 
@@ -56,6 +61,7 @@
 data RunOptions = RunOptions
   { runAppendPATH :: Bool
   , runInstTool'  :: Bool
+  , runMinGWPath  :: Bool
   , runGHCVer     :: Maybe ToolVersion
   , runCabalVer   :: Maybe ToolVersion
   , runHLSVer     :: Maybe ToolVersion
@@ -80,9 +86,11 @@
           (short 'a' <> long "append" <> help "Append bin/ dir to PATH instead of prepending (this means that e.g. a system installation may take precedence)")
     <*> switch
           (short 'i' <> long "install" <> help "Install the tool, if missing")
+    <*> switch
+          (short 'm' <> long "mingw-path" <> help "On windows, add mingw64 PATHs to environment (does nothing on unix)")
     <*> optional
           (option
-            (eitherReader toolVersionEither)
+            (eitherReader ghcVersionTagEither)
             (metavar "GHC_VERSION" <> long "ghc" <> help "The ghc version"
             <> completer (tagCompleter GHC [])
             <> (completer $ versionCompleter Nothing GHC)
@@ -90,7 +98,7 @@
           )
     <*> optional
           (option
-            (eitherReader toolVersionEither)
+            (eitherReader toolVersionTagEither)
             (metavar "CABAL_VERSION" <> long "cabal" <> help "The cabal version"
             <> completer (tagCompleter Cabal [])
             <> (completer $ versionCompleter Nothing Cabal)
@@ -98,7 +106,7 @@
           )
     <*> optional
           (option
-            (eitherReader toolVersionEither)
+            (eitherReader toolVersionTagEither)
             (metavar "HLS_VERSION" <> long "hls" <> help "The HLS version"
             <> completer (tagCompleter HLS [])
             <> (completer $ versionCompleter Nothing HLS)
@@ -106,7 +114,7 @@
           )
     <*> optional
           (option
-            (eitherReader toolVersionEither)
+            (eitherReader toolVersionTagEither)
             (metavar "STACK_VERSION" <> long "stack" <> help "The stack version"
             <> completer (tagCompleter Stack [])
             <> (completer $ versionCompleter Nothing Stack)
@@ -176,6 +184,8 @@
                    , NoToolVersionSet
                    , FileAlreadyExistsError
                    , ProcessError
+                   , UninstallFailed
+                   , MergeFileTreeError
                    ]
 
 runLeanRUN :: (MonadUnliftIO m, MonadIO m)
@@ -209,7 +219,7 @@
 
 
 
-run :: forall m. 
+run :: forall m .
        ( MonadFail m
        , MonadMask m
        , MonadCatch m
@@ -225,12 +235,16 @@
    r <- if not runQuick
         then runRUN runAppState $ do
          toolchain <- liftE resolveToolchainFull
-         tmp <- liftIO $ createTmpDir toolchain
+
+         -- oh dear
+         r <- lift ask
+         tmp <- lift . lift . lift . flip runReaderT (fromAppState r) $ createTmpDir toolchain
+
          liftE $ installToolChainFull toolchain tmp
          pure tmp
         else runLeanRUN leanAppstate $ do
          toolchain <- resolveToolchain
-         tmp <- liftIO $ createTmpDir toolchain
+         tmp <- lift $ createTmpDir toolchain
          liftE $ installToolChain toolchain tmp
          pure tmp
    case r of
@@ -245,7 +259,9 @@
                void $ liftIO $ SPP.executeFile cmd True args (Just newEnv)
                pure ExitSuccess
 #else
-               r' <- runLeanRUN leanAppstate $ liftE $ lEM @_ @'[ProcessError] $ exec cmd args Nothing (Just newEnv)
+               r' <- if runMinGWPath
+                     then runLeanRUN leanAppstate $ liftE $ lEM @_ @'[ProcessError] $ exec cmd args Nothing (Just newEnv)
+                     else runLeanRUN leanAppstate $ liftE $ lEM @_ @'[ProcessError] $ execNoMinGW cmd args Nothing (Just newEnv)
                case r' of
                  VRight _ -> pure ExitSuccess
                  VLeft e -> do
@@ -258,17 +274,6 @@
 
   where
 
-   createTmpDir :: Toolchain -> IO FilePath
-   createTmpDir toolchain =
-     case runBinDir of
-           Just bindir -> do
-             createDirRecursive' bindir
-             canonicalizePath bindir
-           Nothing -> do
-             d <- predictableTmpDir toolchain
-             createDirRecursive' d
-             canonicalizePath d
-
    -- TODO: doesn't work for cross
    resolveToolchainFull :: ( MonadFail m
                            , MonadThrow m
@@ -286,29 +291,33 @@
            pure v
          cabalVer <- forM runCabalVer $ \ver -> do
            (v, _) <- liftE $ fromVersion (Just ver) Cabal
-           pure v
+           pure (_tvVersion v)
          hlsVer <- forM runHLSVer $ \ver -> do
            (v, _) <- liftE $ fromVersion (Just ver) HLS
-           pure v
+           pure (_tvVersion v)
          stackVer <- forM runStackVer $ \ver -> do
            (v, _) <- liftE $ fromVersion (Just ver) Stack
-           pure v
+           pure (_tvVersion v)
          pure Toolchain{..}
 
    resolveToolchain = do
          ghcVer <- case runGHCVer of
-            Just (ToolVersion v) -> pure $ Just v
+            Just (GHCVersion v) -> pure $ Just v
+            Just (ToolVersion v) -> pure $ Just (mkTVer v)
             Nothing -> pure Nothing
             _ -> fail "Internal error"
          cabalVer <- case runCabalVer of
+            Just (GHCVersion v) -> pure $ Just (_tvVersion v)
             Just (ToolVersion v) -> pure $ Just v
             Nothing -> pure Nothing
             _ -> fail "Internal error"
          hlsVer <- case runHLSVer of
+            Just (GHCVersion v) -> pure $ Just (_tvVersion v)
             Just (ToolVersion v) -> pure $ Just v
             Nothing -> pure Nothing
             _ -> fail "Internal error"
          stackVer <- case runStackVer of
+            Just (GHCVersion v) -> pure $ Just (_tvVersion v)
             Just (ToolVersion v) -> pure $ Just v
             Nothing -> pure Nothing
             _ -> fail "Internal error"
@@ -339,36 +348,47 @@
                               , AlreadyInstalled
                               , FileAlreadyExistsError
                               , CopyError
+                              , UninstallFailed
+                              , MergeFileTreeError
                               ] (ResourceT (ReaderT AppState m)) ()
    installToolChainFull Toolchain{..} tmp = do
-         forM_ [(GHC,) <$> ghcVer, (Cabal,) <$> cabalVer, (HLS,) <$> hlsVer, (Stack,) <$> stackVer] $ \mt -> do
-           isInstalled <- maybe (pure False) (\(tool, v) -> lift $ checkIfToolInstalled' tool v) mt
-           case mt of
-             Just (GHC, v) -> do
-               unless isInstalled $ when (runInstTool' && isNothing (_tvTarget v)) $ void $ liftE $ installGHCBin
-                 (_tvVersion v)
-                 GHCupInternal
-                 False
-               setTool GHC v tmp
-             Just (Cabal, v) -> do
-               unless isInstalled $ when runInstTool' $ void $ liftE $ installCabalBin
-                 (_tvVersion v)
-                 GHCupInternal
-                 False
-               setTool Cabal v tmp
-             Just (Stack, v) -> do
-               unless isInstalled $ when runInstTool' $ void $ liftE $ installStackBin
-                 (_tvVersion v)
-                 GHCupInternal
-                 False
-               setTool Stack v tmp
-             Just (HLS, v) -> do
-               unless isInstalled $ when runInstTool' $ void $ liftE $ installHLSBin
-                 (_tvVersion v)
-                 GHCupInternal
-                 False
-               setTool HLS v tmp
-             _ -> pure ()
+         case ghcVer of
+           Just v -> do
+             isInstalled <- lift $ checkIfToolInstalled' GHC v
+             unless isInstalled $ when (runInstTool' && isNothing (_tvTarget v)) $ void $ liftE $ installGHCBin
+               (_tvVersion v)
+               GHCupInternal
+               False
+               []
+             setGHC' v tmp
+           _ -> pure ()
+         case cabalVer of
+           Just v -> do
+             isInstalled <- lift $ checkIfToolInstalled' Cabal (mkTVer v)
+             unless isInstalled $ when runInstTool' $ void $ liftE $ installCabalBin
+               v
+               GHCupInternal
+               False
+             setCabal' v tmp
+           _ -> pure ()
+         case stackVer of
+           Just v -> do
+             isInstalled <- lift $ checkIfToolInstalled' Stack (mkTVer v)
+             unless isInstalled $ when runInstTool' $ void $ liftE $ installStackBin
+               v
+               GHCupInternal
+               False
+             setStack' v tmp
+           _ -> pure ()
+         case hlsVer of
+           Just v -> do
+             isInstalled <- lift $ checkIfToolInstalled' HLS (mkTVer v)
+             unless isInstalled $ when runInstTool' $ void $ liftE $ installHLSBin
+               v
+               GHCupInternal
+               False
+             setHLS' v tmp
+           _ -> pure ()
 
    installToolChain :: ( MonadFail m
                        , MonadThrow m
@@ -379,46 +399,47 @@
                     -> FilePath
                     -> Excepts '[NotInstalled] (ReaderT LeanAppState m) ()
    installToolChain Toolchain{..} tmp = do
-         forM_ [(GHC,) <$> ghcVer, (Cabal,) <$> cabalVer, (HLS,) <$> hlsVer, (Stack,) <$> stackVer] $ \mt -> do
-           case mt of
-             Just (GHC, v)   -> setTool GHC v tmp
-             Just (Cabal, v) -> setTool Cabal v tmp
-             Just (Stack, v) -> setTool Stack v tmp
-             Just (HLS, v)   -> setTool HLS v tmp
-             _ -> pure ()
+         case ghcVer of
+           Just v -> setGHC' v tmp
+           _ -> pure ()
+         case cabalVer of
+           Just v -> setCabal' v tmp
+           _ -> pure ()
+         case stackVer of
+           Just v -> setStack' v tmp
+           _ -> pure ()
+         case hlsVer of
+           Just v -> setHLS' v tmp
+           _ -> pure ()
 
-   setTool tool v tmp =
-      case tool of
-        GHC -> do
+   setGHC' v tmp = do
           void $ liftE $ setGHC v SetGHC_XYZ (Just tmp)
           void $ liftE $ setGHC v SetGHCOnly (Just tmp)
-        Cabal -> do
-          bin  <- liftE $ whereIsTool Cabal v
+   setCabal' v tmp = do
+          bin  <- liftE $ whereIsTool Cabal (mkTVer v)
           cbin <- liftIO $ canonicalizePath bin
           lift $ createLink (relativeSymlink tmp cbin) (tmp </> ("cabal" <.> exeExt))
-        Stack -> do
-          bin  <- liftE $ whereIsTool Stack v
+   setStack' v tmp = do
+          bin  <- liftE $ whereIsTool Stack (mkTVer v)
           cbin <- liftIO $ canonicalizePath bin
           lift $ createLink (relativeSymlink tmp cbin) (tmp </> ("stack" <.> exeExt))
-        HLS -> do
+   setHLS' v tmp = do
           Dirs {..}  <- getDirs
-          let v' = _tvVersion v
-          legacy <- isLegacyHLS v'
+          legacy <- isLegacyHLS v
           if legacy
           then do
             -- TODO: factor this out
-            hlsWrapper <- liftE @_ @'[NotInstalled] $ hlsWrapperBinary v' !? (NotInstalled HLS (mkTVer v'))
+            hlsWrapper <- liftE @_ @'[NotInstalled] $ hlsWrapperBinary v !? (NotInstalled HLS (mkTVer v))
             cw <- liftIO $ canonicalizePath (binDir </> hlsWrapper)
             lift $ createLink (relativeSymlink tmp cw) (tmp </> takeFileName cw)
-            hlsBins <- hlsServerBinaries v' Nothing >>= liftIO . traverse (canonicalizePath . (binDir </>))
+            hlsBins <- hlsServerBinaries v Nothing >>= liftIO . traverse (canonicalizePath . (binDir </>))
             forM_ hlsBins $ \bin ->
               lift $ createLink (relativeSymlink tmp bin) (tmp </> takeFileName bin)
-            liftE $ setHLS (_tvVersion v) SetHLSOnly (Just tmp)
+            liftE $ setHLS v SetHLSOnly (Just tmp)
           else do
-            liftE $ setHLS (_tvVersion v) SetHLS_XYZ (Just tmp)
-            liftE $ setHLS (_tvVersion v) SetHLSOnly (Just tmp)
-        GHCup -> pure ()
-       
+            liftE $ setHLS v SetHLS_XYZ (Just tmp)
+            liftE $ setHLS v SetHLSOnly (Just tmp)
+
    addToPath path = do
     cEnv <- Map.fromList <$> getEnvironment
     let paths          = ["PATH", "Path"]
@@ -430,16 +451,38 @@
     liftIO $ setEnv pathVar newPath
     return envWithNewPath
 
-   predictableTmpDir (Toolchain Nothing Nothing Nothing Nothing) =
-     liftIO (getTemporaryDirectory >>= \tmp -> pure (tmp </> "ghcup-none"))
+   createTmpDir :: ( MonadUnliftIO m
+                   , MonadCatch m
+                   , MonadThrow m
+                   , MonadMask m
+                   , MonadIO m
+                   )
+                => Toolchain
+                -> ReaderT LeanAppState m FilePath
+   createTmpDir toolchain =
+     case runBinDir of
+           Just bindir -> do
+             liftIO $ createDirRecursive' bindir
+             liftIO $ canonicalizePath bindir
+           Nothing -> do
+             d <- predictableTmpDir toolchain
+             liftIO $ createDirRecursive' d
+             liftIO $ canonicalizePath d
+
+   predictableTmpDir :: Monad m
+                     => Toolchain
+                     -> ReaderT LeanAppState m FilePath
+   predictableTmpDir (Toolchain Nothing Nothing Nothing Nothing) = do
+     Dirs { tmpDir } <- getDirs
+     pure (fromGHCupPath tmpDir </> "ghcup-none")
    predictableTmpDir Toolchain{..} = do
-      tmp <- getTemporaryDirectory
-      pure $ tmp
+      Dirs { tmpDir } <- getDirs
+      pure $ fromGHCupPath tmpDir
         </> ("ghcup-" <> intercalate "_"
               (  maybe [] ( (:[]) . ("ghc-"   <>) . T.unpack . tVerToText) ghcVer
-              <> maybe [] ( (:[]) . ("cabal-" <>) . T.unpack . tVerToText) cabalVer
-              <> maybe [] ( (:[]) . ("hls-"   <>) . T.unpack . tVerToText) hlsVer
-              <> maybe [] ( (:[]) . ("stack-" <>) . T.unpack . tVerToText) stackVer
+              <> maybe [] ( (:[]) . ("cabal-" <>) . T.unpack . prettyVer) cabalVer
+              <> maybe [] ( (:[]) . ("hls-"   <>) . T.unpack . prettyVer) hlsVer
+              <> maybe [] ( (:[]) . ("stack-" <>) . T.unpack . prettyVer) stackVer
               )
             )
 
@@ -453,7 +496,7 @@
 
 data Toolchain = Toolchain
   { ghcVer     :: Maybe GHCTargetVersion
-  , cabalVer   :: Maybe GHCTargetVersion
-  , hlsVer     :: Maybe GHCTargetVersion
-  , stackVer   :: Maybe GHCTargetVersion
-  }
+  , cabalVer   :: Maybe Version
+  , hlsVer     :: Maybe Version
+  , stackVer   :: Maybe Version
+  } deriving Show
diff --git a/app/ghcup/GHCup/OptParse/Set.hs b/app/ghcup/GHCup/OptParse/Set.hs
--- a/app/ghcup/GHCup/OptParse/Set.hs
+++ b/app/ghcup/GHCup/OptParse/Set.hs
@@ -17,8 +17,8 @@
 import           GHCup
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Utils.Logger
-import           GHCup.Utils.String.QQ
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -74,7 +74,7 @@
     --[ Parsers ]--
     ---------------
 
-          
+
 setParser :: Parser (Either SetCommand SetOptions)
 setParser =
   (Left <$> subparser
@@ -82,7 +82,7 @@
           "ghc"
           (   SetGHC
           <$> info
-                (setOpts (Just GHC) <**> helper)
+                (setOpts GHC <**> helper)
                 (  progDesc "Set GHC version"
                 <> footerDoc (Just $ text setGHCFooter)
                 )
@@ -91,7 +91,7 @@
            "cabal"
            (   SetCabal
            <$> info
-                 (setOpts (Just Cabal) <**> helper)
+                 (setOpts Cabal <**> helper)
                  (  progDesc "Set Cabal version"
                  <> footerDoc (Just $ text setCabalFooter)
                  )
@@ -100,7 +100,7 @@
            "hls"
            (   SetHLS
            <$> info
-                 (setOpts (Just HLS) <**> helper)
+                 (setOpts HLS <**> helper)
                  (  progDesc "Set haskell-language-server version"
                  <> footerDoc (Just $ text setHLSFooter)
                  )
@@ -109,14 +109,14 @@
            "stack"
            (   SetStack
            <$> info
-                 (setOpts (Just Stack) <**> helper)
+                 (setOpts Stack <**> helper)
                  (  progDesc "Set stack version"
                  <> footerDoc (Just $ text setStackFooter)
                  )
            )
       )
     )
-    <|> (Right <$> setOpts Nothing)
+    <|> (Right <$> setOpts GHC)
  where
   setGHCFooter :: String
   setGHCFooter = [s|Discussion:
@@ -137,22 +137,25 @@
     Sets the the current haskell-language-server version.|]
 
 
-setOpts :: Maybe Tool -> Parser SetOptions
+setOpts :: Tool -> Parser SetOptions
 setOpts tool = SetOptions <$>
     (fromMaybe SetRecommended <$>
       optional (setVersionArgument (Just ListInstalled) tool))
 
-setVersionArgument :: Maybe ListCriteria -> Maybe Tool -> Parser SetToolVersion
+setVersionArgument :: Maybe ListCriteria -> Tool -> Parser SetToolVersion
 setVersionArgument criteria tool =
   argument (eitherReader setEither)
     (metavar "VERSION|TAG|next"
-    <> completer (tagCompleter (fromMaybe GHC tool) ["next"])
-    <> foldMap (completer . versionCompleter criteria) tool)
+    <> completer (tagCompleter tool ["next"])
+    <> (completer . versionCompleter criteria) tool)
  where
   setEither s' =
         parseSet s'
     <|> second SetToolTag (tagEither s')
-    <|> second SetToolVersion (tVersionEither s')
+    <|> se s'
+  se s' = case tool of
+           GHC -> second SetGHCVersion (ghcVersionEither s')
+           _   -> second SetToolVersion (toolVersionEither s')
   parseSet s' = case fmap toLower s' of
                   "next" -> Right SetNext
                   other  -> Left $ "Unknown tag/version " <> other
@@ -261,9 +264,9 @@
   (Right sopts) -> do
     runLogger (logWarn "This is an old-style command for setting GHC. Use 'ghcup set ghc' instead.")
     setGHC' sopts
-  (Left (SetGHC sopts)) -> setGHC' sopts
+  (Left (SetGHC sopts))   -> setGHC'   sopts
   (Left (SetCabal sopts)) -> setCabal' sopts
-  (Left (SetHLS sopts)) -> setHLS' sopts
+  (Left (SetHLS sopts))   -> setHLS'   sopts
   (Left (SetStack sopts)) -> setStack' sopts
 
  where
@@ -271,7 +274,7 @@
           -> m ExitCode
   setGHC' SetOptions{ sToolVer } =
     case sToolVer of
-      (SetToolVersion v) -> runSetGHC runLeanAppState (liftE $ setGHC v SetGHCOnly Nothing >> pure v)
+      (SetGHCVersion v) -> runSetGHC runLeanAppState (liftE $ setGHC v SetGHCOnly Nothing >> pure v)
       _ -> runSetGHC runAppState (do
           v <- liftE $ fst <$> fromVersion' sToolVer GHC
           liftE $ setGHC v SetGHCOnly Nothing
@@ -291,17 +294,17 @@
             -> m ExitCode
   setCabal' SetOptions{ sToolVer } =
     case sToolVer of
-      (SetToolVersion v) -> runSetCabal runLeanAppState (liftE $ setCabal (_tvVersion v) >> pure v)
+      (SetToolVersion v) -> runSetCabal runLeanAppState (liftE $ setCabal v >> pure (mkTVer v))
       _ -> runSetCabal runAppState (do
           v <- liftE $ fst <$> fromVersion' sToolVer Cabal
           liftE $ setCabal (_tvVersion v)
           pure v
         )
       >>= \case
-            VRight GHCTargetVersion{..} -> do
+            VRight v -> do
               runLogger
                 $ logInfo $
-                    "Cabal " <> prettyVer _tvVersion <> " successfully set as default version"
+                    "Cabal " <> prettyVer (_tvVersion v) <> " successfully set as default version"
               pure ExitSuccess
             VLeft  e -> do
               runLogger $ logError $ T.pack $ prettyShow e
@@ -311,17 +314,17 @@
           -> m ExitCode
   setHLS' SetOptions{ sToolVer } =
     case sToolVer of
-      (SetToolVersion v) -> runSetHLS runLeanAppState (liftE $ setHLS (_tvVersion v) SetHLSOnly Nothing >> pure v)
+      (SetToolVersion v) -> runSetHLS runLeanAppState (liftE $ setHLS v SetHLSOnly Nothing >> pure (mkTVer v))
       _ -> runSetHLS runAppState (do
           v <- liftE $ fst <$> fromVersion' sToolVer HLS
           liftE $ setHLS (_tvVersion v) SetHLSOnly Nothing
           pure v
         )
       >>= \case
-            VRight GHCTargetVersion{..} -> do
+            VRight v -> do
               runLogger
                 $ logInfo $
-                    "HLS " <> prettyVer _tvVersion <> " successfully set as default version"
+                    "HLS " <> prettyVer (_tvVersion v) <> " successfully set as default version"
               pure ExitSuccess
             VLeft  e -> do
               runLogger $ logError $ T.pack $ prettyShow e
@@ -332,17 +335,17 @@
             -> m ExitCode
   setStack' SetOptions{ sToolVer } =
     case sToolVer of
-      (SetToolVersion v) -> runSetStack runLeanAppState (liftE $ setStack (_tvVersion v) >> pure v)
+      (SetToolVersion v) -> runSetStack runLeanAppState (liftE $ setStack v >> pure (mkTVer v))
       _ -> runSetStack runAppState (do
             v <- liftE $ fst <$> fromVersion' sToolVer Stack
             liftE $ setStack (_tvVersion v)
             pure v
           )
       >>= \case
-            VRight GHCTargetVersion{..} -> do
+            VRight v -> do
               runLogger
                 $ logInfo $
-                    "Stack " <> prettyVer _tvVersion <> " successfully set as default version"
+                    "Stack " <> prettyVer (_tvVersion v) <> " successfully set as default version"
               pure ExitSuccess
             VLeft  e -> do
               runLogger $ logError $ T.pack $ prettyShow e
diff --git a/app/ghcup/GHCup/OptParse/ToolRequirements.hs b/app/ghcup/GHCup/OptParse/ToolRequirements.hs
--- a/app/ghcup/GHCup/OptParse/ToolRequirements.hs
+++ b/app/ghcup/GHCup/OptParse/ToolRequirements.hs
@@ -11,8 +11,8 @@
 
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Utils.Logger
-import           GHCup.Utils.String.QQ
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -30,7 +30,7 @@
 import Control.Exception.Safe (MonadMask)
 import GHCup.Types.Optics
 import GHCup.Platform
-import GHCup.Utils.Prelude
+import GHCup.Prelude
 import GHCup.Requirements
 import System.IO
 
diff --git a/app/ghcup/GHCup/OptParse/UnSet.hs b/app/ghcup/GHCup/OptParse/UnSet.hs
--- a/app/ghcup/GHCup/OptParse/UnSet.hs
+++ b/app/ghcup/GHCup/OptParse/UnSet.hs
@@ -16,8 +16,8 @@
 import           GHCup
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Utils.Logger
-import           GHCup.Utils.String.QQ
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
diff --git a/app/ghcup/GHCup/OptParse/Upgrade.hs b/app/ghcup/GHCup/OptParse/Upgrade.hs
--- a/app/ghcup/GHCup/OptParse/Upgrade.hs
+++ b/app/ghcup/GHCup/OptParse/Upgrade.hs
@@ -14,7 +14,8 @@
 import           GHCup
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Utils.Logger
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -93,7 +94,7 @@
                        , FileDoesNotExistError
                        , CopyError
                        , DownloadFailed
-                       , GHCupShadowed
+                       , ToolShadowed
                        ]
 
 
diff --git a/app/ghcup/GHCup/OptParse/Whereis.hs b/app/ghcup/GHCup/OptParse/Whereis.hs
--- a/app/ghcup/GHCup/OptParse/Whereis.hs
+++ b/app/ghcup/GHCup/OptParse/Whereis.hs
@@ -17,8 +17,9 @@
 import           GHCup.Errors
 import           GHCup.OptParse.Common
 import           GHCup.Types
-import           GHCup.Utils.Logger
-import           GHCup.Utils.String.QQ
+import           GHCup.Utils
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -74,14 +75,14 @@
     --[ Parsers ]--
     ---------------
 
-          
+
 whereisP :: Parser WhereisCommand
 whereisP = subparser
-  (commandGroup "Tools locations:" <> 
+  (commandGroup "Tools locations:" <>
     command
       "ghc"
       (WhereisTool GHC <$> info
-        ( optional (toolVersionArgument Nothing (Just GHC)) <**> helper )
+        ( optional (toolVersionTagArgument Nothing (Just GHC)) <**> helper )
         ( progDesc "Get GHC location"
         <> footerDoc (Just $ text whereisGHCFooter ))
       )
@@ -89,7 +90,7 @@
      command
       "cabal"
       (WhereisTool Cabal <$> info
-        ( optional (toolVersionArgument Nothing (Just Cabal)) <**> helper )
+        ( optional (toolVersionTagArgument Nothing (Just Cabal)) <**> helper )
         ( progDesc "Get cabal location"
         <> footerDoc (Just $ text whereisCabalFooter ))
       )
@@ -97,7 +98,7 @@
      command
       "hls"
       (WhereisTool HLS <$> info
-        ( optional (toolVersionArgument Nothing (Just HLS)) <**> helper )
+        ( optional (toolVersionTagArgument Nothing (Just HLS)) <**> helper )
         ( progDesc "Get HLS location"
         <> footerDoc (Just $ text whereisHLSFooter ))
       )
@@ -105,7 +106,7 @@
      command
       "stack"
       (WhereisTool Stack <$> info
-        ( optional (toolVersionArgument Nothing (Just Stack)) <**> helper )
+        ( optional (toolVersionTagArgument Nothing (Just Stack)) <**> helper )
         ( progDesc "Get stack location"
         <> footerDoc (Just $ text whereisStackFooter ))
       )
@@ -267,7 +268,7 @@
 whereis whereisCommand whereisOptions runAppState leanAppstate runLogger = do
   Dirs{ .. }  <- runReaderT getDirs leanAppstate
   case (whereisCommand, whereisOptions) of
-    (WhereisTool tool (Just (ToolVersion v)), WhereisOptions{..}) ->
+    (WhereisTool tool (Just (GHCVersion v)), WhereisOptions{..}) ->
       runLeanWhereIs leanAppstate (do
         loc <- liftE $ whereIsTool tool v
         if directory
@@ -281,6 +282,20 @@
               VLeft e -> do
                 runLogger $ logError $ T.pack $ prettyShow e
                 pure $ ExitFailure 30
+    (WhereisTool tool (Just (ToolVersion v)), WhereisOptions{..}) ->
+      runLeanWhereIs leanAppstate (do
+        loc <- liftE $ whereIsTool tool (mkTVer v)
+        if directory
+        then pure $ takeDirectory loc
+        else pure loc
+        )
+        >>= \case
+              VRight r -> do
+                liftIO $ putStr r
+                pure ExitSuccess
+              VLeft e -> do
+                runLogger $ logError $ T.pack $ prettyShow e
+                pure $ ExitFailure 30
 
     (WhereisTool tool whereVer, WhereisOptions{..}) -> do
       runWhereIs runAppState (do
@@ -299,7 +314,7 @@
                 pure $ ExitFailure 30
 
     (WhereisBaseDir, _) -> do
-      liftIO $ putStr baseDir
+      liftIO $ putStr $ fromGHCupPath baseDir
       pure ExitSuccess
 
     (WhereisBinDir, _) -> do
@@ -307,13 +322,13 @@
       pure ExitSuccess
 
     (WhereisCacheDir, _) -> do
-      liftIO $ putStr cacheDir
+      liftIO $ putStr $ fromGHCupPath cacheDir
       pure ExitSuccess
 
     (WhereisLogsDir, _) -> do
-      liftIO $ putStr logsDir
+      liftIO $ putStr $ fromGHCupPath logsDir
       pure ExitSuccess
 
     (WhereisConfDir, _) -> do
-      liftIO $ putStr confDir
+      liftIO $ putStr $ fromGHCupPath confDir
       pure ExitSuccess
diff --git a/app/ghcup/Main.hs b/app/ghcup/Main.hs
--- a/app/ghcup/Main.hs
+++ b/app/ghcup/Main.hs
@@ -14,6 +14,8 @@
 import           BrickMain                    ( brickMain )
 #endif
 
+import qualified GHCup.GHC as GHC
+import qualified GHCup.HLS as HLS
 import           GHCup.OptParse
 
 import           GHCup.Download
@@ -22,9 +24,9 @@
 import           GHCup.Types
 import           GHCup.Types.Optics      hiding ( toolRequirements )
 import           GHCup.Utils
-import           GHCup.Utils.Logger
-import           GHCup.Utils.Prelude
-import           GHCup.Utils.String.QQ
+import           GHCup.Prelude
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
 import           GHCup.Version
 
 import           Cabal.Plan ( findPlanJson, SearchPlanJson(..) )
@@ -155,7 +157,6 @@
   versions. It maintains a self-contained ~/.ghcup directory.
 
 ENV variables:
-  * TMPDIR: where ghcup does the work (unpacking, building, ...)
   * GHCUP_INSTALL_BASE_PREFIX: the base of ghcup (default: $HOME)
   * GHCUP_USE_XDG_DIRS: set to anything to use XDG style directories
 
@@ -220,7 +221,7 @@
                 let s' = AppState settings dirs keybindings ghcupInfo pfreq loggerConfig
 
                 race_ (liftIO $ runReaderT cleanupTrash s')
-                      (threadDelay 5000000 >> runLogger (logWarn $ "Killing cleanup thread (exceeded 5s timeout)... please remove leftover files in " <> T.pack recycleDir <> " manually"))
+                      (threadDelay 5000000 >> runLogger (logWarn $ "Killing cleanup thread (exceeded 5s timeout)... please remove leftover files in " <> T.pack (fromGHCupPath recycleDir) <> " manually"))
 
                 case optCommand of
                   Nuke -> pure ()
@@ -237,7 +238,7 @@
                     | Just False <- optVerbose -> pure ()
                     | otherwise -> lookupEnv "GHCUP_SKIP_UPDATE_CHECK" >>= \case
                          Nothing -> void . flip runReaderT s' . runE @'[TagNotFound, NextVerNotFound, NoToolVersionSet] $ do
-                           newTools <- lift checkForUpdates 
+                           newTools <- lift checkForUpdates
                            forM_ newTools $ \newTool@(t, l) -> do
                              -- https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/283
                              alreadyInstalling' <- alreadyInstalling optCommand newTool
@@ -278,8 +279,8 @@
               runAppState action' = do
                 s' <- liftIO appState
                 runReaderT action' s'
-                  
 
+
           -----------------
           -- Run command --
           -----------------
@@ -338,14 +339,16 @@
   alreadyInstalling (Install (Left (InstallHLS InstallOptions{..})))     (HLS, ver)   = cmp' HLS instVer ver
   alreadyInstalling (Install (Left (InstallStack InstallOptions{..})))   (Stack, ver) = cmp' Stack instVer ver
   alreadyInstalling (Compile (CompileGHC GHCCompileOptions{ ovewrwiteVer = Just over }))
-    (GHC, ver)   = cmp' GHC (Just $ ToolVersion (mkTVer over)) ver
-  alreadyInstalling (Compile (CompileGHC GHCCompileOptions{ targetGhc = Left tver }))
-    (GHC, ver)   = cmp' GHC (Just $ ToolVersion (mkTVer tver)) ver
-  alreadyInstalling (Compile (CompileHLS HLSCompileOptions{ ovewrwiteVer = Just over }))
-    (HLS, ver)   = cmp' HLS (Just $ ToolVersion (mkTVer over)) ver
-  alreadyInstalling (Compile (CompileHLS HLSCompileOptions{ targetHLS = Left tver }))
-    (HLS, ver)   = cmp' HLS (Just $ ToolVersion (mkTVer tver)) ver
-  alreadyInstalling (Upgrade _ _ _) (GHCup, _) = pure True
+    (GHC, ver)   = cmp' GHC (Just $ GHCVersion (mkTVer over)) ver
+  alreadyInstalling (Compile (CompileGHC GHCCompileOptions{ targetGhc = GHC.SourceDist tver }))
+    (GHC, ver)   = cmp' GHC (Just $ ToolVersion tver) ver
+  alreadyInstalling (Compile (CompileHLS HLSCompileOptions{ ovewrwiteVer = Right over }))
+    (HLS, ver)   = cmp' HLS (Just $ ToolVersion over) ver
+  alreadyInstalling (Compile (CompileHLS HLSCompileOptions{ targetHLS = HLS.SourceDist tver }))
+    (HLS, ver)   = cmp' HLS (Just $ ToolVersion tver) ver
+  alreadyInstalling (Compile (CompileHLS HLSCompileOptions{ targetHLS = HLS.HackageDist tver }))
+    (HLS, ver)   = cmp' HLS (Just $ ToolVersion tver) ver
+  alreadyInstalling (Upgrade {}) (GHCup, _) = pure True
   alreadyInstalling _ _ = pure False
 
   cmp' :: ( HasLog env
diff --git a/cbits/dirutils.c b/cbits/dirutils.c
new file mode 100644
--- /dev/null
+++ b/cbits/dirutils.c
@@ -0,0 +1,7 @@
+#include "dirutils.h"
+
+unsigned int
+    __posixdir_d_type(struct dirent* d)
+    {
+      return(d -> d_type);
+    }
diff --git a/ghcup.cabal b/ghcup.cabal
--- a/ghcup.cabal
+++ b/ghcup.cabal
@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               ghcup
-version:            0.1.17.10
+version:            0.1.18.0
 license:            LGPL-3.0-only
 license-file:       LICENSE
 copyright:          Julian Ospald 2020
@@ -44,31 +44,40 @@
   manual:      True
 
 flag no-exe
-  description: Don't build any executables 
+  description: Don't build any executables
   default:     False
   manual:      True
 
 library
   exposed-modules:
     GHCup
+    GHCup.Cabal
     GHCup.Download
     GHCup.Download.Utils
     GHCup.Errors
+    GHCup.GHC
+    GHCup.HLS
+    GHCup.List
     GHCup.Platform
+    GHCup.Prelude
+    GHCup.Prelude.File
+    GHCup.Prelude.File.Search
+    GHCup.Prelude.Internal
+    GHCup.Prelude.Logger
+    GHCup.Prelude.Logger.Internal
+    GHCup.Prelude.MegaParsec
+    GHCup.Prelude.Process
+    GHCup.Prelude.String.QQ
+    GHCup.Prelude.Version.QQ
+    GHCup.Prompts
     GHCup.Requirements
+    GHCup.Stack
     GHCup.Types
     GHCup.Types.JSON
     GHCup.Types.JSON.Utils
     GHCup.Types.Optics
     GHCup.Utils
     GHCup.Utils.Dirs
-    GHCup.Utils.File
-    GHCup.Utils.File.Common
-    GHCup.Utils.Logger
-    GHCup.Utils.MegaParsec
-    GHCup.Utils.Prelude
-    GHCup.Utils.String.QQ
-    GHCup.Utils.Version.QQ
     GHCup.Version
 
   hs-source-dirs:     lib
@@ -100,8 +109,8 @@
     , base                  >=4.12       && <5
     , base16-bytestring     >=0.1.1.6    && <1.1
     , binary                ^>=0.8.6.0
-    , bytestring            ^>=0.10
-    , Cabal                 ^>=3.6.2.0
+    , bytestring            >=0.10       && <0.12
+    , Cabal                 ^>=3.0.0.0 || ^>=3.2.0.0 || ^>=3.4.0.0 || ^>=3.6.0.0
     , case-insensitive      ^>=1.2.1.0
     , casing                ^>=0.1.4.1
     , containers            ^>=0.6
@@ -109,6 +118,7 @@
     , deepseq               ^>=1.4.4.0
     , directory             ^>=1.3.6.0
     , disk-free-space       ^>=0.1.0.1
+    , exceptions            ^>=0.10
     , filepath              ^>=1.4.2.1
     , haskus-utils-types    ^>=1.5
     , haskus-utils-variant  ^>=3.2.1
@@ -126,6 +136,7 @@
     , safe                  ^>=0.3.18
     , safe-exceptions       ^>=0.1
     , split                 ^>=0.2.3.4
+    , streamly              ^>=0.8.2
     , strict-base           ^>=0.4
     , template-haskell      >=2.7        && <2.18
     , temporary             ^>=1.3
@@ -153,9 +164,11 @@
   if os(windows)
     cpp-options:   -DIS_WINDOWS
     other-modules:
-      GHCup.Utils.File.Windows
-      GHCup.Utils.Prelude.Windows
-      GHCup.Utils.Windows
+      GHCup.Prelude.File.Windows
+      GHCup.Prelude.Windows
+    -- GHCup.OptParse.Run uses this
+    exposed-modules:
+      GHCup.Prelude.Process.Windows
 
     build-depends:
       , bzlib
@@ -164,10 +177,13 @@
 
   else
     other-modules:
-      GHCup.Utils.File.Posix
-      GHCup.Utils.Posix
-      GHCup.Utils.Prelude.Posix
+      GHCup.Prelude.File.Posix
+      GHCup.Prelude.File.Posix.Foreign
+      GHCup.Prelude.File.Posix.Traversals
+      GHCup.Prelude.Posix
+      GHCup.Prelude.Process.Posix
 
+    c-sources:     cbits/dirutils.c
     build-depends:
       , bz2              >=0.5.0.5 && <1.1
       , terminal-size    ^>=0.3.2.1
@@ -221,13 +237,14 @@
     , aeson-pretty          ^>=0.8.8
     , async                 ^>=2.2.3
     , base                  >=4.12     && <5
-    , bytestring            ^>=0.10
+    , bytestring            >=0.10       && <0.12
     , cabal-plan            ^>=0.7.2
     , containers            ^>=0.6
     , deepseq               ^>=1.4
     , directory             ^>=1.3.6.0
     , filepath              ^>=1.4.2.1
     , ghcup
+    , haskus-utils-types    ^>=1.5
     , haskus-utils-variant  ^>=3.2.1
     , libarchive            ^>=3.0.3.0
     , megaparsec            >=8.0.0    && <9.3
@@ -271,7 +288,6 @@
   if flag(no-exe)
     buildable: False
 
-
 test-suite ghcup-test
   type:               exitcode-stdio-1.0
   main-is:            Main.hs
@@ -280,6 +296,7 @@
   other-modules:
     GHCup.ArbitraryTypes
     GHCup.Types.JSONSpec
+    GHCup.Utils.FileSpec
     Spec
 
   default-language:   Haskell2010
@@ -297,14 +314,17 @@
 
   build-depends:
     , base                      >=4.12    && <5
-    , bytestring                ^>=0.10
+    , bytestring            >=0.10       && <0.12
     , containers                ^>=0.6
-    , generic-arbitrary         >=0.1.0   && <0.3
+    , directory                 ^>=1.3.6.0
+    , filepath                  ^>=1.4.2.1
+    , generic-arbitrary         >=0.1.0  && < 0.2.1 || >=0.2.2 && <0.3
     , ghcup
     , hspec                     >=2.7.10  && <2.10
     , hspec-golden-aeson        ^>=0.9
     , QuickCheck                ^>=2.14.1
     , quickcheck-arbitrary-adt  ^>=0.3.1.0
+    , streamly                  ^>=0.8.2
     , text                      ^>=1.2.4.0
     , uri-bytestring            ^>=0.3.2.2
     , versions                  >=4.0.1   && <5.1
diff --git a/lib/GHCup.hs b/lib/GHCup.hs
--- a/lib/GHCup.hs
+++ b/lib/GHCup.hs
@@ -6,2940 +6,603 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings     #-}
 {-# LANGUAGE QuasiQuotes           #-}
-{-# LANGUAGE TemplateHaskell       #-}
-
-{-|
-Module      : GHCup
-Description : GHCup installation functions
-Copyright   : (c) Julian Ospald, 2020
-License     : LGPL-3.0
-Maintainer  : hasufell@hasufell.de
-Stability   : experimental
-Portability : portable
-
-This module contains the main functions that correspond
-to the command line interface, like installation, listing versions
-and so on.
-
-These are the entry points.
--}
-module GHCup where
-
-
-import           GHCup.Download
-import           GHCup.Errors
-import           GHCup.Platform
-import           GHCup.Types
-import           GHCup.Types.JSON               ( )
-import           GHCup.Types.Optics
-import           GHCup.Utils
-import           GHCup.Utils.File
-import           GHCup.Utils.Logger
-import           GHCup.Utils.Prelude
-import           GHCup.Utils.String.QQ
-import           GHCup.Utils.Version.QQ
-import           GHCup.Version
-
-import           Codec.Archive                  ( ArchiveResult )
-import           Control.Applicative
-import           Control.DeepSeq                ( force )
-import           Control.Exception              ( evaluate )
-import           Control.Exception.Safe
-import           Control.Monad
-#if !MIN_VERSION_base(4,13,0)
-import           Control.Monad.Fail             ( MonadFail )
-#endif
-import           Control.Monad.Reader
-import           Control.Monad.Trans.Resource
-                                         hiding ( throwM )
-import           Control.Monad.IO.Unlift        ( MonadUnliftIO( withRunInIO ) )
-import           Data.ByteString                ( ByteString )
-import           Data.Either
-import           Data.List
-import           Data.Maybe
-import           Data.List.NonEmpty             ( NonEmpty((:|)) )
-import           Data.String                    ( fromString )
-import           Data.Text                      ( Text )
-import           Data.Time.Clock
-import           Data.Time.Format.ISO8601
-import           Data.Versions                hiding ( patch )
-import           Distribution.Types.Version   hiding ( Version )
-import           Distribution.Types.PackageId
-import           Distribution.Types.PackageDescription
-import           Distribution.Types.GenericPackageDescription
-import           Distribution.PackageDescription.Parsec
-import           GHC.IO.Exception
-import           Haskus.Utils.Variant.Excepts
-import           Language.Haskell.TH
-import           Language.Haskell.TH.Syntax     ( Quasi(qAddDependentFile) )
-import           Optics
-import           Prelude                 hiding ( abs
-                                                , writeFile
-                                                )
-import           Safe                    hiding ( at )
-import           System.Directory        hiding ( findFiles )
-import           System.Environment
-import           System.FilePath
-import           System.IO.Error
-import           System.IO.Temp
-import           Text.PrettyPrint.HughesPJClass ( prettyShow )
-import           Text.Regex.Posix
-import           URI.ByteString
-
-import qualified Crypto.Hash.SHA256            as SHA256
-import qualified Data.List.NonEmpty            as NE
-import qualified Data.ByteString.Base16        as B16
-import qualified Data.ByteString               as B
-import qualified Data.ByteString.Lazy          as BL
-import qualified Data.Map.Strict               as Map
-import qualified Data.Text                     as T
-import qualified Data.Text.IO                  as T
-import qualified Data.Text.Encoding            as E
-import qualified Text.Megaparsec               as MP
-import GHCup.Utils.MegaParsec
-import Control.Concurrent (threadDelay)
-
-
-    ---------------------
-    --[ Tool fetching ]--
-    ---------------------
-
-
-fetchToolBindist :: ( MonadFail m
-                    , MonadMask m
-                    , MonadCatch m
-                    , MonadReader env m
-                    , HasDirs env
-                    , HasSettings env
-                    , HasPlatformReq env
-                    , HasGHCupInfo env
-                    , HasLog env
-                    , MonadResource m
-                    , MonadIO m
-                    , MonadUnliftIO m
-                    )
-                 => Version
-                 -> Tool
-                 -> Maybe FilePath
-                 -> Excepts
-                      '[ DigestError
-                       , GPGError
-                       , DownloadFailed
-                       , NoDownload
-                       ]
-                      m
-                      FilePath
-fetchToolBindist v t mfp = do
-  dlinfo <- liftE $ getDownloadInfo t v
-  liftE $ downloadCached' dlinfo Nothing mfp
-
-
-fetchGHCSrc :: ( MonadFail m
-               , MonadMask m
-               , MonadCatch m
-               , MonadReader env m
-               , HasDirs env
-               , HasSettings env
-               , HasPlatformReq env
-               , HasGHCupInfo env
-               , HasLog env
-               , MonadResource m
-               , MonadIO m
-               , MonadUnliftIO m
-               )
-            => Version
-            -> Maybe FilePath
-            -> Excepts
-                 '[ DigestError
-                  , GPGError
-                  , DownloadFailed
-                  , NoDownload
-                  ]
-                 m
-                 FilePath
-fetchGHCSrc v mfp = do
-  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
-  dlInfo <-
-    preview (ix GHC % ix v % viSourceDL % _Just) dls
-      ?? NoDownload
-  liftE $ downloadCached' dlInfo Nothing mfp
-
-
-
-    -------------------------
-    --[ Tool installation ]--
-    -------------------------
-
-
--- | Like 'installGHCBin', except takes the 'DownloadInfo' as
--- argument instead of looking it up from 'GHCupDownloads'.
-installGHCBindist :: ( MonadFail m
-                     , MonadMask m
-                     , MonadCatch m
-                     , MonadReader env m
-                     , HasDirs env
-                     , HasSettings env
-                     , HasPlatformReq env
-                     , HasLog env
-                     , MonadResource m
-                     , MonadIO m
-                     , MonadUnliftIO m
-                     )
-                  => DownloadInfo    -- ^ where/how to download
-                  -> Version         -- ^ the version to install
-                  -> InstallDir
-                  -> Bool            -- ^ Force install
-                  -> Excepts
-                       '[ AlreadyInstalled
-                        , BuildFailed
-                        , DigestError
-                        , GPGError
-                        , DownloadFailed
-                        , NoDownload
-                        , NotInstalled
-                        , UnknownArchive
-                        , TarDirDoesNotExist
-                        , DirNotEmpty
-                        , ArchiveResult
-                        , ProcessError
-                        ]
-                       m
-                       ()
-installGHCBindist dlinfo ver installDir forceInstall = do
-  let tver = mkTVer ver
-
-  lift $ logDebug $ "Requested to install GHC with " <> prettyVer ver
-
-  regularGHCInstalled <- lift $ checkIfToolInstalled GHC ver
-
-  if
-    | not forceInstall
-    , regularGHCInstalled
-    , GHCupInternal <- installDir -> do
-        throwE $ AlreadyInstalled GHC ver
-
-    | forceInstall
-    , regularGHCInstalled
-    , GHCupInternal <- installDir -> do
-        lift $ logInfo "Removing the currently installed GHC version first!"
-        liftE $ rmGHCVer tver
-
-    | otherwise -> pure ()
-
-  -- download (or use cached version)
-  dl <- liftE $ downloadCached dlinfo Nothing
-
-
-  toolchainSanityChecks
-
-  case installDir of
-    IsolateDir isoDir -> do                        -- isolated install
-      lift $ logInfo $ "isolated installing GHC to " <> T.pack isoDir
-      liftE $ installPackedGHC dl (view dlSubdir dlinfo) (IsolateDirResolved isoDir) ver forceInstall
-    GHCupInternal -> do                            -- regular install
-      -- prepare paths
-      ghcdir <- lift $ ghcupGHCDir tver
-
-      liftE $ installPackedGHC dl (view dlSubdir dlinfo) (GHCupDir ghcdir) ver forceInstall
-
-      -- make symlinks & stuff when regular install,
-      liftE $ postGHCInstall tver
-
- where
-  toolchainSanityChecks = do
-    r <- forM ["CC", "LD"] (liftIO . lookupEnv)
-    case catMaybes r of
-      [] -> pure ()
-      _ -> do
-        lift $ logWarn $ "CC/LD environment variable is set. This will change the compiler/linker"
-         <> "\n" <> "GHC uses internally and can cause defunct GHC in some cases (e.g. in Anaconda"
-         <> "\n" <> "environments). If you encounter problems, unset CC and LD and reinstall."
-
-
--- | Install a packed GHC distribution. This only deals with unpacking and the GHC
--- build system and nothing else.
-installPackedGHC :: ( MonadMask m
-                    , MonadCatch m
-                    , MonadReader env m
-                    , HasDirs env
-                    , HasPlatformReq env
-                    , HasSettings env
-                    , MonadThrow m
-                    , HasLog env
-                    , MonadIO m
-                    , MonadUnliftIO m
-                    , MonadFail m
-                    )
-                 => FilePath          -- ^ Path to the packed GHC bindist
-                 -> Maybe TarDir      -- ^ Subdir of the archive
-                 -> InstallDirResolved
-                 -> Version           -- ^ The GHC version
-                 -> Bool              -- ^ Force install
-                 -> Excepts
-                      '[ BuildFailed
-                       , UnknownArchive
-                       , TarDirDoesNotExist
-                       , DirNotEmpty
-                       , ArchiveResult
-                       , ProcessError
-                       ] m ()
-installPackedGHC dl msubdir inst ver forceInstall = do
-  PlatformRequest {..} <- lift getPlatformReq
-
-  unless forceInstall
-    (liftE $ installDestSanityCheck inst)
-
-  -- unpack
-  tmpUnpack <- lift mkGhcupTmpDir
-  liftE $ cleanUpOnError tmpUnpack (unpackToDir tmpUnpack dl)
-  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform tmpUnpack
-
-  -- the subdir of the archive where we do the work
-  workdir <- maybe (pure tmpUnpack)
-                   (liftE . intoSubdir tmpUnpack)
-                   msubdir
-
-  liftE $ runBuildAction tmpUnpack
-                         (case inst of
-                           IsolateDirResolved _ -> Nothing -- don't clean up for isolated installs, since that'd potentially delete other
-                                                   -- user files if '--force' is supplied
-                           GHCupDir d -> Just d
-                           )
-                         (installUnpackedGHC workdir inst ver)
-
-
--- | Install an unpacked GHC distribution. This only deals with the GHC
--- build system and nothing else.
-installUnpackedGHC :: ( MonadReader env m
-                      , HasPlatformReq env
-                      , HasDirs env
-                      , HasSettings env
-                      , MonadThrow m
-                      , HasLog env
-                      , MonadIO m
-                      , MonadUnliftIO m
-                      , MonadMask m
-                      )
-                   => FilePath            -- ^ Path to the unpacked GHC bindist (where the configure script resides)
-                   -> InstallDirResolved  -- ^ Path to install to
-                   -> Version             -- ^ The GHC version
-                   -> Excepts '[ProcessError] m ()
-installUnpackedGHC path inst ver
-  | isWindows = do
-      lift $ logInfo "Installing GHC (this may take a while)"
-      -- Windows bindists are relocatable and don't need
-      -- to run configure.
-      -- We also must make sure to preserve mtime to not confuse ghc-pkg.
-      lift $ withRunInIO $ \run -> flip onException (case inst of
-                                                      IsolateDirResolved _ -> pure ()
-                                                      GHCupDir d -> run $ recyclePathForcibly d
-                                                    ) $ copyDirectoryRecursive path (fromInstallDir inst) $ \source dest -> do
-        mtime <- getModificationTime source
-        moveFilePortable source dest
-        setModificationTime dest mtime
-  | otherwise = do
-      PlatformRequest {..} <- lift getPlatformReq
-
-      let alpineArgs
-           | ver >= [vver|8.2.2|], Linux Alpine <- _rPlatform
-           = ["--disable-ld-override"]
-           | otherwise
-           = []
-
-      lift $ logInfo "Installing GHC (this may take a while)"
-      lEM $ execLogged "sh"
-                       ("./configure" : ("--prefix=" <> fromInstallDir inst)
-                        : alpineArgs
-                       )
-                       (Just path)
-                       "ghc-configure"
-                       Nothing
-      lEM $ make ["install"] (Just path)
-      pure ()
-
-
--- | Installs GHC into @~\/.ghcup\/ghc/\<ver\>@ and places the
--- following symlinks in @~\/.ghcup\/bin@:
---
---   * @ghc-x.y.z -> ..\/ghc\/x.y.z\/bin/ghc@
---   * @ghc-x.y   -> ..\/ghc\/x.y.z\/bin/ghc@ (if x.y.z is the latest x.y version)
-installGHCBin :: ( MonadFail m
-                 , MonadMask m
-                 , MonadCatch m
-                 , MonadReader env m
-                 , HasPlatformReq env
-                 , HasGHCupInfo env
-                 , HasDirs env
-                 , HasSettings env
-                 , HasLog env
-                 , MonadResource m
-                 , MonadIO m
-                 , MonadUnliftIO m
-                 )
-              => Version         -- ^ the version to install
-              -> InstallDir
-              -> Bool            -- ^ force install
-              -> Excepts
-                   '[ AlreadyInstalled
-                    , BuildFailed
-                    , DigestError
-                    , GPGError
-                    , DownloadFailed
-                    , NoDownload
-                    , NotInstalled
-                    , UnknownArchive
-                    , TarDirDoesNotExist
-                    , DirNotEmpty
-                    , ArchiveResult
-                    , ProcessError
-                    ]
-                   m
-                   ()
-installGHCBin ver installDir forceInstall = do
-  dlinfo <- liftE $ getDownloadInfo GHC ver
-  liftE $ installGHCBindist dlinfo ver installDir forceInstall
-
-
--- | Like 'installCabalBin', except takes the 'DownloadInfo' as
--- argument instead of looking it up from 'GHCupDownloads'.
-installCabalBindist :: ( MonadMask m
-                       , MonadCatch m
-                       , MonadReader env m
-                       , HasPlatformReq env
-                       , HasDirs env
-                       , HasSettings env
-                       , HasLog env
-                       , MonadResource m
-                       , MonadIO m
-                       , MonadUnliftIO m
-                       , MonadFail m
-                       )
-                    => DownloadInfo
-                    -> Version
-                    -> InstallDir
-                    -> Bool           -- ^ Force install
-                    -> Excepts
-                         '[ AlreadyInstalled
-                          , CopyError
-                          , DigestError
-                          , GPGError
-                          , DownloadFailed
-                          , NoDownload
-                          , NotInstalled
-                          , UnknownArchive
-                          , TarDirDoesNotExist
-                          , ArchiveResult
-                          , FileAlreadyExistsError
-                          ]
-                         m
-                         ()
-installCabalBindist dlinfo ver installDir forceInstall = do
-  lift $ logDebug $ "Requested to install cabal version " <> prettyVer ver
-
-  PlatformRequest {..} <- lift getPlatformReq
-  Dirs {..} <- lift getDirs
-
-  -- check if we already have a regular cabal already installed
-  regularCabalInstalled <- lift $ checkIfToolInstalled Cabal ver
-
-  if
-    | not forceInstall
-    , regularCabalInstalled
-    , GHCupInternal <- installDir -> do
-        throwE $ AlreadyInstalled Cabal ver
-
-    | forceInstall
-    , regularCabalInstalled
-    , GHCupInternal <- installDir -> do
-        lift $ logInfo "Removing the currently installed version first!"
-        liftE $ rmCabalVer ver
-
-    | otherwise -> pure ()
-
-
-  -- download (or use cached version)
-  dl <- liftE $ downloadCached dlinfo Nothing
-
-  -- unpack
-  tmpUnpack <- lift withGHCupTmpDir
-  liftE $ cleanUpOnError tmpUnpack (unpackToDir tmpUnpack dl)
-  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform tmpUnpack
-
-  -- the subdir of the archive where we do the work
-  workdir <- maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
-
-  case installDir of
-    IsolateDir isoDir -> do             -- isolated install
-      lift $ logInfo $ "isolated installing Cabal to " <> T.pack isoDir
-      liftE $ installCabalUnpacked workdir (IsolateDirResolved isoDir) ver forceInstall
-
-    GHCupInternal -> do                 -- regular install
-      liftE $ installCabalUnpacked workdir (GHCupDir binDir) ver forceInstall
-
-
--- | Install an unpacked cabal distribution.Symbol
-installCabalUnpacked :: (MonadCatch m, HasLog env, MonadIO m, MonadReader env m)
-              => FilePath      -- ^ Path to the unpacked cabal bindist (where the executable resides)
-              -> InstallDirResolved      -- ^ Path to install to
-              -> Version
-              -> Bool          -- ^ Force Install
-              -> Excepts '[CopyError, FileAlreadyExistsError] m ()
-installCabalUnpacked path inst ver forceInstall = do
-  lift $ logInfo "Installing cabal"
-  let cabalFile = "cabal"
-  liftIO $ createDirRecursive' (fromInstallDir inst)
-  let destFileName = cabalFile
-        <> (case inst of
-              IsolateDirResolved _ -> ""
-              GHCupDir _ -> ("-" <>) . T.unpack . prettyVer $ ver
-           )
-        <> exeExt
-  let destPath = fromInstallDir inst </> destFileName
-
-  unless forceInstall          -- Overwrite it when it IS a force install
-    (liftE $ throwIfFileAlreadyExists destPath)
-
-  copyFileE
-    (path </> cabalFile <> exeExt)
-    destPath
-  lift $ chmod_755 destPath
-
--- | Installs cabal into @~\/.ghcup\/bin/cabal-\<ver\>@ and
--- creates a default @cabal -> cabal-x.y.z.q@ symlink for
--- the latest installed version.
-installCabalBin :: ( MonadMask m
-                   , MonadCatch m
-                   , MonadReader env m
-                   , HasPlatformReq env
-                   , HasGHCupInfo env
-                   , HasDirs env
-                   , HasSettings env
-                   , HasLog env
-                   , MonadResource m
-                   , MonadIO m
-                   , MonadUnliftIO m
-                   , MonadFail m
-                   )
-                => Version
-                -> InstallDir
-                -> Bool           -- force install
-                -> Excepts
-                     '[ AlreadyInstalled
-                      , CopyError
-                      , DigestError
-                      , GPGError
-                      , DownloadFailed
-                      , NoDownload
-                      , NotInstalled
-                      , UnknownArchive
-                      , TarDirDoesNotExist
-                      , ArchiveResult
-                      , FileAlreadyExistsError
-                      ]
-                     m
-                     ()
-installCabalBin ver installDir forceInstall = do
-  dlinfo <- liftE $ getDownloadInfo Cabal ver
-  installCabalBindist dlinfo ver installDir forceInstall
-
-
--- | Like 'installHLSBin, except takes the 'DownloadInfo' as
--- argument instead of looking it up from 'GHCupDownloads'.
-installHLSBindist :: ( MonadMask m
-                     , MonadCatch m
-                     , MonadReader env m
-                     , HasPlatformReq env
-                     , HasDirs env
-                     , HasSettings env
-                     , HasLog env
-                     , MonadResource m
-                     , MonadIO m
-                     , MonadUnliftIO m
-                     , MonadFail m
-                     )
-                  => DownloadInfo
-                  -> Version
-                  -> InstallDir -- ^ isolated install path, if user passed any
-                  -> Bool       -- ^ Force install
-                  -> Excepts
-                       '[ AlreadyInstalled
-                        , CopyError
-                        , DigestError
-                        , GPGError
-                        , DownloadFailed
-                        , NoDownload
-                        , NotInstalled
-                        , UnknownArchive
-                        , TarDirDoesNotExist
-                        , ArchiveResult
-                        , FileAlreadyExistsError
-                        , ProcessError
-                        , DirNotEmpty
-                        ]
-                       m
-                       ()
-installHLSBindist dlinfo ver installDir forceInstall = do
-  lift $ logDebug $ "Requested to install hls version " <> prettyVer ver
-
-  PlatformRequest {..} <- lift getPlatformReq
-  Dirs {..} <- lift getDirs
-
-  regularHLSInstalled <- lift $ checkIfToolInstalled HLS ver
-
-  if
-    | not forceInstall
-    , regularHLSInstalled
-    , GHCupInternal <- installDir -> do        -- regular install
-        throwE $ AlreadyInstalled HLS ver
-
-    | forceInstall
-    , regularHLSInstalled
-    , GHCupInternal <- installDir -> do        -- regular forced install
-        lift $ logInfo "Removing the currently installed version of HLS before force installing!"
-        liftE $ rmHLSVer ver
-
-    | otherwise -> pure ()
-
-  -- download (or use cached version)
-  dl <- liftE $ downloadCached dlinfo Nothing
-
-  -- unpack
-  tmpUnpack <- lift withGHCupTmpDir
-  liftE $ cleanUpOnError tmpUnpack (unpackToDir tmpUnpack dl)
-  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform tmpUnpack
-
-  -- the subdir of the archive where we do the work
-  workdir <- maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
-  legacy <- liftIO $ isLegacyHLSBindist workdir
-
-  if
-    | not forceInstall
-    , not legacy
-    , (IsolateDir fp) <- installDir -> liftE $ installDestSanityCheck (IsolateDirResolved fp)
-    | otherwise -> pure ()
-
-  case installDir of
-    IsolateDir isoDir -> do
-      lift $ logInfo $ "isolated installing HLS to " <> T.pack isoDir
-      if legacy
-      then liftE $ installHLSUnpackedLegacy workdir (IsolateDirResolved isoDir) ver forceInstall
-      else liftE $ runBuildAction tmpUnpack Nothing $ installHLSUnpacked workdir (IsolateDirResolved isoDir) ver
-
-    GHCupInternal -> do
-      if legacy
-      then liftE $ installHLSUnpackedLegacy workdir (GHCupDir binDir) ver forceInstall
-      else do
-        inst <- ghcupHLSDir ver
-        liftE $ runBuildAction tmpUnpack (Just inst)
-              $ installHLSUnpacked workdir (GHCupDir inst) ver
-        liftE $ setHLS ver SetHLS_XYZ Nothing
-
-
-isLegacyHLSBindist :: FilePath -- ^ Path to the unpacked hls bindist
-                   -> IO Bool
-isLegacyHLSBindist path = do
-  not <$> doesFileExist (path </> "GNUmakefile")
-
--- | Install an unpacked hls distribution.
-installHLSUnpacked :: (MonadMask m, MonadUnliftIO m, MonadReader env m, MonadFail m, HasLog env, HasDirs env, HasSettings env, MonadCatch m, MonadIO m)
-                   => FilePath      -- ^ Path to the unpacked hls bindist (where the executable resides)
-                   -> InstallDirResolved      -- ^ Path to install to
-                   -> Version
-                   -> Excepts '[ProcessError, CopyError, FileAlreadyExistsError, NotInstalled] m ()
-installHLSUnpacked path (fromInstallDir -> inst) _ = do
-  lift $ logInfo "Installing HLS"
-  liftIO $ createDirRecursive' inst
-  lEM $ make ["PREFIX=" <> inst, "install"] (Just path)
-
--- | Install an unpacked hls distribution (legacy).
-installHLSUnpackedLegacy :: (MonadReader env m, MonadFail m, HasLog env, MonadCatch m, MonadIO m)
-                         => FilePath      -- ^ Path to the unpacked hls bindist (where the executable resides)
-                         -> InstallDirResolved      -- ^ Path to install to
-                         -> Version
-                         -> Bool          -- ^ is it a force install
-                         -> Excepts '[CopyError, FileAlreadyExistsError] m ()
-installHLSUnpackedLegacy path installDir ver forceInstall = do
-  lift $ logInfo "Installing HLS"
-  liftIO $ createDirRecursive' (fromInstallDir installDir)
-
-  -- install haskell-language-server-<ghcver>
-  bins@(_:_) <- liftIO $ findFiles
-    path
-    (makeRegexOpts compExtended
-                   execBlank
-                   ([s|^haskell-language-server-[0-9].*$|] :: ByteString)
-    )
-  forM_ bins $ \f -> do
-    let toF = dropSuffix exeExt f
-              <> (case installDir of
-                   IsolateDirResolved _ -> ""
-                   GHCupDir _ -> ("~" <>) . T.unpack . prettyVer $ ver
-                 )
-              <> exeExt
-
-    let srcPath = path </> f
-    let destPath = fromInstallDir installDir </> toF
-
-    unless forceInstall   -- if it is a force install, overwrite it.
-      (liftE $ throwIfFileAlreadyExists destPath)
-
-    copyFileE
-      srcPath
-      destPath
-    lift $ chmod_755 destPath
-
-  -- install haskell-language-server-wrapper
-  let wrapper = "haskell-language-server-wrapper"
-      toF = wrapper
-            <> (case installDir of
-                 IsolateDirResolved _ -> ""
-                 GHCupDir _ -> ("-" <>) . T.unpack . prettyVer $ ver
-               )
-            <> exeExt
-      srcWrapperPath = path </> wrapper <> exeExt
-      destWrapperPath = fromInstallDir installDir </> toF
-
-  unless forceInstall
-    (liftE $ throwIfFileAlreadyExists destWrapperPath)
-
-  copyFileE
-    srcWrapperPath
-    destWrapperPath
-
-  lift $ chmod_755 destWrapperPath
-
-
-
--- | Installs hls binaries @haskell-language-server-\<ghcver\>@
--- into @~\/.ghcup\/bin/@, as well as @haskell-languager-server-wrapper@.
-installHLSBin :: ( MonadMask m
-                 , MonadCatch m
-                 , MonadReader env m
-                 , HasPlatformReq env
-                 , HasGHCupInfo env
-                 , HasDirs env
-                 , HasSettings env
-                 , HasLog env
-                 , MonadResource m
-                 , MonadIO m
-                 , MonadUnliftIO m
-                 , MonadFail m
-                 )
-              => Version
-              -> InstallDir
-              -> Bool            -- force install
-              -> Excepts
-                   '[ AlreadyInstalled
-                    , CopyError
-                    , DigestError
-                    , GPGError
-                    , DownloadFailed
-                    , NoDownload
-                    , NotInstalled
-                    , UnknownArchive
-                    , TarDirDoesNotExist
-                    , ArchiveResult
-                    , FileAlreadyExistsError
-                    , ProcessError
-                    , DirNotEmpty
-                    ]
-                   m
-                   ()
-installHLSBin ver installDir forceInstall = do
-  dlinfo <- liftE $ getDownloadInfo HLS ver
-  installHLSBindist dlinfo ver installDir forceInstall
-
-
-compileHLS :: ( MonadMask m
-              , MonadCatch m
-              , MonadReader env m
-              , HasDirs env
-              , HasSettings env
-              , HasPlatformReq env
-              , HasGHCupInfo env
-              , HasLog env
-              , MonadResource m
-              , MonadIO m
-              , MonadUnliftIO m
-              , MonadFail m
-              )
-           => Either Version GitBranch
-           -> [Version]
-           -> Maybe Int
-           -> Maybe Version
-           -> InstallDir
-           -> Maybe (Either FilePath URI)
-           -> Maybe URI
-           -> Maybe (Either FilePath [URI])  -- ^ patches
-           -> [Text]                   -- ^ additional args to cabal install
-           -> Excepts '[ NoDownload
-                       , GPGError
-                       , DownloadFailed
-                       , DigestError
-                       , UnknownArchive
-                       , TarDirDoesNotExist
-                       , ArchiveResult
-                       , BuildFailed
-                       , NotInstalled
-                       ] m Version
-compileHLS targetHLS ghcs jobs ov installDir cabalProject cabalProjectLocal patches cabalArgs = do
-  PlatformRequest { .. } <- lift getPlatformReq
-  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
-  Dirs { .. } <- lift getDirs
-
-
-  (workdir, tver) <- case targetHLS of
-    -- unpack from version tarball
-    Left tver -> do
-      lift $ logDebug $ "Requested to compile: " <> prettyVer tver
-
-      -- download source tarball
-      dlInfo <-
-        preview (ix HLS % ix tver % viSourceDL % _Just) dls
-          ?? NoDownload
-      dl <- liftE $ downloadCached dlInfo Nothing
-
-      -- unpack
-      tmpUnpack <- lift mkGhcupTmpDir
-      liftE $ cleanUpOnError tmpUnpack (unpackToDir tmpUnpack dl)
-      liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform tmpUnpack
-
-      workdir <- maybe (pure tmpUnpack)
-                       (liftE . intoSubdir tmpUnpack)
-                       (view dlSubdir dlInfo)
-
-      pure (workdir, tver)
-
-    -- clone from git
-    Right GitBranch{..} -> do
-      tmpUnpack <- lift mkGhcupTmpDir
-      let git args = execLogged "git" ("--no-pager":args) (Just tmpUnpack) "git" Nothing
-      tver <- reThrowAll @_ @'[ProcessError] DownloadFailed $ do
-        let rep = fromMaybe "https://github.com/haskell/haskell-language-server.git" repo
-        lift $ logInfo $ "Fetching git repo " <> T.pack rep <> " at ref " <> T.pack ref <> " (this may take a while)"
-        lEM $ git [ "init" ]
-        lEM $ git [ "remote"
-                  , "add"
-                  , "origin"
-                  , fromString rep ]
-
-        let fetch_args =
-                  [ "fetch"
-                  , "--depth"
-                  , "1"
-                  , "--quiet"
-                  , "origin"
-                  , fromString ref ]
-        lEM $ git fetch_args
-
-        lEM $ git [ "checkout", "FETCH_HEAD" ]
-        (Just gpd) <- parseGenericPackageDescriptionMaybe <$> liftIO (B.readFile (tmpUnpack </> "haskell-language-server.cabal"))
-        pure . (\c -> Version Nothing c [] Nothing)
-          . NE.fromList . fmap (NE.fromList . (:[]) . digits . fromIntegral)
-          . versionNumbers
-          . pkgVersion
-          . package
-          . packageDescription
-          $ gpd
-
-      liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform tmpUnpack
-      lift $ logInfo $ "Git version " <> T.pack ref <> " corresponds to HLS version " <> prettyVer tver
-
-      pure (tmpUnpack, tver)
-
-  -- the version that's installed may differ from the
-  -- compiled version, so the user can overwrite it
-  let installVer = fromMaybe tver ov
-
-  liftE $ runBuildAction
-    workdir
-    Nothing
-    (reThrowAll @_ @'[GPGError, DownloadFailed, DigestError, PatchFailed, ProcessError, FileAlreadyExistsError, CopyError] @'[BuildFailed] (BuildFailed workdir) $ do
-      let tmpInstallDir = workdir </> "out"
-      liftIO $ createDirRecursive' tmpInstallDir
-
-      -- apply patches
-      liftE $ applyAnyPatch patches workdir
-
-      -- set up project files
-      cp <- case cabalProject of
-        Just (Left cp)
-          | isAbsolute cp -> do
-              copyFileE cp (workdir </> "cabal.project")
-              pure "cabal.project"
-          | otherwise -> pure (takeFileName cp)
-        Just (Right uri) -> do
-          tmpUnpack <- lift withGHCupTmpDir
-          cp <- liftE $ download uri Nothing Nothing tmpUnpack (Just "cabal.project") False
-          copyFileE cp (workdir </> "cabal.project")
-          pure "cabal.project"
-        Nothing -> pure "cabal.project"
-      forM_ cabalProjectLocal $ \uri -> do
-        tmpUnpack <- lift withGHCupTmpDir
-        cpl <- liftE $ download uri Nothing Nothing tmpUnpack (Just (cp <.> "local")) False
-        copyFileE cpl (workdir </> cp <.> "local")
-      artifacts <- forM (sort ghcs) $ \ghc -> do
-        let ghcInstallDir = tmpInstallDir </> T.unpack (prettyVer ghc)
-        liftIO $ createDirRecursive' tmpInstallDir
-        lift $ logInfo $ "Building HLS " <> prettyVer installVer <> " for GHC version " <> prettyVer ghc
-        liftE $ lEM @_ @'[ProcessError] $
-          execLogged "cabal" ( [ "v2-install"
-                               , "-w"
-                               , "ghc-" <> T.unpack (prettyVer ghc)
-                               , "--install-method=copy"
-                               ] ++
-                               maybe [] (\j -> ["--jobs=" <> show j]) jobs ++
-                               [ "--overwrite-policy=always"
-                               , "--disable-profiling"
-                               , "--disable-tests"
-                               , "--installdir=" <> ghcInstallDir
-                               , "--project-file=" <> cp
-                               ] ++ fmap T.unpack cabalArgs ++ [
-                                 "exe:haskell-language-server"
-                               , "exe:haskell-language-server-wrapper"]
-                             )
-          (Just workdir) "cabal" Nothing
-        pure ghcInstallDir
-
-      forM_ artifacts $ \artifact -> do
-        liftIO $ renameFile (artifact </> "haskell-language-server" <.> exeExt)
-          (tmpInstallDir </> "haskell-language-server-" <> takeFileName artifact <.> exeExt)
-        liftIO $ renameFile (artifact </> "haskell-language-server-wrapper" <.> exeExt)
-          (tmpInstallDir </> "haskell-language-server-wrapper" <.> exeExt)
-        liftIO $ rmPathForcibly artifact
-
-      case installDir of
-        IsolateDir isoDir -> do
-          lift $ logInfo $ "isolated installing HLS to " <> T.pack isoDir
-          liftE $ installHLSUnpackedLegacy tmpInstallDir (IsolateDirResolved isoDir) installVer True
-        GHCupInternal -> do
-          liftE $ installHLSUnpackedLegacy tmpInstallDir (GHCupDir binDir) installVer True
-    )
-
-  pure installVer
-
-
-
--- | Installs stack into @~\/.ghcup\/bin/stack-\<ver\>@ and
--- creates a default @stack -> stack-x.y.z.q@ symlink for
--- the latest installed version.
-installStackBin :: ( MonadMask m
-                   , MonadCatch m
-                   , MonadReader env m
-                   , HasDirs env
-                   , HasSettings env
-                   , HasPlatformReq env
-                   , HasGHCupInfo env
-                   , HasLog env
-                   , MonadResource m
-                   , MonadIO m
-                   , MonadUnliftIO m
-                   , MonadFail m
-                   )
-                => Version
-                -> InstallDir
-                -> Bool            -- ^ Force install
-                -> Excepts
-                     '[ AlreadyInstalled
-                      , CopyError
-                      , DigestError
-                      , GPGError
-                      , DownloadFailed
-                      , NoDownload
-                      , NotInstalled
-                      , UnknownArchive
-                      , TarDirDoesNotExist
-                      , ArchiveResult
-                      , FileAlreadyExistsError
-                      ]
-                     m
-                     ()
-installStackBin ver installDir forceInstall = do
-  dlinfo <- liftE $ getDownloadInfo Stack ver
-  installStackBindist dlinfo ver installDir forceInstall
-
-
--- | Like 'installStackBin', except takes the 'DownloadInfo' as
--- argument instead of looking it up from 'GHCupDownloads'.
-installStackBindist :: ( MonadMask m
-                       , MonadCatch m
-                       , MonadReader env m
-                       , HasPlatformReq env
-                       , HasDirs env
-                       , HasSettings env
-                       , HasLog env
-                       , MonadResource m
-                       , MonadIO m
-                       , MonadUnliftIO m
-                       , MonadFail m
-                       )
-                    => DownloadInfo
-                    -> Version
-                    -> InstallDir
-                    -> Bool           -- ^ Force install
-                    -> Excepts
-                         '[ AlreadyInstalled
-                          , CopyError
-                          , DigestError
-                          , GPGError
-                          , DownloadFailed
-                          , NoDownload
-                          , NotInstalled
-                          , UnknownArchive
-                          , TarDirDoesNotExist
-                          , ArchiveResult
-                          , FileAlreadyExistsError
-                          ]
-                         m
-                         ()
-installStackBindist dlinfo ver installDir forceInstall = do
-  lift $ logDebug $ "Requested to install stack version " <> prettyVer ver
-
-  PlatformRequest {..} <- lift getPlatformReq
-  Dirs {..} <- lift getDirs
-
-  regularStackInstalled <- lift $ checkIfToolInstalled Stack ver
-
-  if
-    | not forceInstall
-    , regularStackInstalled
-    , GHCupInternal <- installDir -> do
-        throwE $ AlreadyInstalled Stack ver
-
-    | forceInstall
-    , regularStackInstalled
-    , GHCupInternal <- installDir -> do
-        lift $ logInfo "Removing the currently installed version of Stack first!"
-        liftE $ rmStackVer ver
-
-    | otherwise -> pure ()
-
-  -- download (or use cached version)
-  dl <- liftE $ downloadCached dlinfo Nothing
-
-  -- unpack
-  tmpUnpack <- lift withGHCupTmpDir
-  liftE $ cleanUpOnError tmpUnpack (unpackToDir tmpUnpack dl)
-  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform tmpUnpack
-
-  -- the subdir of the archive where we do the work
-  workdir <- maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
-
-  case installDir of
-    IsolateDir isoDir -> do                 -- isolated install
-      lift $ logInfo $ "isolated installing Stack to " <> T.pack isoDir
-      liftE $ installStackUnpacked workdir (IsolateDirResolved isoDir) ver forceInstall
-    GHCupInternal -> do                     -- regular install
-      liftE $ installStackUnpacked workdir (GHCupDir binDir) ver forceInstall
-
-
--- | Install an unpacked stack distribution.
-installStackUnpacked :: (MonadReader env m, HasLog env, MonadCatch m, MonadIO m)
-              => FilePath      -- ^ Path to the unpacked stack bindist (where the executable resides)
-              -> InstallDirResolved
-              -> Version
-              -> Bool          -- ^ Force install
-              -> Excepts '[CopyError, FileAlreadyExistsError] m ()
-installStackUnpacked path installDir ver forceInstall = do
-  lift $ logInfo "Installing stack"
-  let stackFile = "stack"
-  liftIO $ createDirRecursive' (fromInstallDir installDir)
-  let destFileName = stackFile
-                     <> (case installDir of
-                          IsolateDirResolved _ -> ""
-                          GHCupDir _ -> ("-" <>) .  T.unpack . prettyVer $ ver
-                        )
-                     <> exeExt
-      destPath = fromInstallDir installDir </> destFileName
-
-  unless forceInstall
-    (liftE $ throwIfFileAlreadyExists destPath)
-
-  copyFileE
-    (path </> stackFile <> exeExt)
-    destPath
-  lift $ chmod_755 destPath
-
-
-    ---------------------
-    --[ Set GHC/cabal ]--
-    ---------------------
-
-
-
--- | Set GHC symlinks in @~\/.ghcup\/bin@ for the requested GHC version. The behavior depends
--- on `SetGHC`:
---
---   * SetGHCOnly: @~\/.ghcup\/bin\/ghc -> ~\/.ghcup\/ghc\/\<ver\>\/bin\/ghc@
---   * SetGHC_XY: @~\/.ghcup\/bin\/ghc-X.Y -> ~\/.ghcup\/ghc\/\<ver\>\/bin\/ghc@
---   * SetGHC_XYZ: @~\/.ghcup\/bin\/ghc-\<ver\> -> ~\/.ghcup\/ghc\/\<ver\>\/bin\/ghc@
---
--- Additionally creates a @~\/.ghcup\/share -> ~\/.ghcup\/ghc\/\<ver\>\/share symlink@
--- for 'SetGHCOnly' constructor.
-setGHC :: ( MonadReader env m
-          , HasDirs env
-          , HasLog env
-          , MonadThrow m
-          , MonadFail m
-          , MonadIO m
-          , MonadCatch m
-          , MonadMask m
-          , MonadUnliftIO m
-          )
-       => GHCTargetVersion
-       -> SetGHC
-       -> Maybe FilePath  -- if set, signals that we're not operating in ~/.ghcup/bin
-                          -- and don't want mess with other versions
-       -> Excepts '[NotInstalled] m GHCTargetVersion
-setGHC ver sghc mBinDir = do
-  let verS = T.unpack $ prettyVer (_tvVersion ver)
-  ghcdir                        <- lift $ ghcupGHCDir ver
-
-  whenM (lift $ not <$> ghcInstalled ver) (throwE (NotInstalled GHC ver))
-
-  -- symlink destination
-  binDir <- case mBinDir of
-    Just x -> pure x
-    Nothing -> do
-      Dirs {binDir = f} <- lift getDirs
-      pure f
-
-  -- first delete the old symlinks (this fixes compatibility issues
-  -- with old ghcup)
-  when (isNothing mBinDir) $
-    case sghc of
-      SetGHCOnly -> liftE $ rmPlainGHC (_tvTarget ver)
-      SetGHC_XY  -> liftE $ rmMajorGHCSymlinks ver
-      SetGHC_XYZ -> liftE $ rmMinorGHCSymlinks ver
-
-  -- for ghc tools (ghc, ghci, haddock, ...)
-  verfiles <- ghcToolFiles ver
-  forM_ verfiles $ \file -> do
-    mTargetFile <- case sghc of
-      SetGHCOnly -> pure $ Just file
-      SetGHC_XY  -> do
-        handle
-            (\(e :: ParseError) -> lift $ logWarn (T.pack $ displayException e) >> pure Nothing)
-          $ do
-            (mj, mi) <- getMajorMinorV (_tvVersion ver)
-            let major' = intToText mj <> "." <> intToText mi
-            pure $ Just (file <> "-" <> T.unpack major')
-      SetGHC_XYZ ->
-        pure $ Just (file <> "-" <> verS)
-
-    -- create symlink
-    forM_ mTargetFile $ \targetFile -> do
-      bindir <- ghcInternalBinDir ver
-      let fullF = binDir </> targetFile  <> exeExt
-          fileWithExt = bindir </> file <> exeExt
-      destL <- binarySymLinkDestination binDir fileWithExt
-      lift $ createLink destL fullF
-
-  when (isNothing mBinDir) $ do
-    -- create symlink for share dir
-    when (isNothing . _tvTarget $ ver) $ lift $ symlinkShareDir ghcdir verS
-
-    when (sghc == SetGHCOnly) $ lift warnAboutHlsCompatibility
-
-  pure ver
-
- where
-
-  symlinkShareDir :: ( MonadReader env m
-                     , HasDirs env
-                     , MonadIO m
-                     , HasLog env
-                     , MonadCatch m
-                     , MonadMask m
-                     )
-                  => FilePath
-                  -> String
-                  -> m ()
-  symlinkShareDir ghcdir ver' = do
-    Dirs {..} <- getDirs
-    let destdir = baseDir
-    case sghc of
-      SetGHCOnly -> do
-        let sharedir     = "share"
-        let fullsharedir = ghcdir </> sharedir
-        logDebug $ "Checking for sharedir existence: " <> T.pack fullsharedir
-        whenM (liftIO $ doesDirectoryExist fullsharedir) $ do
-          let fullF   = destdir </> sharedir
-          let targetF = "." </> "ghc" </> ver' </> sharedir
-          logDebug $ "rm -f " <> T.pack fullF
-          hideError doesNotExistErrorType $ rmDirectoryLink fullF
-          logDebug $ "ln -s " <> T.pack targetF <> " " <> T.pack fullF
-
-          if isWindows
-          then liftIO
-                 -- On windows we need to be more permissive
-                 -- in case symlinks can't be created, be just
-                 -- give up here. This symlink isn't strictly necessary.
-                 $ hideError permissionErrorType
-                 $ hideError illegalOperationErrorType
-                 $ createDirectoryLink targetF fullF
-          else liftIO
-                 $ createDirectoryLink targetF fullF
-      _ -> pure ()
-
-unsetGHC :: ( MonadReader env m
-            , HasDirs env
-            , HasLog env
-            , MonadThrow m
-            , MonadFail m
-            , MonadIO m
-            , MonadMask m
-            )
-         => Maybe Text
-         -> Excepts '[NotInstalled] m ()
-unsetGHC = rmPlainGHC
-
-
--- | Set the @~\/.ghcup\/bin\/cabal@ symlink.
-setCabal :: ( MonadMask m
-            , MonadReader env m
-            , HasDirs env
-            , HasLog env
-            , MonadFail m
-            , MonadIO m
-            , MonadUnliftIO m)
-         => Version
-         -> Excepts '[NotInstalled] m ()
-setCabal ver = do
-  let targetFile = "cabal-" <> T.unpack (prettyVer ver) <> exeExt
-
-  -- symlink destination
-  Dirs {..} <- lift getDirs
-
-  whenM (liftIO $ not <$> doesFileExist (binDir </> targetFile))
-    $ throwE
-    $ NotInstalled Cabal (GHCTargetVersion Nothing ver)
-
-  let cabalbin = binDir </> "cabal" <> exeExt
-
-  -- create link
-  let destL = targetFile
-  lift $ createLink destL cabalbin
-
-  pure ()
-
-unsetCabal :: ( MonadMask m
-              , MonadReader env m
-              , HasDirs env
-              , MonadIO m)
-           => m ()
-unsetCabal = do
-  Dirs {..} <- getDirs
-  let cabalbin = binDir </> "cabal" <> exeExt
-  hideError doesNotExistErrorType $ rmLink cabalbin
-
-
--- | Set the haskell-language-server symlinks.
-setHLS :: ( MonadReader env m
-          , HasDirs env
-          , HasLog env
-          , MonadIO m
-          , MonadMask m
-          , MonadFail m
-          , MonadUnliftIO m
-          )
-       => Version
-       -> SetHLS
-       -> Maybe FilePath  -- if set, signals that we're not operating in ~/.ghcup/bin
-                          -- and don't want mess with other versions
-       -> Excepts '[NotInstalled] m ()
-setHLS ver shls mBinDir = do
-  whenM (lift $ not <$> hlsInstalled ver) (throwE (NotInstalled HLS (GHCTargetVersion Nothing ver)))
-
-  -- symlink destination
-  binDir <- case mBinDir of
-    Just x -> pure x
-    Nothing -> do
-      Dirs {binDir = f} <- lift getDirs
-      pure f
-
-  -- first delete the old symlinks
-  when (isNothing mBinDir) $
-    case shls of
-      -- not for legacy
-      SetHLS_XYZ -> liftE $ rmMinorHLSSymlinks ver
-      -- legacy and new
-      SetHLSOnly -> liftE rmPlainHLS
-
-  case shls of
-    -- not for legacy
-    SetHLS_XYZ -> do
-      bins <- lift $ hlsInternalServerScripts ver Nothing
-
-      forM_ bins $ \f -> do
-        let fname = takeFileName f
-        destL <- binarySymLinkDestination binDir f
-        let target = if "haskell-language-server-wrapper" `isPrefixOf` fname
-                     then fname <> "-" <> T.unpack (prettyVer ver) <> exeExt
-                     else fname <> "~" <> T.unpack (prettyVer ver) <> exeExt
-        lift $ createLink destL (binDir </> target)
-
-    -- legacy and new
-    SetHLSOnly -> do
-      -- set haskell-language-server-<ghcver> symlinks
-      bins <- lift $ hlsServerBinaries ver Nothing
-      when (null bins) $ throwE $ NotInstalled HLS (GHCTargetVersion Nothing ver)
-
-      forM_ bins $ \f -> do
-        let destL = f
-        let target = (<> exeExt) . head . splitOn "~" $ f
-        lift $ createLink destL (binDir </> target)
-
-      -- set haskell-language-server-wrapper symlink
-      let destL = "haskell-language-server-wrapper-" <> T.unpack (prettyVer ver) <> exeExt
-      let wrapper = binDir </> "haskell-language-server-wrapper" <> exeExt
-
-      lift $ createLink destL wrapper
-
-      when (isNothing mBinDir) $
-        lift warnAboutHlsCompatibility
-
-
-unsetHLS :: ( MonadMask m
-            , MonadReader env m
-            , HasDirs env
-            , MonadIO m)
-         => m ()
-unsetHLS = do
-  Dirs {..} <- getDirs
-  let wrapper = binDir </> "haskell-language-server-wrapper" <> exeExt
-  bins   <- liftIO $ handleIO (\_ -> pure []) $ findFiles'
-    binDir
-    (MP.chunk "haskell-language-server-" <* pvp' <* MP.chunk (T.pack exeExt) <* MP.eof)
-  forM_ bins (hideError doesNotExistErrorType . rmLink . (binDir </>))
-  hideError doesNotExistErrorType $ rmLink wrapper
-
-
--- | Set the @~\/.ghcup\/bin\/stack@ symlink.
-setStack :: ( MonadMask m
-            , MonadReader env m
-            , HasDirs env
-            , HasLog env
-            , MonadThrow m
-            , MonadFail m
-            , MonadIO m
-            , MonadUnliftIO m
-            )
-         => Version
-         -> Excepts '[NotInstalled] m ()
-setStack ver = do
-  let targetFile = "stack-" <> T.unpack (prettyVer ver) <> exeExt
-
-  -- symlink destination
-  Dirs {..} <- lift getDirs
-
-  whenM (liftIO $ not <$> doesFileExist (binDir </> targetFile))
-    $ throwE
-    $ NotInstalled Stack (GHCTargetVersion Nothing ver)
-
-  let stackbin = binDir </> "stack" <> exeExt
-
-  lift $ createLink targetFile stackbin
-
-  pure ()
-
-
-unsetStack :: ( MonadMask m
-              , MonadReader env m
-              , HasDirs env
-              , MonadIO m)
-           => m ()
-unsetStack = do
-  Dirs {..} <- getDirs
-  let stackbin = binDir </> "stack" <> exeExt
-  hideError doesNotExistErrorType $ rmLink stackbin
-
-
--- | Warn if the installed and set HLS is not compatible with the installed and
--- set GHC version.
-warnAboutHlsCompatibility :: ( MonadReader env m
-                             , HasDirs env
-                             , HasLog env
-                             , MonadThrow m
-                             , MonadCatch m
-                             , MonadIO m
-                             )
-                          => m ()
-warnAboutHlsCompatibility = do
-  supportedGHC <- hlsGHCVersions
-  currentGHC   <- fmap _tvVersion <$> ghcSet Nothing
-  currentHLS   <- hlsSet
-
-  case (currentGHC, currentHLS) of
-    (Just gv, Just hv) | gv `notElem` supportedGHC -> do
-      logWarn $
-        "GHC " <> T.pack (prettyShow gv) <> " is not compatible with " <>
-        "Haskell Language Server " <> T.pack (prettyShow hv) <> "." <> "\n" <>
-        "Haskell IDE support may not work until this is fixed." <> "\n" <>
-        "Install a different HLS version, or install and set one of the following GHCs:" <> "\n" <>
-        T.pack (prettyShow supportedGHC)
-
-    _ -> return ()
-
-    ------------------
-    --[ List tools ]--
-    ------------------
-
-
--- | Filter data type for 'listVersions'.
-data ListCriteria = ListInstalled
-                  | ListSet
-                  | ListAvailable
-                  deriving Show
-
--- | A list result describes a single tool version
--- and various of its properties.
-data ListResult = ListResult
-  { lTool      :: Tool
-  , lVer       :: Version
-  , lCross     :: Maybe Text -- ^ currently only for GHC
-  , lTag       :: [Tag]
-  , lInstalled :: Bool
-  , lSet       :: Bool -- ^ currently active version
-  , fromSrc    :: Bool -- ^ compiled from source
-  , lStray     :: Bool -- ^ not in download info
-  , lNoBindist :: Bool -- ^ whether the version is available for this platform/arch
-  , hlsPowered :: Bool
-  }
-  deriving (Eq, Ord, Show)
-
-
--- | Extract all available tool versions and their tags.
-availableToolVersions :: GHCupDownloads -> Tool -> Map.Map Version VersionInfo
-availableToolVersions av tool = view
-  (at tool % non Map.empty)
-  av
-
-
--- | List all versions from the download info, as well as stray
--- versions.
-listVersions :: ( MonadCatch m
-                , HasLog env
-                , MonadThrow m
-                , HasLog env
-                , MonadIO m
-                , MonadReader env m
-                , HasDirs env
-                , HasPlatformReq env
-                , HasGHCupInfo env
-                )
-             => Maybe Tool
-             -> Maybe ListCriteria
-             -> m [ListResult]
-listVersions lt' criteria = do
-  -- some annoying work to avoid too much repeated IO
-  cSet <- cabalSet
-  cabals <- getInstalledCabals
-  hlsSet' <- hlsSet
-  hlses <- getInstalledHLSs
-  sSet <- stackSet
-  stacks <- getInstalledStacks
-
-  go lt' cSet cabals hlsSet' hlses sSet stacks
- where
-  go lt cSet cabals hlsSet' hlses sSet stacks = do
-    case lt of
-      Just t -> do
-        GHCupInfo { _ghcupDownloads = dls } <- getGHCupInfo
-        -- get versions from GHCupDownloads
-        let avTools = availableToolVersions dls t
-        lr <- filter' <$> forM (Map.toList avTools) (toListResult t cSet cabals hlsSet' hlses sSet stacks)
-
-        case t of
-          GHC -> do
-            slr <- strayGHCs avTools
-            pure (sort (slr ++ lr))
-          Cabal -> do
-            slr <- strayCabals avTools cSet cabals
-            pure (sort (slr ++ lr))
-          HLS -> do
-            slr <- strayHLS avTools hlsSet' hlses
-            pure (sort (slr ++ lr))
-          Stack -> do
-            slr <- strayStacks avTools sSet stacks
-            pure (sort (slr ++ lr))
-          GHCup -> do
-            let cg = maybeToList $ currentGHCup avTools
-            pure (sort (cg ++ lr))
-      Nothing -> do
-        ghcvers   <- go (Just GHC) cSet cabals hlsSet' hlses sSet stacks
-        cabalvers <- go (Just Cabal) cSet cabals hlsSet' hlses sSet stacks
-        hlsvers   <- go (Just HLS) cSet cabals hlsSet' hlses sSet stacks
-        ghcupvers <- go (Just GHCup) cSet cabals hlsSet' hlses sSet stacks
-        stackvers <- go (Just Stack) cSet cabals hlsSet' hlses sSet stacks
-        pure (ghcvers <> cabalvers <> hlsvers <> stackvers <> ghcupvers)
-  strayGHCs :: ( MonadCatch m
-               , MonadReader env m
-               , HasDirs env
-               , MonadThrow m
-               , HasLog env
-               , MonadIO m
-               )
-            => Map.Map Version VersionInfo
-            -> m [ListResult]
-  strayGHCs avTools = do
-    ghcs <- getInstalledGHCs
-    fmap catMaybes $ forM ghcs $ \case
-      Right tver@GHCTargetVersion{ _tvTarget = Nothing, .. } -> do
-        case Map.lookup _tvVersion avTools of
-          Just _  -> pure Nothing
-          Nothing -> do
-            lSet    <- fmap (maybe False (\(GHCTargetVersion _ v ) -> v == _tvVersion)) $ ghcSet Nothing
-            fromSrc <- ghcSrcInstalled tver
-            hlsPowered <- fmap (elem _tvVersion) hlsGHCVersions
-            pure $ Just $ ListResult
-              { lTool      = GHC
-              , lVer       = _tvVersion
-              , lCross     = Nothing
-              , lTag       = []
-              , lInstalled = True
-              , lStray     = isNothing (Map.lookup _tvVersion avTools)
-              , lNoBindist = False
-              , ..
-              }
-      Right tver@GHCTargetVersion{ .. } -> do
-        lSet    <- fmap (maybe False (\(GHCTargetVersion _ v ) -> v == _tvVersion)) $ ghcSet _tvTarget
-        fromSrc <- ghcSrcInstalled tver
-        hlsPowered <- fmap (elem _tvVersion) hlsGHCVersions
-        pure $ Just $ ListResult
-          { lTool      = GHC
-          , lVer       = _tvVersion
-          , lCross     = _tvTarget
-          , lTag       = []
-          , lInstalled = True
-          , lStray     = True -- NOTE: cross currently cannot be installed via bindist
-          , lNoBindist = False
-          , ..
-          }
-      Left e -> do
-        logWarn
-          $ "Could not parse version of stray directory" <> T.pack e
-        pure Nothing
-
-  strayCabals :: ( MonadReader env m
-                 , HasDirs env
-                 , MonadCatch m
-                 , MonadThrow m
-                 , HasLog env
-                 , MonadIO m
-                 )
-            => Map.Map Version VersionInfo
-            -> Maybe Version
-            -> [Either FilePath Version]
-            -> m [ListResult]
-  strayCabals avTools cSet cabals = do
-    fmap catMaybes $ forM cabals $ \case
-      Right ver ->
-        case Map.lookup ver avTools of
-          Just _  -> pure Nothing
-          Nothing -> do
-            let lSet = cSet == Just ver
-            pure $ Just $ ListResult
-              { lTool      = Cabal
-              , lVer       = ver
-              , lCross     = Nothing
-              , lTag       = []
-              , lInstalled = True
-              , lStray     = isNothing (Map.lookup ver avTools)
-              , lNoBindist = False
-              , fromSrc    = False -- actually, we don't know :>
-              , hlsPowered = False
-              , ..
-              }
-      Left e -> do
-        logWarn
-          $ "Could not parse version of stray directory" <> T.pack e
-        pure Nothing
-
-  strayHLS :: ( MonadReader env m
-              , HasDirs env
-              , MonadCatch m
-              , MonadThrow m
-              , HasLog env
-              , MonadIO m)
-           => Map.Map Version VersionInfo
-           -> Maybe Version
-           -> [Either FilePath Version]
-           -> m [ListResult]
-  strayHLS avTools hlsSet' hlss = do
-    fmap catMaybes $ forM hlss $ \case
-      Right ver ->
-        case Map.lookup ver avTools of
-          Just _  -> pure Nothing
-          Nothing -> do
-            let lSet = hlsSet' == Just ver
-            pure $ Just $ ListResult
-              { lTool      = HLS
-              , lVer       = ver
-              , lCross     = Nothing
-              , lTag       = []
-              , lInstalled = True
-              , lStray     = isNothing (Map.lookup ver avTools)
-              , lNoBindist = False
-              , fromSrc    = False -- actually, we don't know :>
-              , hlsPowered = False
-              , ..
-              }
-      Left e -> do
-        logWarn
-          $ "Could not parse version of stray directory" <> T.pack e
-        pure Nothing
-
-  strayStacks :: ( MonadReader env m
-                 , HasDirs env
-                 , MonadCatch m
-                 , MonadThrow m
-                 , HasLog env
-                 , MonadIO m
-                 )
-              => Map.Map Version VersionInfo
-              -> Maybe Version
-              -> [Either FilePath Version]
-              -> m [ListResult]
-  strayStacks avTools stackSet' stacks = do
-    fmap catMaybes $ forM stacks $ \case
-      Right ver ->
-        case Map.lookup ver avTools of
-          Just _  -> pure Nothing
-          Nothing -> do
-            let lSet = stackSet' == Just ver
-            pure $ Just $ ListResult
-              { lTool      = Stack
-              , lVer       = ver
-              , lCross     = Nothing
-              , lTag       = []
-              , lInstalled = True
-              , lStray     = isNothing (Map.lookup ver avTools)
-              , lNoBindist = False
-              , fromSrc    = False -- actually, we don't know :>
-              , hlsPowered = False
-              , ..
-              }
-      Left e -> do
-        logWarn
-          $ "Could not parse version of stray directory" <> T.pack e
-        pure Nothing
-
-  currentGHCup :: Map.Map Version VersionInfo -> Maybe ListResult
-  currentGHCup av =
-    let currentVer = fromJust $ pvpToVersion ghcUpVer ""
-        listVer    = Map.lookup currentVer av
-        latestVer  = fst <$> headOf (getTagged Latest) av
-        recommendedVer = fst <$> headOf (getTagged Latest) av
-        isOld  = maybe True (> currentVer) latestVer && maybe True (> currentVer) recommendedVer
-    in if | Map.member currentVer av -> Nothing
-          | otherwise -> Just $ ListResult { lVer    = currentVer
-                                           , lTag    = maybe (if isOld then [Old] else []) _viTags listVer
-                                           , lCross  = Nothing
-                                           , lTool   = GHCup
-                                           , fromSrc = False
-                                           , lStray  = isNothing listVer
-                                           , lSet    = True
-                                           , lInstalled = True
-                                           , lNoBindist = False
-                                           , hlsPowered = False
-                                           }
-
-  -- NOTE: this are not cross ones, because no bindists
-  toListResult :: ( HasLog env
-                  , MonadReader env m
-                  , HasDirs env
-                  , HasGHCupInfo env
-                  , HasPlatformReq env
-                  , MonadIO m
-                  , MonadCatch m
-                  )
-               => Tool
-               -> Maybe Version
-               -> [Either FilePath Version]
-               -> Maybe Version
-               -> [Either FilePath Version]
-               -> Maybe Version
-               -> [Either FilePath Version]
-               -> (Version, VersionInfo)
-               -> m ListResult
-  toListResult t cSet cabals hlsSet' hlses stackSet' stacks (v, _viTags -> tags) = do
-    case t of
-      GHC -> do
-        lNoBindist <- fmap (isLeft . veitherToEither) $ runE @'[NoDownload] $ getDownloadInfo GHC v
-        let tver = mkTVer v
-        lSet       <- fmap (maybe False (\(GHCTargetVersion _ v') -> v' == v)) $ ghcSet Nothing
-        lInstalled <- ghcInstalled tver
-        fromSrc    <- ghcSrcInstalled tver
-        hlsPowered <- fmap (elem v) hlsGHCVersions
-        pure ListResult { lVer = v, lCross = Nothing , lTag = tags, lTool = t, lStray = False, .. }
-      Cabal -> do
-        lNoBindist <- fmap (isLeft . veitherToEither) $ runE @'[NoDownload] $ getDownloadInfo Cabal v
-        let lSet = cSet == Just v
-        let lInstalled = elem v $ rights cabals
-        pure ListResult { lVer    = v
-                        , lCross  = Nothing
-                        , lTag    = tags
-                        , lTool   = t
-                        , fromSrc = False
-                        , lStray  = False
-                        , hlsPowered = False
-                        , ..
-                        }
-      GHCup -> do
-        let lSet       = prettyPVP ghcUpVer == prettyVer v
-        let lInstalled = lSet
-        pure ListResult { lVer    = v
-                        , lTag    = tags
-                        , lCross  = Nothing
-                        , lTool   = t
-                        , fromSrc = False
-                        , lStray  = False
-                        , lNoBindist = False
-                        , hlsPowered = False
-                        , ..
-                        }
-      HLS -> do
-        lNoBindist <- fmap (isLeft . veitherToEither) $ runE @'[NoDownload] $ getDownloadInfo HLS v
-        let lSet = hlsSet' == Just v
-        let lInstalled = elem v $ rights hlses
-        pure ListResult { lVer    = v
-                        , lCross  = Nothing
-                        , lTag    = tags
-                        , lTool   = t
-                        , fromSrc = False
-                        , lStray  = False
-                        , hlsPowered = False
-                        , ..
-                        }
-      Stack -> do
-        lNoBindist <- fmap (isLeft . veitherToEither) $ runE @'[NoDownload] $ getDownloadInfo Stack v
-        let lSet = stackSet' == Just v
-        let lInstalled = elem v $ rights stacks
-        pure ListResult { lVer    = v
-                        , lCross  = Nothing
-                        , lTag    = tags
-                        , lTool   = t
-                        , fromSrc = False
-                        , lStray  = False
-                        , hlsPowered = False
-                        , ..
-                        }
-
-
-  filter' :: [ListResult] -> [ListResult]
-  filter' lr = case criteria of
-    Nothing            -> lr
-    Just ListInstalled -> filter (\ListResult {..} -> lInstalled) lr
-    Just ListSet       -> filter (\ListResult {..} -> lSet) lr
-    Just ListAvailable -> filter (\ListResult {..} -> not lNoBindist) lr
-
-
-
-    --------------------
-    --[ GHC/cabal rm ]--
-    --------------------
-
-
--- | Delete a ghc version and all its symlinks.
---
--- This may leave GHCup without a "set" version.
--- Will try to fix the ghc-x.y symlink after removal (e.g. to an
--- older version).
-rmGHCVer :: ( MonadReader env m
-            , HasDirs env
-            , MonadThrow m
-            , HasLog env
-            , MonadIO m
-            , MonadFail m
-            , MonadCatch m
-            , MonadMask m
-            , MonadUnliftIO m
-            )
-         => GHCTargetVersion
-         -> Excepts '[NotInstalled] m ()
-rmGHCVer ver = do
-  isSetGHC <- lift $ fmap (== Just ver) $ ghcSet (_tvTarget ver)
-
-  whenM (lift $ fmap not $ ghcInstalled ver) (throwE (NotInstalled GHC ver))
-  dir <- lift $ ghcupGHCDir ver
-
-  -- this isn't atomic, order matters
-  when isSetGHC $ do
-    lift $ logInfo "Removing ghc symlinks"
-    liftE $ rmPlainGHC (_tvTarget ver)
-
-  lift $ logInfo "Removing ghc-x.y.z symlinks"
-  liftE $ rmMinorGHCSymlinks ver
-
-  lift $ logInfo "Removing/rewiring ghc-x.y symlinks"
-  -- first remove
-  handle (\(_ :: ParseError) -> pure ()) $ liftE $ rmMajorGHCSymlinks ver
-  -- then fix them (e.g. with an earlier version)
-
-  lift $ logInfo $ "Removing directory recursively: " <> T.pack dir
-  lift $ recyclePathForcibly dir
-
-  v' <-
-    handle
-      (\(e :: ParseError) -> lift $ logWarn (T.pack $ displayException e) >> pure Nothing)
-    $ fmap Just
-    $ getMajorMinorV (_tvVersion ver)
-  forM_ v' $ \(mj, mi) -> lift (getGHCForPVP (PVP (fromIntegral mj :| [fromIntegral mi])) (_tvTarget ver))
-    >>= mapM_ (\v -> liftE $ setGHC v SetGHC_XY Nothing)
-
-  Dirs {..} <- lift getDirs
-
-  lift $ hideError doesNotExistErrorType $ rmDirectoryLink (baseDir </> "share")
-
-
--- | Delete a cabal version. Will try to fix the @cabal@ symlink
--- after removal (e.g. setting it to an older version).
-rmCabalVer :: ( MonadMask m
-              , MonadReader env m
-              , HasDirs env
-              , MonadThrow m
-              , HasLog env
-              , MonadIO m
-              , MonadFail m
-              , MonadCatch m
-              , MonadUnliftIO m
-              )
-           => Version
-           -> Excepts '[NotInstalled] m ()
-rmCabalVer ver = do
-  whenM (lift $ fmap not $ cabalInstalled ver) $ throwE (NotInstalled Cabal (GHCTargetVersion Nothing ver))
-
-  cSet      <- lift cabalSet
-
-  Dirs {..} <- lift getDirs
-
-  let cabalFile = "cabal-" <> T.unpack (prettyVer ver) <> exeExt
-  lift $ hideError doesNotExistErrorType $ recycleFile (binDir </> cabalFile)
-
-  when (Just ver == cSet) $ do
-    cVers <- lift $ fmap rights getInstalledCabals
-    case headMay . reverse . sort $ cVers of
-      Just latestver -> setCabal latestver
-      Nothing        -> lift $ rmLink (binDir </> "cabal" <> exeExt)
-
-
--- | Delete a hls version. Will try to fix the hls symlinks
--- after removal (e.g. setting it to an older version).
-rmHLSVer :: ( MonadMask m
-            , MonadReader env m
-            , HasDirs env
-            , MonadThrow m
-            , HasLog env
-            , MonadIO m
-            , MonadFail m
-            , MonadCatch m
-            , MonadUnliftIO m
-            )
-         => Version
-         -> Excepts '[NotInstalled] m ()
-rmHLSVer ver = do
-  whenM (lift $ fmap not $ hlsInstalled ver) $ throwE (NotInstalled HLS (GHCTargetVersion Nothing ver))
-
-  isHlsSet <- lift hlsSet
-
-  liftE $ rmMinorHLSSymlinks ver
-  hlsDir <- ghcupHLSDir ver
-  recyclePathForcibly hlsDir
-
-  when (Just ver == isHlsSet) $ do
-    -- delete all set symlinks
-    rmPlainHLS
-    -- set latest hls
-    hlsVers <- lift $ fmap rights getInstalledHLSs
-    case headMay . reverse . sort $ hlsVers of
-      Just latestver -> setHLS latestver SetHLSOnly Nothing
-      Nothing        -> pure ()
-
-
--- | Delete a stack version. Will try to fix the @stack@ symlink
--- after removal (e.g. setting it to an older version).
-rmStackVer :: ( MonadMask m
-              , MonadReader env m
-              , HasDirs env
-              , MonadThrow m
-              , HasLog env
-              , MonadIO m
-              , MonadFail m
-              , MonadCatch m
-              , MonadUnliftIO m
-              )
-           => Version
-           -> Excepts '[NotInstalled] m ()
-rmStackVer ver = do
-  whenM (lift $ fmap not $ stackInstalled ver) $ throwE (NotInstalled Stack (GHCTargetVersion Nothing ver))
-
-  sSet      <- lift stackSet
-
-  Dirs {..} <- lift getDirs
-
-  let stackFile = "stack-" <> T.unpack (prettyVer ver) <> exeExt
-  lift $ hideError doesNotExistErrorType $ recycleFile (binDir </> stackFile)
-
-  when (Just ver == sSet) $ do
-    sVers <- lift $ fmap rights getInstalledStacks
-    case headMay . reverse . sort $ sVers of
-      Just latestver -> setStack latestver
-      Nothing        -> lift $ rmLink (binDir </> "stack" <> exeExt)
-
-
--- assuming the current scheme of having just 1 ghcup bin, no version info is required.
-rmGhcup :: ( MonadReader env m
-           , HasDirs env
-           , MonadIO m
-           , MonadCatch m
-           , HasLog env
-           , MonadMask m
-           , MonadUnliftIO m
-           )
-        => m ()
-rmGhcup = do
-  Dirs { .. } <- getDirs
-  let ghcupFilename = "ghcup" <> exeExt
-  let ghcupFilepath = binDir </> ghcupFilename
-
-  currentRunningExecPath <- liftIO getExecutablePath
-
-  -- if paths do no exist, warn user, and continue to compare them, as is,
-  -- which should eventually fail and result in a non-standard install warning
-
-  p1 <- handleIO' doesNotExistErrorType
-                  (handlePathNotPresent currentRunningExecPath)
-                  (liftIO $ canonicalizePath currentRunningExecPath)
-
-  p2 <- handleIO' doesNotExistErrorType
-                  (handlePathNotPresent ghcupFilepath)
-                  (liftIO $ canonicalizePath ghcupFilepath)
-
-  let areEqualPaths = equalFilePath p1 p2
-
-  unless areEqualPaths $ logWarn $ nonStandardInstallLocationMsg currentRunningExecPath
-
-  if isWindows
-  then do
-    -- since it doesn't seem possible to delete a running exe on windows
-    -- we move it to temp dir, to be deleted at next reboot
-    tempFilepath <- mkGhcupTmpDir
-    hideError UnsupportedOperation $
-              liftIO $ hideError NoSuchThing $
-              moveFile ghcupFilepath (tempFilepath </> "ghcup")
-  else
-    -- delete it.
-    hideError doesNotExistErrorType $ rmFile ghcupFilepath
-
-  where
-    handlePathNotPresent fp _err = do
-      logDebug $ "Error: The path does not exist, " <> T.pack fp
-      pure fp
-
-    nonStandardInstallLocationMsg path = T.pack $
-      "current ghcup is invoked from a non-standard location: \n"
-      <> path <>
-      "\n you may have to uninstall it manually."
-
-rmTool :: ( MonadReader env m
-          , HasDirs env
-          , HasLog env
-          , MonadFail m
-          , MonadMask m
-          , MonadUnliftIO m)
-          => ListResult
-          -> Excepts '[NotInstalled ] m ()
-rmTool ListResult {lVer, lTool, lCross} = do
-  case lTool of
-    GHC ->
-      let ghcTargetVersion = GHCTargetVersion lCross lVer
-      in rmGHCVer ghcTargetVersion
-    HLS -> rmHLSVer lVer
-    Cabal -> rmCabalVer lVer
-    Stack -> rmStackVer lVer
-    GHCup -> lift rmGhcup
-
-
-rmGhcupDirs :: ( MonadReader env m
-               , HasDirs env
-               , MonadIO m
-               , HasLog env
-               , MonadCatch m
-               , MonadMask m )
-            => m [FilePath]
-rmGhcupDirs = do
-  Dirs
-    { baseDir
-    , binDir
-    , logsDir
-    , cacheDir
-    , recycleDir
-    } <- getDirs
-
-  let envFilePath = baseDir </> "env"
-
-  confFilePath <- getConfigFilePath
-
-  handleRm $ rmEnvFile  envFilePath
-  handleRm $ rmConfFile confFilePath
-
-  -- for xdg dirs, the order matters here
-  handleRm $ rmDir logsDir
-  handleRm $ rmDir cacheDir
-
-  handleRm $ rmBinDir binDir
-  handleRm $ rmDir recycleDir
-  when isWindows $ do
-    logInfo $ "removing " <> T.pack (baseDir </> "msys64")
-    handleRm $ rmPathForcibly (baseDir </> "msys64")
-
-  handleRm $ removeEmptyDirsRecursive baseDir
-
-  -- report files in baseDir that are left-over after
-  -- the standard location deletions above
-  hideErrorDef [doesNotExistErrorType] [] $ reportRemainingFiles baseDir
-
-  where
-    handleRm :: (MonadReader env m, MonadCatch m, HasLog env, MonadIO m)  => m () -> m ()
-    handleRm = handleIO (\e -> logDebug $ "Part of the cleanup action failed with error: " <> T.pack (displayException e) <> "\n"
-                                <> "continuing regardless...")
-
-    rmEnvFile :: (HasLog env, MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
-    rmEnvFile enFilePath = do
-      logInfo "Removing Ghcup Environment File"
-      hideErrorDef [permissionErrorType] () $ deleteFile enFilePath
-
-    rmConfFile :: (HasLog env, MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
-    rmConfFile confFilePath = do
-      logInfo "removing Ghcup Config File"
-      hideErrorDef [permissionErrorType] () $ deleteFile confFilePath
-
-    rmDir :: (HasLog env, MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
-    rmDir dir =
-      -- 'getDirectoryContentsRecursive' is lazy IO. In case
-      -- an error leaks through, we catch it here as well,
-      -- althought 'deleteFile' should already handle it.
-      hideErrorDef [doesNotExistErrorType] () $ do
-        logInfo $ "removing " <> T.pack dir
-        contents <- liftIO $ getDirectoryContentsRecursive dir
-        forM_ contents (deleteFile . (dir </>))
-
-    rmBinDir :: (MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
-    rmBinDir binDir
-      | isWindows = removeDirIfEmptyOrIsSymlink binDir
-      | otherwise = do
-          isXDGStyle <- liftIO useXDG
-          if not isXDGStyle
-            then removeDirIfEmptyOrIsSymlink binDir
-            else pure ()
-
-    reportRemainingFiles :: MonadIO m => FilePath -> m [FilePath]
-    reportRemainingFiles dir = do
-      -- force the files so the errors don't leak
-      (force -> !remainingFiles) <- liftIO
-        (getDirectoryContentsRecursive dir >>= evaluate)
-      let normalizedFilePaths = fmap normalise remainingFiles
-      let sortedByDepthRemainingFiles = sortBy (flip compareFn) normalizedFilePaths
-      let remainingFilesAbsolute = fmap (dir </>) sortedByDepthRemainingFiles
-
-      pure remainingFilesAbsolute
-
-      where
-        calcDepth :: FilePath -> Int
-        calcDepth = length . filter isPathSeparator
-
-        compareFn :: FilePath -> FilePath -> Ordering
-        compareFn fp1 fp2 = compare (calcDepth fp1) (calcDepth fp2)
-
-    removeEmptyDirsRecursive :: (MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
-    removeEmptyDirsRecursive fp = do
-      cs <- liftIO $ listDirectory fp >>= filterM doesDirectoryExist . fmap (fp </>)
-      forM_ cs removeEmptyDirsRecursive
-      hideError InappropriateType $ removeDirIfEmptyOrIsSymlink fp
-
-
-    -- we expect only files inside cache/log dir
-    -- we report remaining files/dirs later,
-    -- hence the force/quiet mode in these delete functions below.
-
-    deleteFile :: (MonadReader env m, HasDirs env, MonadMask m, MonadIO m) => FilePath -> m ()
-    deleteFile filepath = do
-      hideError doesNotExistErrorType
-        $ hideError InappropriateType $ rmFile filepath
-
-    removeDirIfEmptyOrIsSymlink :: (MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
-    removeDirIfEmptyOrIsSymlink filepath =
-      hideError UnsatisfiedConstraints $
-      handleIO' InappropriateType
-            (handleIfSym filepath)
-            (liftIO $ rmDirectory filepath)
-      where
-        handleIfSym fp e = do
-          isSym <- liftIO $ pathIsSymbolicLink fp
-          if isSym
-          then deleteFile fp
-          else liftIO $ ioError e
-
-
-
-    ------------------
-    --[ Debug info ]--
-    ------------------
-
-
-getDebugInfo :: ( Alternative m
-                , MonadFail m
-                , MonadReader env m
-                , HasDirs env
-                , HasLog env
-                , MonadCatch m
-                , MonadIO m
-                )
-             => Excepts
-                  '[NoCompatiblePlatform , NoCompatibleArch , DistroNotFound]
-                  m
-                  DebugInfo
-getDebugInfo = do
-  Dirs {..} <- lift getDirs
-  let diBaseDir  = baseDir
-  let diBinDir   = binDir
-  diGHCDir       <- lift ghcupGHCBaseDir
-  let diCacheDir = cacheDir
-  diArch         <- lE getArchitecture
-  diPlatform     <- liftE getPlatform
-  pure $ DebugInfo { .. }
-
-
-
-
-    ---------------
-    --[ Compile ]--
-    ---------------
-
-
--- | Compile a GHC from source. This behaves wrt symlinks and installation
--- the same as 'installGHCBin'.
-compileGHC :: ( MonadMask m
-              , MonadReader env m
-              , HasDirs env
-              , HasPlatformReq env
-              , HasGHCupInfo env
-              , HasSettings env
-              , MonadThrow m
-              , MonadResource m
-              , HasLog env
-              , MonadIO m
-              , MonadUnliftIO m
-              , MonadFail m
-              )
-           => Either GHCTargetVersion GitBranch          -- ^ version to install
-           -> Maybe Version            -- ^ overwrite version
-           -> Either Version FilePath  -- ^ version to bootstrap with
-           -> Maybe Int                -- ^ jobs
-           -> Maybe FilePath           -- ^ build config
-           -> Maybe (Either FilePath [URI])  -- ^ patches
-           -> [Text]                   -- ^ additional args to ./configure
-           -> Maybe String             -- ^ build flavour
-           -> Bool
-           -> InstallDir
-           -> Excepts
-                '[ AlreadyInstalled
-                 , BuildFailed
-                 , DigestError
-                 , GPGError
-                 , DownloadFailed
-                 , GHCupSetError
-                 , NoDownload
-                 , NotFoundInPATH
-                 , PatchFailed
-                 , UnknownArchive
-                 , TarDirDoesNotExist
-                 , NotInstalled
-                 , DirNotEmpty
-                 , ArchiveResult
-                 , FileDoesNotExistError
-                 , HadrianNotFound
-                 , InvalidBuildConfig
-                 , ProcessError
-                 , CopyError
-                 , BuildFailed
-                 ]
-                m
-                GHCTargetVersion
-compileGHC targetGhc ov bstrap jobs mbuildConfig patches aargs buildFlavour hadrian installDir
-  = do
-    PlatformRequest { .. } <- lift getPlatformReq
-    GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
-
-    (workdir, tmpUnpack, tver) <- case targetGhc of
-      -- unpack from version tarball
-      Left tver -> do
-        lift $ logDebug $ "Requested to compile: " <> tVerToText tver <> " with " <> either prettyVer T.pack bstrap
-
-        -- download source tarball
-        dlInfo <-
-          preview (ix GHC % ix (tver ^. tvVersion) % viSourceDL % _Just) dls
-            ?? NoDownload
-        dl <- liftE $ downloadCached dlInfo Nothing
-
-        -- unpack
-        tmpUnpack <- lift mkGhcupTmpDir
-        liftE $ cleanUpOnError tmpUnpack (unpackToDir tmpUnpack dl)
-        liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform tmpUnpack
-
-        workdir <- maybe (pure tmpUnpack)
-                         (liftE . intoSubdir tmpUnpack)
-                         (view dlSubdir dlInfo)
-        liftE $ applyAnyPatch patches workdir
-
-        pure (workdir, tmpUnpack, tver)
-
-      -- clone from git
-      Right GitBranch{..} -> do
-        tmpUnpack <- lift mkGhcupTmpDir
-        let git args = execLogged "git" ("--no-pager":args) (Just tmpUnpack) "git" Nothing
-        tver <- reThrowAll @_ @'[PatchFailed, ProcessError, NotFoundInPATH, DigestError, DownloadFailed, GPGError] DownloadFailed $ do
-          let rep = fromMaybe "https://gitlab.haskell.org/ghc/ghc.git" repo
-          lift $ logInfo $ "Fetching git repo " <> T.pack rep <> " at ref " <> T.pack ref <> " (this may take a while)"
-          lEM $ git [ "init" ]
-          lEM $ git [ "remote"
-                    , "add"
-                    , "origin"
-                    , fromString rep ]
-
-          let fetch_args =
-                    [ "fetch"
-                    , "--depth"
-                    , "1"
-                    , "--quiet"
-                    , "origin"
-                    , fromString ref ]
-          lEM $ git fetch_args
-
-          lEM $ git [ "checkout", "FETCH_HEAD" ]
-          lEM $ git [ "submodule", "update", "--init", "--depth", "1" ]
-          liftE $ applyAnyPatch patches tmpUnpack
-          lEM $ execWithGhcEnv "python3" ["./boot"] (Just tmpUnpack) "ghc-bootstrap"
-          lEM $ execWithGhcEnv "sh" ["./configure"] (Just tmpUnpack) "ghc-bootstrap"
-          CapturedProcess {..} <- lift $ makeOut
-            ["show!", "--quiet", "VALUE=ProjectVersion" ] (Just tmpUnpack)
-          case _exitCode of
-            ExitSuccess -> throwEither . MP.parse ghcProjectVersion "" . decUTF8Safe' $ _stdOut
-            ExitFailure c -> fail ("Could not figure out GHC project version. Exit code was: " <> show c <> ". Error was: " <> T.unpack (decUTF8Safe' _stdErr))
-
-        liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform tmpUnpack
-        lift $ logInfo $ "Git version " <> T.pack ref <> " corresponds to GHC version " <> prettyVer tver
-
-        pure (tmpUnpack, tmpUnpack, GHCTargetVersion Nothing tver)
-    -- the version that's installed may differ from the
-    -- compiled version, so the user can overwrite it
-    let installVer = maybe tver (\ov' -> tver { _tvVersion = ov' }) ov
-
-    alreadyInstalled <- lift $ ghcInstalled installVer
-    alreadySet <- fmap (== Just installVer) $ lift $ ghcSet (_tvTarget installVer)
-
-    when alreadyInstalled $ do
-      case installDir of
-        IsolateDir isoDir ->
-          lift $ logWarn $ "GHC " <> T.pack (prettyShow installVer) <> " already installed. Isolate installing to " <> T.pack isoDir
-        GHCupInternal ->
-          lift $ logWarn $ "GHC " <> T.pack (prettyShow installVer) <> " already installed. Will overwrite existing version."
-      lift $ logWarn
-        "...waiting for 10 seconds before continuing, you can still abort..."
-      liftIO $ threadDelay 10000000 -- give the user a sec to intervene
-
-    ghcdir <- case installDir of
-      IsolateDir isoDir -> pure $ IsolateDirResolved isoDir
-      GHCupInternal -> GHCupDir <$> lift (ghcupGHCDir installVer)
-
-    (mBindist, bmk) <- liftE $ runBuildAction
-      tmpUnpack
-      Nothing
-      (do
-        b <- if hadrian
-             then compileHadrianBindist tver workdir ghcdir
-             else compileMakeBindist tver workdir ghcdir
-        bmk <- liftIO $ handleIO (\_ -> pure "") $ B.readFile (build_mk workdir)
-        pure (b, bmk)
-      )
-
-    case installDir of
-      GHCupInternal ->
-        -- only remove old ghc in regular installs
-        when alreadyInstalled $ do
-          lift $ logInfo "Deleting existing installation"
-          liftE $ rmGHCVer installVer
-
-      _ -> pure ()
-
-    forM_ mBindist $ \bindist -> do
-      liftE $ installPackedGHC bindist
-                               (Just $ RegexDir "ghc-.*")
-                               ghcdir
-                               (installVer ^. tvVersion)
-                               False       -- not a force install, since we already overwrite when compiling.
-
-    liftIO $ B.writeFile (fromInstallDir ghcdir </> ghcUpSrcBuiltFile) bmk
-
-    case installDir of
-      -- set and make symlinks for regular (non-isolated) installs
-      GHCupInternal -> do
-        reThrowAll GHCupSetError $ postGHCInstall installVer
-        -- restore
-        when alreadySet $ liftE $ void $ setGHC installVer SetGHCOnly Nothing
-
-      _ -> pure ()
-
-    pure installVer
-
- where
-  defaultConf =
-    let cross_mk = $(LitE . StringL <$> (qAddDependentFile "data/build_mk/cross" >> runIO (readFile "data/build_mk/cross")))
-        default_mk = $(LitE . StringL <$> (qAddDependentFile "data/build_mk/default" >> runIO (readFile "data/build_mk/default")))
-    in case targetGhc of
-         Left (GHCTargetVersion (Just _) _) -> cross_mk
-         _ -> default_mk
-
-  compileHadrianBindist :: ( MonadReader env m
-                           , HasDirs env
-                           , HasSettings env
-                           , HasPlatformReq env
-                           , MonadThrow m
-                           , MonadCatch m
-                           , HasLog env
-                           , MonadIO m
-                           , MonadFail m
-                           )
-                        => GHCTargetVersion
-                        -> FilePath
-                        -> InstallDirResolved
-                        -> Excepts
-                             '[ FileDoesNotExistError
-                              , HadrianNotFound
-                              , InvalidBuildConfig
-                              , PatchFailed
-                              , ProcessError
-                              , NotFoundInPATH
-                              , CopyError]
-                             m
-                             (Maybe FilePath)  -- ^ output path of bindist, None for cross
-  compileHadrianBindist tver workdir ghcdir = do
-    lEM $ execWithGhcEnv "python3" ["./boot"] (Just workdir) "ghc-bootstrap"
-
-    liftE $ configureBindist tver workdir ghcdir
-
-    lift $ logInfo "Building (this may take a while)..."
-    hadrian_build <- liftE $ findHadrianFile workdir
-    lEM $ execWithGhcEnv hadrian_build
-                          ( maybe [] (\j  -> ["-j" <> show j]         ) jobs
-                         ++ maybe [] (\bf -> ["--flavour=" <> bf]) buildFlavour
-                         ++ ["binary-dist"]
-                          )
-                          (Just workdir) "ghc-make"
-    [tar] <- liftIO $ findFiles
-      (workdir </> "_build" </> "bindist")
-      (makeRegexOpts compExtended
-                     execBlank
-                     ([s|^ghc-.*\.tar\..*$|] :: ByteString)
-      )
-    liftE $ fmap Just $ copyBindist tver tar (workdir </> "_build" </> "bindist")
-
-  findHadrianFile :: (MonadIO m)
-                  => FilePath
-                  -> Excepts
-                       '[HadrianNotFound]
-                       m
-                       FilePath
-  findHadrianFile workdir = do
-    let possible_files = if isWindows
-                         then ((workdir </> "hadrian") </>) <$> ["build.bat"]
-                         else ((workdir </> "hadrian") </>) <$> ["build", "build.sh"]
-    exsists <- forM possible_files (\f -> liftIO (doesFileExist f) <&> (,f))
-    case filter fst exsists of
-      [] -> throwE HadrianNotFound
-      ((_, x):_) -> pure x
-
-  compileMakeBindist :: ( MonadReader env m
-                        , HasDirs env
-                        , HasSettings env
-                        , HasPlatformReq env
-                        , MonadThrow m
-                        , MonadCatch m
-                        , HasLog env
-                        , MonadIO m
-                        , MonadFail m
-                        )
-                     => GHCTargetVersion
-                     -> FilePath
-                     -> InstallDirResolved
-                     -> Excepts
-                          '[ FileDoesNotExistError
-                           , HadrianNotFound
-                           , InvalidBuildConfig
-                           , PatchFailed
-                           , ProcessError
-                           , NotFoundInPATH
-                           , CopyError]
-                          m
-                       (Maybe FilePath)  -- ^ output path of bindist, None for cross
-  compileMakeBindist tver workdir ghcdir = do
-    liftE $ configureBindist tver workdir ghcdir
-
-    case mbuildConfig of
-      Just bc -> liftIOException
-        doesNotExistErrorType
-        (FileDoesNotExistError bc)
-        (liftIO $ copyFile bc (build_mk workdir))
-      Nothing ->
-        liftIO $ T.writeFile (build_mk workdir) (addBuildFlavourToConf defaultConf)
-
-    liftE $ checkBuildConfig (build_mk workdir)
-
-    lift $ logInfo "Building (this may take a while)..."
-    lEM $ make (maybe [] (\j -> ["-j" <> fS (show j)]) jobs) (Just workdir)
-
-    if | isCross tver -> do
-          lift $ logInfo "Installing cross toolchain..."
-          lEM $ make ["install"] (Just workdir)
-          pure Nothing
-       | otherwise -> do
-          lift $ logInfo "Creating bindist..."
-          lEM $ make ["binary-dist"] (Just workdir)
-          [tar] <- liftIO $ findFiles
-            workdir
-            (makeRegexOpts compExtended
-                           execBlank
-                           ([s|^ghc-.*\.tar\..*$|] :: ByteString)
-            )
-          liftE $ fmap Just $ copyBindist tver tar workdir
-
-  build_mk workdir = workdir </> "mk" </> "build.mk"
-
-  copyBindist :: ( MonadReader env m
-                 , HasDirs env
-                 , HasSettings env
-                 , HasPlatformReq env
-                 , MonadIO m
-                 , MonadThrow m
-                 , MonadCatch m
-                 , HasLog env
-                 )
-              => GHCTargetVersion
-              -> FilePath           -- ^ tar file
-              -> FilePath           -- ^ workdir
-              -> Excepts
-                   '[CopyError]
-                   m
-                   FilePath
-  copyBindist tver tar workdir = do
-    Dirs {..} <- lift getDirs
-    pfreq <- lift getPlatformReq
-    c       <- liftIO $ BL.readFile (workdir </> tar)
-    cDigest <-
-      fmap (T.take 8)
-      . lift
-      . throwEither
-      . E.decodeUtf8'
-      . B16.encode
-      . SHA256.hashlazy
-      $ c
-    cTime <- liftIO getCurrentTime
-    let tarName = makeValid ("ghc-"
-                            <> T.unpack (tVerToText tver)
-                            <> "-"
-                            <> pfReqToString pfreq
-                            <> "-"
-                            <> iso8601Show cTime
-                            <> "-"
-                            <> T.unpack cDigest
-                            <> ".tar"
-                            <> takeExtension tar)
-    let tarPath = cacheDir </> tarName
-    copyFileE (workdir </> tar)
-                                                             tarPath
-    lift $ logInfo $ "Copied bindist to " <> T.pack tarPath
-    pure tarPath
-
-  checkBuildConfig :: (MonadReader env m, MonadCatch m, MonadIO m, HasLog env)
-                   => FilePath
-                   -> Excepts
-                        '[FileDoesNotExistError, InvalidBuildConfig]
-                        m
-                        ()
-  checkBuildConfig bc = do
-    c <- liftIOException
-           doesNotExistErrorType
-           (FileDoesNotExistError bc)
-           (liftIO $ B.readFile bc)
-    let lines' = fmap T.strip . T.lines $ decUTF8Safe c
-
-   -- for cross, we need Stage1Only
-    case targetGhc of
-      Left (GHCTargetVersion (Just _) _) -> when ("Stage1Only = YES" `notElem` lines') $ throwE
-        (InvalidBuildConfig
-          [s|Cross compiling needs to be a Stage1 build, add "Stage1Only = YES" to your config!|]
-        )
-      _ -> pure ()
-
-    forM_ buildFlavour $ \bf ->
-      when (T.pack ("BuildFlavour = " <> bf) `notElem` lines') $ do
-        lift $ logWarn $ "Customly specified build config overwrites --flavour=" <> T.pack bf <> " switch! Waiting 5 seconds..."
-        liftIO $ threadDelay 5000000
-
-  addBuildFlavourToConf bc = case buildFlavour of
-    Just bf -> "BuildFlavour = " <> T.pack bf <> "\n" <> bc
-    Nothing -> bc
-
-  isCross :: GHCTargetVersion -> Bool
-  isCross = isJust . _tvTarget
-
-
-  configureBindist :: ( MonadReader env m
-                      , HasDirs env
-                      , HasSettings env
-                      , HasPlatformReq env
-                      , MonadThrow m
-                      , MonadCatch m
-                      , HasLog env
-                      , MonadIO m
-                      , MonadFail m
-                      )
-                   => GHCTargetVersion
-                   -> FilePath
-                   -> InstallDirResolved
-                   -> Excepts
-                        '[ FileDoesNotExistError
-                         , InvalidBuildConfig
-                         , PatchFailed
-                         , ProcessError
-                         , NotFoundInPATH
-                         , CopyError
-                         ]
-                        m
-                        ()
-  configureBindist tver workdir (fromInstallDir -> ghcdir) = do
-    lift $ logInfo [s|configuring build|]
-
-    if | _tvVersion tver >= [vver|8.8.0|] -> do
-          lEM $ execWithGhcEnv
-            "sh"
-            ("./configure" :  maybe mempty
-                      (\x -> ["--target=" <> T.unpack x])
-                      (_tvTarget tver)
-            ++ ["--prefix=" <> ghcdir]
-            ++ (if isWindows then ["--enable-tarballs-autodownload"] else [])
-            ++ fmap T.unpack aargs
-            )
-            (Just workdir)
-            "ghc-conf"
-       | otherwise -> do
-        lEM $ execLogged
-          "sh"
-          (  [ "./configure", "--with-ghc=" <> either id id bghc
-             ]
-          ++ maybe mempty
-                   (\x -> ["--target=" <> T.unpack x])
-                   (_tvTarget tver)
-          ++ ["--prefix=" <> ghcdir]
-          ++ (if isWindows then ["--enable-tarballs-autodownload"] else [])
-          ++ fmap T.unpack aargs
-          )
-          (Just workdir)
-          "ghc-conf"
-          Nothing
-    pure ()
-
-  execWithGhcEnv :: ( MonadReader env m
-                    , HasSettings env
-                    , HasDirs env
-                    , HasLog env
-                    , MonadIO m
-                    , MonadThrow m)
-                 => FilePath         -- ^ thing to execute
-                 -> [String]         -- ^ args for the thing
-                 -> Maybe FilePath   -- ^ optionally chdir into this
-                 -> FilePath         -- ^ log filename (opened in append mode)
-                 -> m (Either ProcessError ())
-  execWithGhcEnv fp args dir logf = do
-    env <- ghcEnv
-    execLogged fp args dir logf (Just env)
-
-  bghc = case bstrap of
-           Right g    -> Right g
-           Left  bver -> Left ("ghc-" <> (T.unpack . prettyVer $ bver) <> exeExt)
-
-  ghcEnv :: (MonadThrow m, MonadIO m) => m [(String, String)]
-  ghcEnv = do
-    cEnv <- liftIO getEnvironment
-    bghcPath <- case bghc of
-      Right ghc' -> pure ghc'
-      Left  bver -> do
-        spaths <- liftIO getSearchPath
-        throwMaybeM (NotFoundInPATH bver) $ liftIO (searchPath spaths bver)
-    pure (("GHC", bghcPath) : cEnv)
-
-
-
-
-
-
-    ---------------------
-    --[ Upgrade GHCup ]--
-    ---------------------
-
-
--- | Upgrade ghcup and place it in @~\/.ghcup\/bin\/ghcup@,
--- if no path is provided.
-upgradeGHCup :: ( MonadMask m
-                , MonadReader env m
-                , HasDirs env
-                , HasPlatformReq env
-                , HasGHCupInfo env
-                , HasSettings env
-                , MonadCatch m
-                , HasLog env
-                , MonadThrow m
-                , MonadFail m
-                , MonadResource m
-                , MonadIO m
-                , MonadUnliftIO m
-                )
-             => Maybe FilePath    -- ^ full file destination to write ghcup into
-             -> Bool              -- ^ whether to force update regardless
-                                  --   of currently installed version
-             -> Bool              -- ^ whether to throw an error if ghcup is shadowed
-             -> Excepts
-                  '[ CopyError
-                   , DigestError
-                   , GPGError
-                   , GPGError
-                   , DownloadFailed
-                   , NoDownload
-                   , NoUpdate
-                   , GHCupShadowed
-                   ]
-                  m
-                  Version
-upgradeGHCup mtarget force' fatal = do
-  Dirs {..} <- lift getDirs
-  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
-
-  lift $ logInfo "Upgrading GHCup..."
-  let latestVer = fst (fromJust (getLatest dls GHCup))
-  (Just ghcupPVPVer) <- pure $ pvpToVersion ghcUpVer ""
-  when (not force' && (latestVer <= ghcupPVPVer)) $ throwE NoUpdate
-  dli   <- liftE $ getDownloadInfo GHCup latestVer
-  tmp   <- lift withGHCupTmpDir
-  let fn = "ghcup" <> exeExt
-  p <- liftE $ download (_dlUri dli) Nothing (Just (_dlHash dli)) tmp (Just fn) False
-  let destDir = takeDirectory destFile
-      destFile = fromMaybe (binDir </> fn) mtarget
-  lift $ logDebug $ "mkdir -p " <> T.pack destDir
-  liftIO $ createDirRecursive' destDir
-  lift $ logDebug $ "rm -f " <> T.pack destFile
-  lift $ hideError NoSuchThing $ recycleFile destFile
-  lift $ logDebug $ "cp " <> T.pack p <> " " <> T.pack destFile
-  copyFileE p
-                                                           destFile
-  lift $ chmod_755 destFile
-
-  liftIO (isInPath destFile) >>= \b -> unless b $
-    lift $ logWarn $ T.pack (takeFileName destFile) <> " is not in PATH! You have to add it in order to use ghcup."
-  liftIO (isShadowed destFile) >>= \case
-    Nothing -> pure ()
-    Just pa
-      | fatal -> throwE (GHCupShadowed pa destFile latestVer)
-      | otherwise ->
-        lift $ logWarn $ "ghcup is shadowed by "
-          <> T.pack pa
-          <> ". The upgrade will not be in effect, unless you remove "
-          <> T.pack pa
-          <> " or make sure "
-          <> T.pack destDir
-          <> " comes before "
-          <> T.pack (takeDirectory pa)
-          <> " in PATH."
-
-  pure latestVer
-
-
-
-    -------------
-    --[ Other ]--
-    -------------
-
-
-
--- | Creates @ghc-x.y.z@ and @ghc-x.y@ symlinks. This is used for
--- both installing from source and bindist.
-postGHCInstall :: ( MonadReader env m
-                  , HasDirs env
-                  , HasLog env
-                  , MonadThrow m
-                  , MonadFail m
-                  , MonadIO m
-                  , MonadCatch m
-                  , MonadMask m
-                  , MonadUnliftIO m
-                  )
-               => GHCTargetVersion
-               -> Excepts '[NotInstalled] m ()
-postGHCInstall ver@GHCTargetVersion {..} = do
-  void $ liftE $ setGHC ver SetGHC_XYZ Nothing
-
-  -- Create ghc-x.y symlinks. This may not be the current
-  -- version, create it regardless.
-  v' <-
-    handle (\(e :: ParseError) -> lift $ logWarn (T.pack $ displayException e) >> pure Nothing)
-    $ fmap Just
-    $ getMajorMinorV _tvVersion
-  forM_ v' $ \(mj, mi) -> lift (getGHCForPVP (PVP (fromIntegral mj :| [fromIntegral mi])) _tvTarget)
-    >>= mapM_ (\v -> liftE $ setGHC v SetGHC_XY Nothing)
-
-
--- | Reports the binary location of a given tool:
---
---   * for GHC, this reports: @~\/.ghcup\/ghc\/\<ver\>\/bin\/ghc@
---   * for cabal, this reports @~\/.ghcup\/bin\/cabal-\<ver\>@
---   * for hls, this reports @~\/.ghcup\/bin\/haskell-language-server-wrapper-\<ver\>@
---   * for stack, this reports @~\/.ghcup\/bin\/stack-\<ver\>@
---   * for ghcup, this reports the location of the currently running executable
-whereIsTool :: ( MonadReader env m
-               , HasDirs env
-               , HasLog env
-               , MonadThrow m
-               , MonadFail m
-               , MonadIO m
-               , MonadCatch m
-               , MonadMask m
-               , MonadUnliftIO m
-               )
-            => Tool
-            -> GHCTargetVersion
-            -> Excepts '[NotInstalled] m FilePath
-whereIsTool tool ver@GHCTargetVersion {..} = do
-  dirs <- lift getDirs
-
-  case tool of
-    GHC -> do
-      whenM (lift $ fmap not $ ghcInstalled ver)
-        $ throwE (NotInstalled GHC ver)
-      bdir <- lift $ ghcupGHCDir ver
-      pure (bdir </> "bin" </> ghcBinaryName ver)
-    Cabal -> do
-      whenM (lift $ fmap not $ cabalInstalled _tvVersion)
-        $ throwE (NotInstalled Cabal (GHCTargetVersion Nothing _tvVersion))
-      pure (binDir dirs </> "cabal-" <> T.unpack (prettyVer _tvVersion) <> exeExt)
-    HLS -> do
-      whenM (lift $ fmap not $ hlsInstalled _tvVersion)
-        $ throwE (NotInstalled HLS (GHCTargetVersion Nothing _tvVersion))
-      ifM (lift $ isLegacyHLS _tvVersion)
-        (pure (binDir dirs </> "haskell-language-server-wrapper-" <> T.unpack (prettyVer _tvVersion) <> exeExt))
-        $ do
-          bdir <- lift $ ghcupHLSDir _tvVersion
-          pure (bdir </> "bin" </> "haskell-language-server-wrapper" <> exeExt)
-
-    Stack -> do
-      whenM (lift $ fmap not $ stackInstalled _tvVersion)
-        $ throwE (NotInstalled Stack (GHCTargetVersion Nothing _tvVersion))
-      pure (binDir dirs </> "stack-" <> T.unpack (prettyVer _tvVersion) <> exeExt)
-    GHCup -> do
-      currentRunningExecPath <- liftIO getExecutablePath
-      liftIO $ canonicalizePath currentRunningExecPath
-
--- | Doesn't work for cross GHC.
-checkIfToolInstalled :: ( MonadIO m
-                        , MonadReader env m
-                        , HasDirs env
-                        , MonadCatch m) =>
-                        Tool ->
-                        Version ->
-                        m Bool
-checkIfToolInstalled tool ver = checkIfToolInstalled' tool (mkTVer ver)
-
-checkIfToolInstalled' :: ( MonadIO m
-                         , MonadReader env m
-                         , HasDirs env
-                         , MonadCatch m) =>
-                        Tool ->
-                        GHCTargetVersion ->
-                        m Bool
-checkIfToolInstalled' tool ver =
-  case tool of
-    Cabal -> cabalInstalled (_tvVersion ver)
-    HLS   -> hlsInstalled (_tvVersion ver)
-    Stack -> stackInstalled (_tvVersion ver)
-    GHC   -> ghcInstalled ver
-    _     -> pure False
-
-throwIfFileAlreadyExists :: ( MonadIO m ) =>
-                            FilePath ->
-                            Excepts '[FileAlreadyExistsError] m ()
-
-throwIfFileAlreadyExists fp = whenM (checkFileAlreadyExists fp)
-                                (throwE $ FileAlreadyExistsError fp)
-
-
-
-    --------------------------
-    --[ Garbage collection ]--
-    --------------------------
-
-
-rmOldGHC :: ( MonadReader env m
-            , HasGHCupInfo env
-            , HasDirs env
-            , HasLog env
-            , MonadIO m
-            , MonadFail m
-            , MonadMask m
-            , MonadUnliftIO m
-            )
-         => Excepts '[NotInstalled] m ()
-rmOldGHC = do
-  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
-  let oldGHCs = mkTVer <$> toListOf (ix GHC % getTagged Old % to fst) dls
-  ghcs <- lift $ fmap rights getInstalledGHCs
-  forM_ ghcs $ \ghc -> when (ghc `elem` oldGHCs) $ rmGHCVer ghc
-
-
-
-rmProfilingLibs :: ( MonadReader env m
-                   , HasDirs env
-                   , HasLog env
-                   , MonadIO m
-                   , MonadFail m
-                   , MonadMask m
-                   , MonadUnliftIO m
-                   )
-                => m ()
-rmProfilingLibs = do
-  ghcs <- fmap rights getInstalledGHCs
-
-  let regexes :: [ByteString]
-      regexes = [[s|.*_p\.a$|], [s|.*\.p_hi$|]]
-
-  forM_ regexes $ \regex ->
-    forM_ ghcs $ \ghc -> do
-      d <- ghcupGHCDir ghc
-      matches <- liftIO $ handleIO (\_ -> pure []) $ findFilesDeep
-        d
-        (makeRegexOpts compExtended
-                       execBlank
-                       regex
-        )
-      forM_ matches $ \m -> do
-        let p = d </> m
-        logDebug $ "rm " <> T.pack p
-        rmFile p
-
-
-
-rmShareDir :: ( MonadReader env m
-              , HasDirs env
-              , HasLog env
-              , MonadIO m
-              , MonadFail m
-              , MonadMask m
-              , MonadUnliftIO m
-              )
-           => m ()
-rmShareDir = do
-  ghcs <- fmap rights getInstalledGHCs
-  forM_ ghcs $ \ghc -> do
-    d <- ghcupGHCDir ghc
-    let p = d </> "share"
-    logDebug $ "rm -rf " <> T.pack p
-    rmPathForcibly p
-
-
-rmHLSNoGHC :: ( MonadReader env m
-              , HasDirs env
-              , HasLog env
-              , MonadIO m
-              , MonadMask m
-              , MonadFail m
-              , MonadUnliftIO m
-              )
-           => Excepts '[NotInstalled] m ()
-rmHLSNoGHC = do
-  Dirs {..} <- getDirs
-  ghcs <- fmap rights getInstalledGHCs
-  hlses <- fmap rights getInstalledHLSs
-  forM_ hlses $ \hls -> do
-    hlsGHCs <- fmap mkTVer <$> hlsGHCVersions' hls
-    let candidates = filter (`notElem` ghcs) hlsGHCs
-    if (length hlsGHCs - length candidates) <= 0
-    then rmHLSVer hls
-    else
-      forM_ candidates $ \ghc -> do
-        bins1 <- fmap (binDir </>) <$> hlsServerBinaries hls (Just $ _tvVersion ghc)
-        bins2 <- ifM (isLegacyHLS hls) (pure []) $ do
-          shs <- hlsInternalServerScripts hls (Just $ _tvVersion ghc)
-          bins <- hlsInternalServerBinaries hls (Just $ _tvVersion ghc)
-          libs <- hlsInternalServerLibs hls (_tvVersion ghc)
-          pure (shs ++ bins ++ libs)
-        forM_ (bins1 ++ bins2) $ \f -> do
-          logDebug $ "rm " <> T.pack f
-          rmFile f
-    pure ()
-
-
-rmCache :: ( MonadReader env m
-           , HasDirs env
-           , HasLog env
-           , MonadIO m
-           , MonadMask m
-           )
-        => m ()
-rmCache = do
-  Dirs {..} <- getDirs
-  contents <- liftIO $ listDirectory cacheDir
-  forM_ contents $ \f -> do
-    let p = cacheDir </> f
-    logDebug $ "rm " <> T.pack p
-    rmFile p
-
-
-rmTmp :: ( MonadReader env m
-         , HasDirs env
-         , HasLog env
-         , MonadIO m
-         , MonadMask m
-         )
-      => m ()
-rmTmp = do
-  tmpdir <- liftIO getCanonicalTemporaryDirectory
-  ghcup_dirs <- liftIO $ handleIO (\_ -> pure []) $ findFiles
-    tmpdir
-    (makeRegexOpts compExtended
-                   execBlank
-                   ([s|^ghcup-.*$|] :: ByteString)
-    )
-  forM_ ghcup_dirs $ \f -> do
-    let p = tmpdir </> f
-    logDebug $ "rm -rf " <> T.pack p
-    rmPathForcibly p
-
-
-applyAnyPatch :: ( MonadReader env m
-                 , HasDirs env
-                 , HasLog env
-                 , HasSettings env
-                 , MonadUnliftIO m
-                 , MonadCatch m
-                 , MonadResource m
-                 , MonadThrow m
-                 , MonadMask m
-                 , MonadIO m)
-              => Maybe (Either FilePath [URI])
-              -> FilePath
-              -> Excepts '[PatchFailed, DownloadFailed, DigestError, GPGError] m ()
-applyAnyPatch Nothing _                   = pure ()
-applyAnyPatch (Just (Left pdir)) workdir  = liftE $ applyPatches pdir workdir
-applyAnyPatch (Just (Right uris)) workdir = do
-  tmpUnpack <- lift withGHCupTmpDir
-  forM_ uris $ \uri -> do
-    patch <- liftE $ download uri Nothing Nothing tmpUnpack Nothing False
-    liftE $ applyPatch patch workdir
+
+{-|
+Module      : GHCup
+Description : GHCup installation functions
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+
+This module contains the main functions that correspond
+to the command line interface, like installation, listing versions
+and so on.
+
+These are the entry points.
+-}
+module GHCup (
+  module GHCup,
+  module GHCup.Cabal,
+  module GHCup.GHC,
+  module GHCup.HLS,
+  module GHCup.Stack,
+  module GHCup.List
+) where
+
+
+import           GHCup.Cabal
+import           GHCup.GHC             hiding ( GHCVer(..) )
+import           GHCup.HLS             hiding ( HLSVer(..) )
+import           GHCup.Stack
+import           GHCup.List
+import           GHCup.Download
+import           GHCup.Errors
+import           GHCup.Platform
+import           GHCup.Types
+import           GHCup.Types.JSON               ( )
+import           GHCup.Types.Optics
+import           GHCup.Utils
+import           GHCup.Prelude
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.String.QQ
+import           GHCup.Version
+
+import           Control.Applicative
+import           Control.Exception.Safe
+import           Control.Monad
+#if !MIN_VERSION_base(4,13,0)
+import           Control.Monad.Fail             ( MonadFail )
+#endif
+import           Control.Monad.Reader
+import           Control.Monad.Trans.Resource
+                                         hiding ( throwM )
+import           Data.ByteString                ( ByteString )
+import           Data.Either
+import           Data.List
+import           Data.Maybe
+import           Data.Versions                hiding ( patch )
+import           GHC.IO.Exception
+import           Haskus.Utils.Variant.Excepts
+import           Optics
+import           Prelude                 hiding ( abs
+                                                , writeFile
+                                                )
+import           System.Environment
+import           System.FilePath
+import           System.IO.Error
+import           Text.Regex.Posix
+
+import qualified Data.Text                     as T
+import qualified Streamly.Prelude              as S
+import Text.PrettyPrint.HughesPJClass (prettyShow)
+
+
+
+
+    ---------------------
+    --[ Tool fetching ]--
+    ---------------------
+
+
+fetchToolBindist :: ( MonadFail m
+                    , MonadMask m
+                    , MonadCatch m
+                    , MonadReader env m
+                    , HasDirs env
+                    , HasSettings env
+                    , HasPlatformReq env
+                    , HasGHCupInfo env
+                    , HasLog env
+                    , MonadResource m
+                    , MonadIO m
+                    , MonadUnliftIO m
+                    )
+                 => Version
+                 -> Tool
+                 -> Maybe FilePath
+                 -> Excepts
+                      '[ DigestError
+                       , GPGError
+                       , DownloadFailed
+                       , NoDownload
+                       ]
+                      m
+                      FilePath
+fetchToolBindist v t mfp = do
+  dlinfo <- liftE $ getDownloadInfo t v
+  liftE $ downloadCached' dlinfo Nothing mfp
+
+
+
+    ------------
+    --[ Nuke ]--
+    ------------
+
+
+
+
+rmTool :: ( MonadReader env m
+          , HasDirs env
+          , HasLog env
+          , MonadFail m
+          , MonadMask m
+          , MonadUnliftIO m)
+          => ListResult
+          -> Excepts '[NotInstalled, UninstallFailed] m ()
+rmTool ListResult {lVer, lTool, lCross} = do
+  case lTool of
+    GHC ->
+      let ghcTargetVersion = GHCTargetVersion lCross lVer
+      in rmGHCVer ghcTargetVersion
+    HLS -> rmHLSVer lVer
+    Cabal -> liftE $ rmCabalVer lVer
+    Stack -> liftE $ rmStackVer lVer
+    GHCup -> lift rmGhcup
+
+
+rmGhcupDirs :: ( MonadReader env m
+               , HasDirs env
+               , MonadIO m
+               , HasLog env
+               , MonadCatch m
+               , MonadMask m )
+            => m [FilePath]
+rmGhcupDirs = do
+  Dirs
+    { baseDir
+    , binDir
+    , logsDir
+    , cacheDir
+    , recycleDir
+    , dbDir
+    , tmpDir
+    } <- getDirs
+
+  let envFilePath = fromGHCupPath baseDir </> "env"
+
+  confFilePath <- getConfigFilePath
+
+  handleRm $ rmEnvFile  envFilePath
+  handleRm $ rmConfFile confFilePath
+
+  -- for xdg dirs, the order matters here
+  handleRm $ rmPathForcibly logsDir
+  handleRm $ rmPathForcibly tmpDir
+  handleRm $ rmPathForcibly cacheDir
+
+  handleRm $ rmBinDir binDir
+  handleRm $ rmPathForcibly recycleDir
+  handleRm $ rmPathForcibly dbDir
+  when isWindows $ do
+    logInfo $ "removing " <> T.pack (fromGHCupPath baseDir </> "msys64")
+    handleRm $ rmPathForcibly (baseDir `appendGHCupPath` "msys64")
+
+  handleRm $ removeEmptyDirsRecursive (fromGHCupPath baseDir)
+
+  -- report files in baseDir that are left-over after
+  -- the standard location deletions above
+  hideErrorDef [doesNotExistErrorType] [] $ reportRemainingFiles (fromGHCupPath baseDir)
+
+  where
+    handleRm :: (MonadReader env m, MonadCatch m, HasLog env, MonadIO m)  => m () -> m ()
+    handleRm = handleIO (\e -> logDebug $ "Part of the cleanup action failed with error: " <> T.pack (displayException e) <> "\n"
+                                <> "continuing regardless...")
+
+    rmEnvFile :: (HasLog env, MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
+    rmEnvFile enFilePath = do
+      logInfo "Removing Ghcup Environment File"
+      hideErrorDef [permissionErrorType] () $ rmFileForce enFilePath
+
+    rmConfFile :: (HasLog env, MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
+    rmConfFile confFilePath = do
+      logInfo "removing Ghcup Config File"
+      hideErrorDef [permissionErrorType] () $ rmFileForce confFilePath
+
+    rmBinDir :: (MonadReader env m, HasDirs env, MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
+    rmBinDir binDir
+      | isWindows = removeDirIfEmptyOrIsSymlink binDir
+      | otherwise = do
+          isXDGStyle <- liftIO useXDG
+          when (not isXDGStyle) $
+            removeDirIfEmptyOrIsSymlink binDir
+
+    reportRemainingFiles :: (MonadMask m, MonadIO m) => FilePath -> m [FilePath]
+    reportRemainingFiles dir = do
+      remainingFiles <- liftIO $ S.toList (getDirectoryContentsRecursiveUnsafe dir)
+      let normalizedFilePaths = fmap normalise remainingFiles
+      let sortedByDepthRemainingFiles = sortBy (flip compareFn) normalizedFilePaths
+      let remainingFilesAbsolute = fmap (dir </>) sortedByDepthRemainingFiles
+
+      pure remainingFilesAbsolute
+
+      where
+        calcDepth :: FilePath -> Int
+        calcDepth = length . filter isPathSeparator
+
+        compareFn :: FilePath -> FilePath -> Ordering
+        compareFn fp1 fp2 = compare (calcDepth fp1) (calcDepth fp2)
+
+
+
+
+    ------------------
+    --[ Debug info ]--
+    ------------------
+
+
+getDebugInfo :: ( Alternative m
+                , MonadFail m
+                , MonadReader env m
+                , HasDirs env
+                , HasLog env
+                , MonadCatch m
+                , MonadIO m
+                )
+             => Excepts
+                  '[NoCompatiblePlatform , NoCompatibleArch , DistroNotFound]
+                  m
+                  DebugInfo
+getDebugInfo = do
+  Dirs {..} <- lift getDirs
+  let diBaseDir  = fromGHCupPath baseDir
+  let diBinDir   = binDir
+  diGHCDir       <- fromGHCupPath <$> lift ghcupGHCBaseDir
+  let diCacheDir = fromGHCupPath cacheDir
+  diArch         <- lE getArchitecture
+  diPlatform     <- liftE getPlatform
+  pure $ DebugInfo { .. }
+
+
+
+
+    -------------------------
+    --[ GHCup upgrade etc ]--
+    -------------------------
+
+
+-- | Upgrade ghcup and place it in @~\/.ghcup\/bin\/ghcup@,
+-- if no path is provided.
+upgradeGHCup :: ( MonadMask m
+                , MonadReader env m
+                , HasDirs env
+                , HasPlatformReq env
+                , HasGHCupInfo env
+                , HasSettings env
+                , MonadCatch m
+                , HasLog env
+                , MonadThrow m
+                , MonadFail m
+                , MonadResource m
+                , MonadIO m
+                , MonadUnliftIO m
+                )
+             => Maybe FilePath    -- ^ full file destination to write ghcup into
+             -> Bool              -- ^ whether to force update regardless
+                                  --   of currently installed version
+             -> Bool              -- ^ whether to throw an error if ghcup is shadowed
+             -> Excepts
+                  '[ CopyError
+                   , DigestError
+                   , GPGError
+                   , GPGError
+                   , DownloadFailed
+                   , NoDownload
+                   , NoUpdate
+                   , ToolShadowed
+                   ]
+                  m
+                  Version
+upgradeGHCup mtarget force' fatal = do
+  Dirs {..} <- lift getDirs
+  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
+
+  lift $ logInfo "Upgrading GHCup..."
+  let latestVer = fst (fromJust (getLatest dls GHCup))
+  (Just ghcupPVPVer) <- pure $ pvpToVersion ghcUpVer ""
+  when (not force' && (latestVer <= ghcupPVPVer)) $ throwE NoUpdate
+  dli   <- liftE $ getDownloadInfo GHCup latestVer
+  tmp   <- fromGHCupPath <$> lift withGHCupTmpDir
+  let fn = "ghcup" <> exeExt
+  p <- liftE $ download (_dlUri dli) Nothing (Just (_dlHash dli)) tmp (Just fn) False
+  let destDir = takeDirectory destFile
+      destFile = fromMaybe (binDir </> fn) mtarget
+  lift $ logDebug $ "mkdir -p " <> T.pack destDir
+  liftIO $ createDirRecursive' destDir
+  lift $ logDebug $ "rm -f " <> T.pack destFile
+  lift $ hideError NoSuchThing $ recycleFile destFile
+  lift $ logDebug $ "cp " <> T.pack p <> " " <> T.pack destFile
+  copyFileE p destFile False
+  lift $ chmod_755 destFile
+
+  liftIO (isInPath destFile) >>= \b -> unless b $
+    lift $ logWarn $ T.pack (takeFileName destFile) <> " is not in PATH! You have to add it in order to use ghcup."
+  liftIO (isShadowed destFile) >>= \case
+    Nothing -> pure ()
+    Just pa
+      | fatal -> throwE (ToolShadowed GHCup pa destFile latestVer)
+      | otherwise ->
+        lift $ logWarn $ T.pack $ prettyShow (ToolShadowed GHCup pa destFile latestVer)
+
+  pure latestVer
+
+
+-- assuming the current scheme of having just 1 ghcup bin, no version info is required.
+rmGhcup :: ( MonadReader env m
+           , HasDirs env
+           , MonadIO m
+           , MonadCatch m
+           , HasLog env
+           , MonadMask m
+           , MonadUnliftIO m
+           )
+        => m ()
+rmGhcup = do
+  Dirs { .. } <- getDirs
+  let ghcupFilename = "ghcup" <> exeExt
+  let ghcupFilepath = binDir </> ghcupFilename
+
+  currentRunningExecPath <- liftIO getExecutablePath
+
+  -- if paths do no exist, warn user, and continue to compare them, as is,
+  -- which should eventually fail and result in a non-standard install warning
+
+  p1 <- handleIO' doesNotExistErrorType
+                  (handlePathNotPresent currentRunningExecPath)
+                  (liftIO $ canonicalizePath currentRunningExecPath)
+
+  p2 <- handleIO' doesNotExistErrorType
+                  (handlePathNotPresent ghcupFilepath)
+                  (liftIO $ canonicalizePath ghcupFilepath)
+
+  let areEqualPaths = equalFilePath p1 p2
+
+  unless areEqualPaths $ logWarn $ nonStandardInstallLocationMsg currentRunningExecPath
+
+  if isWindows
+  then do
+    -- since it doesn't seem possible to delete a running exe on windows
+    -- we move it to temp dir, to be deleted at next reboot
+    tempFilepath <- mkGhcupTmpDir
+    hideError UnsupportedOperation $
+              liftIO $ hideError NoSuchThing $
+              moveFile ghcupFilepath (fromGHCupPath tempFilepath </> "ghcup")
+  else
+    -- delete it.
+    hideError doesNotExistErrorType $ rmFile ghcupFilepath
+
+  where
+    handlePathNotPresent fp _err = do
+      logDebug $ "Error: The path does not exist, " <> T.pack fp
+      pure fp
+
+    nonStandardInstallLocationMsg path = T.pack $
+      "current ghcup is invoked from a non-standard location: \n"
+      <> path <>
+      "\n you may have to uninstall it manually."
+
+
+
+    ---------------
+    --[ Whereis ]--
+    ---------------
+
+
+
+-- | Reports the binary location of a given tool:
+--
+--   * for GHC, this reports: @~\/.ghcup\/ghc\/\<ver\>\/bin\/ghc@
+--   * for cabal, this reports @~\/.ghcup\/bin\/cabal-\<ver\>@
+--   * for hls, this reports @~\/.ghcup\/bin\/haskell-language-server-wrapper-\<ver\>@
+--   * for stack, this reports @~\/.ghcup\/bin\/stack-\<ver\>@
+--   * for ghcup, this reports the location of the currently running executable
+whereIsTool :: ( MonadReader env m
+               , HasDirs env
+               , HasLog env
+               , MonadThrow m
+               , MonadFail m
+               , MonadIO m
+               , MonadCatch m
+               , MonadMask m
+               , MonadUnliftIO m
+               )
+            => Tool
+            -> GHCTargetVersion
+            -> Excepts '[NotInstalled] m FilePath
+whereIsTool tool ver@GHCTargetVersion {..} = do
+  dirs <- lift getDirs
+
+  case tool of
+    GHC -> do
+      whenM (lift $ fmap not $ ghcInstalled ver)
+        $ throwE (NotInstalled GHC ver)
+      bdir <- fromGHCupPath <$> lift (ghcupGHCDir ver)
+      pure (bdir </> "bin" </> ghcBinaryName ver)
+    Cabal -> do
+      whenM (lift $ fmap not $ cabalInstalled _tvVersion)
+        $ throwE (NotInstalled Cabal (GHCTargetVersion Nothing _tvVersion))
+      pure (binDir dirs </> "cabal-" <> T.unpack (prettyVer _tvVersion) <> exeExt)
+    HLS -> do
+      whenM (lift $ fmap not $ hlsInstalled _tvVersion)
+        $ throwE (NotInstalled HLS (GHCTargetVersion Nothing _tvVersion))
+      ifM (lift $ isLegacyHLS _tvVersion)
+        (pure (binDir dirs </> "haskell-language-server-wrapper-" <> T.unpack (prettyVer _tvVersion) <> exeExt))
+        $ do
+          bdir <- fromGHCupPath <$> lift (ghcupHLSDir _tvVersion)
+          pure (bdir </> "bin" </> "haskell-language-server-wrapper" <> exeExt)
+
+    Stack -> do
+      whenM (lift $ fmap not $ stackInstalled _tvVersion)
+        $ throwE (NotInstalled Stack (GHCTargetVersion Nothing _tvVersion))
+      pure (binDir dirs </> "stack-" <> T.unpack (prettyVer _tvVersion) <> exeExt)
+    GHCup -> do
+      currentRunningExecPath <- liftIO getExecutablePath
+      liftIO $ canonicalizePath currentRunningExecPath
+
+
+-- | Doesn't work for cross GHC.
+checkIfToolInstalled :: ( MonadIO m
+                        , MonadReader env m
+                        , HasDirs env
+                        , MonadCatch m) =>
+                        Tool ->
+                        Version ->
+                        m Bool
+checkIfToolInstalled tool ver = checkIfToolInstalled' tool (mkTVer ver)
+
+
+checkIfToolInstalled' :: ( MonadIO m
+                         , MonadReader env m
+                         , HasDirs env
+                         , MonadCatch m) =>
+                        Tool ->
+                        GHCTargetVersion ->
+                        m Bool
+checkIfToolInstalled' tool ver =
+  case tool of
+    Cabal -> cabalInstalled (_tvVersion ver)
+    HLS   -> hlsInstalled (_tvVersion ver)
+    Stack -> stackInstalled (_tvVersion ver)
+    GHC   -> ghcInstalled ver
+    _     -> pure False
+
+
+
+
+    --------------------------
+    --[ Garbage collection ]--
+    --------------------------
+
+
+rmOldGHC :: ( MonadReader env m
+            , HasGHCupInfo env
+            , HasDirs env
+            , HasLog env
+            , MonadIO m
+            , MonadFail m
+            , MonadMask m
+            , MonadUnliftIO m
+            )
+         => Excepts '[NotInstalled, UninstallFailed] m ()
+rmOldGHC = do
+  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
+  let oldGHCs = mkTVer <$> toListOf (ix GHC % getTagged Old % to fst) dls
+  ghcs <- lift $ fmap rights getInstalledGHCs
+  forM_ ghcs $ \ghc -> when (ghc `elem` oldGHCs) $ rmGHCVer ghc
+
+
+
+rmProfilingLibs :: ( MonadReader env m
+                   , HasDirs env
+                   , HasLog env
+                   , MonadIO m
+                   , MonadFail m
+                   , MonadMask m
+                   , MonadUnliftIO m
+                   )
+                => m ()
+rmProfilingLibs = do
+  ghcs <- fmap rights getInstalledGHCs
+
+  let regexes :: [ByteString]
+      regexes = [[s|.*_p\.a$|], [s|.*\.p_hi$|]]
+
+  forM_ regexes $ \regex ->
+    forM_ ghcs $ \ghc -> do
+      d <- ghcupGHCDir ghc
+      -- TODO: audit findFilesDeep
+      matches <- liftIO $ handleIO (\_ -> pure []) $ findFilesDeep
+        d
+        (makeRegexOpts compExtended
+                       execBlank
+                       regex
+        )
+      forM_ matches $ \m -> do
+        let p = fromGHCupPath d </> m
+        logDebug $ "rm " <> T.pack p
+        rmFile p
+
+
+
+rmShareDir :: ( MonadReader env m
+              , HasDirs env
+              , HasLog env
+              , MonadIO m
+              , MonadFail m
+              , MonadMask m
+              , MonadUnliftIO m
+              )
+           => m ()
+rmShareDir = do
+  ghcs <- fmap rights getInstalledGHCs
+  forM_ ghcs $ \ghc -> do
+    d <- ghcupGHCDir ghc
+    let p = d `appendGHCupPath` "share"
+    logDebug $ "rm -rf " <> T.pack (fromGHCupPath p)
+    rmPathForcibly p
+
+
+rmHLSNoGHC :: ( MonadReader env m
+              , HasDirs env
+              , HasLog env
+              , MonadIO m
+              , MonadMask m
+              , MonadFail m
+              , MonadUnliftIO m
+              )
+           => Excepts '[NotInstalled, UninstallFailed] m ()
+rmHLSNoGHC = do
+  Dirs {..} <- getDirs
+  ghcs <- fmap rights getInstalledGHCs
+  hlses <- fmap rights getInstalledHLSs
+  forM_ hlses $ \hls -> do
+    hlsGHCs <- fmap mkTVer <$> hlsGHCVersions' hls
+    let candidates = filter (`notElem` ghcs) hlsGHCs
+    if (length hlsGHCs - length candidates) <= 0
+    then rmHLSVer hls
+    else
+      forM_ candidates $ \ghc -> do
+        bins1 <- fmap (binDir </>) <$> hlsServerBinaries hls (Just $ _tvVersion ghc)
+        bins2 <- ifM (isLegacyHLS hls) (pure []) $ do
+          shs <- hlsInternalServerScripts hls (Just $ _tvVersion ghc)
+          bins <- hlsInternalServerBinaries hls (Just $ _tvVersion ghc)
+          libs <- hlsInternalServerLibs hls (_tvVersion ghc)
+          pure (shs ++ bins ++ libs)
+        forM_ (bins1 ++ bins2) $ \f -> do
+          logDebug $ "rm " <> T.pack f
+          rmFile f
+    pure ()
+
+
+rmCache :: ( MonadReader env m
+           , HasDirs env
+           , HasLog env
+           , MonadIO m
+           , MonadMask m
+           )
+        => m ()
+rmCache = do
+  Dirs {..} <- getDirs
+  contents <- liftIO $ listDirectory (fromGHCupPath cacheDir)
+  forM_ contents $ \f -> do
+    let p = fromGHCupPath cacheDir </> f
+    logDebug $ "rm " <> T.pack p
+    rmFile p
+
+
+rmTmp :: ( MonadReader env m
+         , HasDirs env
+         , HasLog env
+         , MonadIO m
+         , MonadMask m
+         )
+      => m ()
+rmTmp = do
+  ghcup_dirs <- liftIO getGHCupTmpDirs
+  forM_ ghcup_dirs $ \f -> do
+    logDebug $ "rm -rf " <> T.pack (fromGHCupPath f)
+    rmPathForcibly f
+
+
diff --git a/lib/GHCup/Cabal.hs b/lib/GHCup/Cabal.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Cabal.hs
@@ -0,0 +1,284 @@
+{-# LANGUAGE CPP                   #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings     #-}
+
+{-|
+Module      : GHCup.Cabal
+Description : GHCup installation functions for Cabal
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+-}
+module GHCup.Cabal where
+
+import           GHCup.Download
+import           GHCup.Errors
+import           GHCup.Types
+import           GHCup.Types.JSON               ( )
+import           GHCup.Types.Optics
+import           GHCup.Utils
+import           GHCup.Prelude
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger
+
+import           Codec.Archive                  ( ArchiveResult )
+import           Control.Applicative
+import           Control.Exception.Safe
+import           Control.Monad
+#if !MIN_VERSION_base(4,13,0)
+import           Control.Monad.Fail             ( MonadFail )
+#endif
+import           Control.Monad.Reader
+import           Control.Monad.Trans.Resource
+                                         hiding ( throwM )
+import           Data.Either
+import           Data.List
+import           Data.Maybe
+import           Data.Versions                hiding ( patch )
+import           Haskus.Utils.Variant.Excepts
+import           Optics
+import           Prelude                 hiding ( abs
+                                                , writeFile
+                                                )
+import           Safe                    hiding ( at )
+import           System.FilePath
+import           System.IO.Error
+
+import qualified Data.Text                     as T
+import Text.PrettyPrint.HughesPJClass (prettyShow)
+
+
+
+    -------------------------
+    --[ Tool installation ]--
+    -------------------------
+
+
+-- | Like 'installCabalBin', except takes the 'DownloadInfo' as
+-- argument instead of looking it up from 'GHCupDownloads'.
+installCabalBindist :: ( MonadMask m
+                       , MonadCatch m
+                       , MonadReader env m
+                       , HasPlatformReq env
+                       , HasDirs env
+                       , HasSettings env
+                       , HasLog env
+                       , MonadResource m
+                       , MonadIO m
+                       , MonadUnliftIO m
+                       , MonadFail m
+                       )
+                    => DownloadInfo
+                    -> Version
+                    -> InstallDir
+                    -> Bool           -- ^ Force install
+                    -> Excepts
+                         '[ AlreadyInstalled
+                          , CopyError
+                          , DigestError
+                          , GPGError
+                          , DownloadFailed
+                          , NoDownload
+                          , NotInstalled
+                          , UnknownArchive
+                          , TarDirDoesNotExist
+                          , ArchiveResult
+                          , FileAlreadyExistsError
+                          ]
+                         m
+                         ()
+installCabalBindist dlinfo ver installDir forceInstall = do
+  lift $ logDebug $ "Requested to install cabal version " <> prettyVer ver
+
+  PlatformRequest {..} <- lift getPlatformReq
+  Dirs {..} <- lift getDirs
+
+  -- check if we already have a regular cabal already installed
+  regularCabalInstalled <- lift $ cabalInstalled ver
+
+  if
+    | not forceInstall
+    , regularCabalInstalled
+    , GHCupInternal <- installDir -> do
+        throwE $ AlreadyInstalled Cabal ver
+
+    | forceInstall
+    , regularCabalInstalled
+    , GHCupInternal <- installDir -> do
+        lift $ logInfo "Removing the currently installed version first!"
+        liftE $ rmCabalVer ver
+
+    | otherwise -> pure ()
+
+
+  -- download (or use cached version)
+  dl <- liftE $ downloadCached dlinfo Nothing
+
+  -- unpack
+  tmpUnpack <- lift withGHCupTmpDir
+  liftE $ cleanUpOnError tmpUnpack (unpackToDir (fromGHCupPath tmpUnpack) dl)
+  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpUnpack)
+
+  -- the subdir of the archive where we do the work
+  workdir <- fromGHCupPath <$> maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
+
+  case installDir of
+    IsolateDir isoDir -> do             -- isolated install
+      lift $ logInfo $ "isolated installing Cabal to " <> T.pack isoDir
+      liftE $ installCabalUnpacked workdir (IsolateDirResolved isoDir) ver forceInstall
+
+    GHCupInternal -> do                 -- regular install
+      liftE $ installCabalUnpacked workdir (GHCupBinDir binDir) ver forceInstall
+
+
+-- | Install an unpacked cabal distribution.Symbol
+installCabalUnpacked :: (MonadCatch m, HasLog env, MonadIO m, MonadReader env m)
+              => FilePath      -- ^ Path to the unpacked cabal bindist (where the executable resides)
+              -> InstallDirResolved      -- ^ Path to install to
+              -> Version
+              -> Bool          -- ^ Force Install
+              -> Excepts '[CopyError, FileAlreadyExistsError] m ()
+installCabalUnpacked path inst ver forceInstall = do
+  lift $ logInfo "Installing cabal"
+  let cabalFile = "cabal"
+  liftIO $ createDirRecursive' (fromInstallDir inst)
+  let destFileName = cabalFile
+        <> (case inst of
+              IsolateDirResolved _ -> ""
+              _ -> ("-" <>) . T.unpack . prettyVer $ ver
+           )
+        <> exeExt
+  let destPath = fromInstallDir inst </> destFileName
+
+  copyFileE
+    (path </> cabalFile <> exeExt)
+    destPath
+    (not forceInstall)
+  lift $ chmod_755 destPath
+
+-- | Installs cabal into @~\/.ghcup\/bin/cabal-\<ver\>@ and
+-- creates a default @cabal -> cabal-x.y.z.q@ symlink for
+-- the latest installed version.
+installCabalBin :: ( MonadMask m
+                   , MonadCatch m
+                   , MonadReader env m
+                   , HasPlatformReq env
+                   , HasGHCupInfo env
+                   , HasDirs env
+                   , HasSettings env
+                   , HasLog env
+                   , MonadResource m
+                   , MonadIO m
+                   , MonadUnliftIO m
+                   , MonadFail m
+                   )
+                => Version
+                -> InstallDir
+                -> Bool           -- force install
+                -> Excepts
+                     '[ AlreadyInstalled
+                      , CopyError
+                      , DigestError
+                      , GPGError
+                      , DownloadFailed
+                      , NoDownload
+                      , NotInstalled
+                      , UnknownArchive
+                      , TarDirDoesNotExist
+                      , ArchiveResult
+                      , FileAlreadyExistsError
+                      ]
+                     m
+                     ()
+installCabalBin ver installDir forceInstall = do
+  dlinfo <- liftE $ getDownloadInfo Cabal ver
+  installCabalBindist dlinfo ver installDir forceInstall
+
+
+    -----------------
+    --[ Set cabal ]--
+    -----------------
+
+
+-- | Set the @~\/.ghcup\/bin\/cabal@ symlink.
+setCabal :: ( MonadMask m
+            , MonadReader env m
+            , HasDirs env
+            , HasLog env
+            , MonadFail m
+            , MonadIO m
+            , MonadUnliftIO m)
+         => Version
+         -> Excepts '[NotInstalled] m ()
+setCabal ver = do
+  let targetFile = "cabal-" <> T.unpack (prettyVer ver) <> exeExt
+
+  -- symlink destination
+  Dirs {..} <- lift getDirs
+
+  whenM (liftIO $ not <$> doesFileExist (binDir </> targetFile))
+    $ throwE
+    $ NotInstalled Cabal (GHCTargetVersion Nothing ver)
+
+  let cabalbin = binDir </> "cabal" <> exeExt
+
+  -- create link
+  let destL = targetFile
+  lift $ createLink destL cabalbin
+
+  liftIO (isShadowed cabalbin) >>= \case
+    Nothing -> pure ()
+    Just pa -> lift $ logWarn $ T.pack $ prettyShow (ToolShadowed Cabal pa cabalbin ver)
+
+  pure ()
+
+unsetCabal :: ( MonadMask m
+              , MonadReader env m
+              , HasDirs env
+              , MonadIO m)
+           => m ()
+unsetCabal = do
+  Dirs {..} <- getDirs
+  let cabalbin = binDir </> "cabal" <> exeExt
+  hideError doesNotExistErrorType $ rmLink cabalbin
+
+
+    ----------------
+    --[ Rm cabal ]--
+    ----------------
+
+
+-- | Delete a cabal version. Will try to fix the @cabal@ symlink
+-- after removal (e.g. setting it to an older version).
+rmCabalVer :: ( MonadMask m
+              , MonadReader env m
+              , HasDirs env
+              , MonadThrow m
+              , HasLog env
+              , MonadIO m
+              , MonadFail m
+              , MonadCatch m
+              , MonadUnliftIO m
+              )
+           => Version
+           -> Excepts '[NotInstalled] m ()
+rmCabalVer ver = do
+  whenM (lift $ fmap not $ cabalInstalled ver) $ throwE (NotInstalled Cabal (GHCTargetVersion Nothing ver))
+
+  cSet      <- lift cabalSet
+
+  Dirs {..} <- lift getDirs
+
+  let cabalFile = "cabal-" <> T.unpack (prettyVer ver) <> exeExt
+  lift $ hideError doesNotExistErrorType $ recycleFile (binDir </> cabalFile)
+
+  when (Just ver == cSet) $ do
+    cVers <- lift $ fmap rights getInstalledCabals
+    case headMay . reverse . sort $ cVers of
+      Just latestver -> setCabal latestver
+      Nothing        -> lift $ rmLink (binDir </> "cabal" <> exeExt)
diff --git a/lib/GHCup/Download.hs b/lib/GHCup/Download.hs
--- a/lib/GHCup/Download.hs
+++ b/lib/GHCup/Download.hs
@@ -34,9 +34,10 @@
 import           GHCup.Types.Optics
 import           GHCup.Types.JSON               ( )
 import           GHCup.Utils.Dirs
-import           GHCup.Utils.File
-import           GHCup.Utils.Logger
-import           GHCup.Utils.Prelude
+import           GHCup.Prelude
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger.Internal
+import           GHCup.Prelude.Process
 import           GHCup.Version
 
 import           Control.Applicative
@@ -69,7 +70,6 @@
                                                 , writeFile
                                                 )
 import           Safe
-import           System.Directory
 import           System.Environment
 import           System.Exit
 import           System.FilePath
@@ -145,7 +145,7 @@
 yamlFromCache :: (MonadReader env m, HasDirs env) => URI -> m FilePath
 yamlFromCache uri = do
   Dirs{..} <- getDirs
-  pure (cacheDir </> (T.unpack . decUTF8Safe . urlBaseName . view pathL' $ uri))
+  pure (fromGHCupPath cacheDir </> (T.unpack . decUTF8Safe . urlBaseName . view pathL' $ uri))
 
 
 etagsFile :: FilePath -> FilePath
@@ -242,7 +242,7 @@
     Settings { metaCache } <- lift getSettings
 
        -- for local files, let's short-circuit and ignore access time
-    if | scheme == "file" -> liftE $ download uri' Nothing Nothing cacheDir Nothing True
+    if | scheme == "file" -> liftE $ download uri' Nothing Nothing (fromGHCupPath cacheDir) Nothing True
        | e -> do
           accessTime <- fmap utcTimeToPOSIXSeconds $ liftIO $ getAccessTime json_file
           let sinceLastAccess = utcTimeToPOSIXSeconds currentTime - accessTime
@@ -581,7 +581,7 @@
     True -> downloadCached' dli mfn Nothing
     False -> do
       tmp <- lift withGHCupTmpDir
-      liftE $ download (_dlUri dli) Nothing (Just (_dlHash dli)) tmp mfn False
+      liftE $ download (_dlUri dli) Nothing (Just (_dlHash dli)) (fromGHCupPath tmp) mfn False
 
 
 downloadCached' :: ( MonadReader env m
@@ -599,7 +599,7 @@
                 -> Excepts '[DigestError , DownloadFailed, GPGError] m FilePath
 downloadCached' dli mfn mDestDir = do
   Dirs { cacheDir } <- lift getDirs
-  let destDir = fromMaybe cacheDir mDestDir
+  let destDir = fromMaybe (fromGHCupPath cacheDir) mDestDir
   let fn = fromMaybe ((T.unpack . decUTF8Safe) $ urlBaseName $ view (dlUri % pathL') dli) mfn
   let cachfile = destDir </> fn
   fileExists <- liftIO $ doesFileExist cachfile
diff --git a/lib/GHCup/Download/IOStreams.hs b/lib/GHCup/Download/IOStreams.hs
--- a/lib/GHCup/Download/IOStreams.hs
+++ b/lib/GHCup/Download/IOStreams.hs
@@ -10,7 +10,7 @@
 import           GHCup.Download.Utils
 import           GHCup.Errors
 import           GHCup.Types.JSON               ( )
-import           GHCup.Utils.Prelude
+import           GHCup.Prelude
 
 import           Control.Applicative
 import           Control.Exception.Safe
diff --git a/lib/GHCup/Download/Utils.hs b/lib/GHCup/Download/Utils.hs
--- a/lib/GHCup/Download/Utils.hs
+++ b/lib/GHCup/Download/Utils.hs
@@ -10,7 +10,7 @@
 import           GHCup.Errors
 import           GHCup.Types.Optics
 import           GHCup.Types.JSON               ( )
-import           GHCup.Utils.Prelude
+import           GHCup.Prelude
 
 import           Control.Applicative
 import           Control.Monad
diff --git a/lib/GHCup/Errors.hs b/lib/GHCup/Errors.hs
--- a/lib/GHCup/Errors.hs
+++ b/lib/GHCup/Errors.hs
@@ -105,6 +105,15 @@
   pPrint (CopyError reason) =
     text ("Unable to copy a file. Reason was: " ++ reason)
 
+-- | Unable to merge file trees.
+data MergeFileTreeError = MergeFileTreeError IOException FilePath FilePath
+  deriving Show
+
+instance Pretty MergeFileTreeError where
+  pPrint (MergeFileTreeError e from to) =
+    text "Failed to merge file tree from" <+> text from <+> text "to" <+> text to <+> text "\nexception was:" <+> text (displayException e)
+     <+> text "\n...you may need to delete" <+> text to <+> text "manually. Make sure it's gone."
+
 -- | Unable to find a tag of a tool.
 data TagNotFound = TagNotFound Tag Tool
   deriving Show
@@ -128,10 +137,13 @@
 
 instance Pretty AlreadyInstalled where
   pPrint (AlreadyInstalled tool ver') =
-    pPrint tool <+> text "-" <+> pPrint ver' <+> text "is already installed"
+    (pPrint tool <> text "-" <> pPrint ver') <+> text "is already installed;"
+    <+> text "if you really want to reinstall it, you may want to run 'ghcup install cabal --force" <+> (pPrint ver' <> text "'")
 
+
 -- | The Directory is supposed to be empty, but wasn't.
 data DirNotEmpty = DirNotEmpty {path :: FilePath}
+  deriving Show
 
 instance Pretty DirNotEmpty where
   pPrint (DirNotEmpty path) = do
@@ -146,6 +158,13 @@
   pPrint (NotInstalled tool ver) =
     text "The version" <+> pPrint ver <+> text "of the tool" <+> pPrint tool <+> text "is not installed."
 
+data UninstallFailed = UninstallFailed FilePath [FilePath]
+  deriving Show
+
+instance Pretty UninstallFailed where
+  pPrint (UninstallFailed dir files) =
+    text "The following files survived uninstallation: " <+> pPrint files <+> text "...consider removing" <+> pPrint dir <+> text "manually."
+
 -- | An executable was expected to be in PATH, but was not found.
 data NotFoundInPATH = NotFoundInPATH FilePath
   deriving Show
@@ -292,19 +311,21 @@
   pPrint HadrianNotFound =
     text "Could not find Hadrian build files. Does this GHC version support Hadrian builds?"
 
-data GHCupShadowed = GHCupShadowed
+data ToolShadowed = ToolShadowed
+                       Tool
                        FilePath  -- shadow binary
                        FilePath  -- upgraded binary
                        Version   -- upgraded version
   deriving Show
 
-instance Pretty GHCupShadowed where
-  pPrint (GHCupShadowed sh up _) =
-    text ("ghcup is shadowed by "
+instance Pretty ToolShadowed where
+  pPrint (ToolShadowed tool sh up _) =
+    text (prettyShow tool
+         <> " is shadowed by "
          <> sh
-         <> ". The upgrade will not be in effect, unless you remove "
+         <> ".\nThe upgrade will not be in effect, unless you remove "
          <> sh
-         <> " or make sure "
+         <> "\nor make sure "
          <> takeDirectory up
          <> " comes before "
          <> takeDirectory sh
@@ -325,6 +346,17 @@
       _ -> text "Download failed:" <+> pPrint reason
 
 deriving instance Show DownloadFailed
+
+data InstallSetError = forall xs1 xs2 . (Show (V xs1), Pretty (V xs1), Show (V xs2), Pretty (V xs2)) => InstallSetError (V xs1) (V xs2)
+
+instance Pretty InstallSetError where
+  pPrint (InstallSetError reason1 reason2) =
+     text "Both installation and setting the tool failed. Install error was:"
+      <+> pPrint reason1
+      <+> text "\nSet error was:"
+      <+> pPrint reason2
+
+deriving instance Show InstallSetError
 
 
 -- | A build failed.
diff --git a/lib/GHCup/GHC.hs b/lib/GHCup/GHC.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/GHC.hs
@@ -0,0 +1,1157 @@
+{-# LANGUAGE CPP                   #-}
+{-# LANGUAGE BangPatterns          #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings     #-}
+{-# LANGUAGE QuasiQuotes           #-}
+{-# LANGUAGE TemplateHaskell       #-}
+
+{-|
+Module      : GHCup.GHC
+Description : GHCup installation functions for GHC
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+-}
+module GHCup.GHC where
+
+
+import           GHCup.Download
+import           GHCup.Errors
+import           GHCup.Types
+import           GHCup.Types.JSON               ( )
+import           GHCup.Types.Optics
+import           GHCup.Utils
+import           GHCup.Prelude
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.Process
+import           GHCup.Prelude.String.QQ
+import           GHCup.Prelude.Version.QQ
+import           GHCup.Prelude.MegaParsec
+
+import           Codec.Archive                  ( ArchiveResult )
+import           Control.Applicative
+import           Control.Concurrent             ( threadDelay )
+import           Control.Exception.Safe
+import           Control.Monad
+#if !MIN_VERSION_base(4,13,0)
+import           Control.Monad.Fail             ( MonadFail )
+#endif
+import           Control.Monad.Reader
+import           Control.Monad.Trans.Resource
+                                         hiding ( throwM )
+import           Data.ByteString                ( ByteString )
+import           Data.Either
+import           Data.List
+import           Data.Maybe
+import           Data.List.NonEmpty             ( NonEmpty((:|)) )
+import           Data.String                    ( fromString )
+import           Data.Text                      ( Text )
+import           Data.Time.Clock
+import           Data.Time.Format.ISO8601
+import           Data.Versions                hiding ( patch )
+import           GHC.IO.Exception
+import           Haskus.Utils.Variant.Excepts
+import           Language.Haskell.TH
+import           Language.Haskell.TH.Syntax     ( Quasi(qAddDependentFile) )
+import           Optics
+import           Prelude                 hiding ( abs
+                                                , writeFile
+                                                )
+import           System.Environment
+import           System.FilePath
+import           System.IO.Error
+import           Text.PrettyPrint.HughesPJClass ( prettyShow )
+import           Text.Regex.Posix
+import           URI.ByteString
+
+import qualified Crypto.Hash.SHA256            as SHA256
+import qualified Data.ByteString.Base16        as B16
+import qualified Data.ByteString               as B
+import qualified Data.ByteString.Lazy          as BL
+import qualified Data.Text                     as T
+import qualified Data.Text.IO                  as T
+import qualified Data.Text.Encoding            as E
+import qualified Text.Megaparsec               as MP
+
+
+data GHCVer v = SourceDist v
+              | GitDist GitBranch
+              | RemoteDist URI
+
+
+
+    ---------------------
+    --[ Tool fetching ]--
+    ---------------------
+
+
+
+fetchGHCSrc :: ( MonadFail m
+               , MonadMask m
+               , MonadCatch m
+               , MonadReader env m
+               , HasDirs env
+               , HasSettings env
+               , HasPlatformReq env
+               , HasGHCupInfo env
+               , HasLog env
+               , MonadResource m
+               , MonadIO m
+               , MonadUnliftIO m
+               )
+            => Version
+            -> Maybe FilePath
+            -> Excepts
+                 '[ DigestError
+                  , GPGError
+                  , DownloadFailed
+                  , NoDownload
+                  ]
+                 m
+                 FilePath
+fetchGHCSrc v mfp = do
+  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
+  dlInfo <-
+    preview (ix GHC % ix v % viSourceDL % _Just) dls
+      ?? NoDownload
+  liftE $ downloadCached' dlInfo Nothing mfp
+
+
+
+    -------------------------
+    --[ Tool installation ]--
+    -------------------------
+
+
+-- | Like 'installGHCBin', except takes the 'DownloadInfo' as
+-- argument instead of looking it up from 'GHCupDownloads'.
+installGHCBindist :: ( MonadFail m
+                     , MonadMask m
+                     , MonadCatch m
+                     , MonadReader env m
+                     , HasDirs env
+                     , HasSettings env
+                     , HasPlatformReq env
+                     , HasLog env
+                     , MonadResource m
+                     , MonadIO m
+                     , MonadUnliftIO m
+                     )
+                  => DownloadInfo    -- ^ where/how to download
+                  -> Version         -- ^ the version to install
+                  -> InstallDir
+                  -> Bool            -- ^ Force install
+                  -> [T.Text]        -- ^ additional configure args for bindist
+                  -> Excepts
+                       '[ AlreadyInstalled
+                        , BuildFailed
+                        , DigestError
+                        , GPGError
+                        , DownloadFailed
+                        , NoDownload
+                        , NotInstalled
+                        , UnknownArchive
+                        , TarDirDoesNotExist
+                        , DirNotEmpty
+                        , ArchiveResult
+                        , ProcessError
+                        , UninstallFailed
+                        , MergeFileTreeError
+                        ]
+                       m
+                       ()
+installGHCBindist dlinfo ver installDir forceInstall addConfArgs = do
+  let tver = mkTVer ver
+
+  lift $ logDebug $ "Requested to install GHC with " <> prettyVer ver
+
+  regularGHCInstalled <- lift $ ghcInstalled tver
+
+  if
+    | not forceInstall
+    , regularGHCInstalled
+    , GHCupInternal <- installDir -> do
+        throwE $ AlreadyInstalled GHC ver
+
+    | forceInstall
+    , regularGHCInstalled
+    , GHCupInternal <- installDir -> do
+        lift $ logInfo "Removing the currently installed GHC version first!"
+        liftE $ rmGHCVer tver
+
+    | otherwise -> pure ()
+
+  -- download (or use cached version)
+  dl <- liftE $ downloadCached dlinfo Nothing
+
+
+  toolchainSanityChecks
+
+  case installDir of
+    IsolateDir isoDir -> do                        -- isolated install
+      lift $ logInfo $ "isolated installing GHC to " <> T.pack isoDir
+      liftE $ installPackedGHC dl (view dlSubdir dlinfo) (IsolateDirResolved isoDir) ver forceInstall addConfArgs
+    GHCupInternal -> do                            -- regular install
+      -- prepare paths
+      ghcdir <- lift $ ghcupGHCDir tver
+
+      liftE $ installPackedGHC dl (view dlSubdir dlinfo) (GHCupDir ghcdir) ver forceInstall addConfArgs
+
+      -- make symlinks & stuff when regular install,
+      liftE $ postGHCInstall tver
+
+ where
+  toolchainSanityChecks = do
+    r <- forM ["CC", "LD"] (liftIO . lookupEnv)
+    case catMaybes r of
+      [] -> pure ()
+      _ -> do
+        lift $ logWarn $ "CC/LD environment variable is set. This will change the compiler/linker"
+         <> "\n" <> "GHC uses internally and can cause defunct GHC in some cases (e.g. in Anaconda"
+         <> "\n" <> "environments). If you encounter problems, unset CC and LD and reinstall."
+
+
+-- | Install a packed GHC distribution. This only deals with unpacking and the GHC
+-- build system and nothing else.
+installPackedGHC :: ( MonadMask m
+                    , MonadCatch m
+                    , MonadReader env m
+                    , HasDirs env
+                    , HasPlatformReq env
+                    , HasSettings env
+                    , MonadThrow m
+                    , HasLog env
+                    , MonadIO m
+                    , MonadUnliftIO m
+                    , MonadFail m
+                    , MonadResource m
+                    )
+                 => FilePath          -- ^ Path to the packed GHC bindist
+                 -> Maybe TarDir      -- ^ Subdir of the archive
+                 -> InstallDirResolved
+                 -> Version           -- ^ The GHC version
+                 -> Bool              -- ^ Force install
+                 -> [T.Text]          -- ^ additional configure args for bindist
+                 -> Excepts
+                      '[ BuildFailed
+                       , UnknownArchive
+                       , TarDirDoesNotExist
+                       , DirNotEmpty
+                       , ArchiveResult
+                       , ProcessError
+                       , MergeFileTreeError
+                       ] m ()
+installPackedGHC dl msubdir inst ver forceInstall addConfArgs = do
+  PlatformRequest {..} <- lift getPlatformReq
+
+  unless forceInstall
+    (liftE $ installDestSanityCheck inst)
+
+  -- unpack
+  tmpUnpack <- lift mkGhcupTmpDir
+  liftE $ cleanUpOnError tmpUnpack (unpackToDir (fromGHCupPath tmpUnpack) dl)
+  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpUnpack)
+
+  -- the subdir of the archive where we do the work
+  workdir <- maybe (pure tmpUnpack)
+                   (liftE . intoSubdir tmpUnpack)
+                   msubdir
+
+  liftE $ runBuildAction tmpUnpack
+                         (installUnpackedGHC workdir inst ver forceInstall addConfArgs)
+
+
+-- | Install an unpacked GHC distribution. This only deals with the GHC
+-- build system and nothing else.
+installUnpackedGHC :: ( MonadReader env m
+                      , HasPlatformReq env
+                      , HasDirs env
+                      , HasSettings env
+                      , MonadThrow m
+                      , HasLog env
+                      , MonadIO m
+                      , MonadUnliftIO m
+                      , MonadMask m
+                      , MonadResource m
+                      , MonadFail m
+                      )
+                   => GHCupPath           -- ^ Path to the unpacked GHC bindist (where the configure script resides)
+                   -> InstallDirResolved  -- ^ Path to install to
+                   -> Version             -- ^ The GHC version
+                   -> Bool                -- ^ Force install
+                   -> [T.Text]          -- ^ additional configure args for bindist
+                   -> Excepts '[ProcessError, MergeFileTreeError] m ()
+installUnpackedGHC path inst ver forceInstall addConfArgs
+  | isWindows = do
+      lift $ logInfo "Installing GHC (this may take a while)"
+      -- Windows bindists are relocatable and don't need
+      -- to run configure.
+      -- We also must make sure to preserve mtime to not confuse ghc-pkg.
+      liftE $ mergeFileTree path inst GHC (mkTVer ver) $ \source dest -> do
+        mtime <- liftIO $ ifM (pathIsSymbolicLink source) (pure Nothing) (Just <$> getModificationTime source)
+        when forceInstall $ hideError doesNotExistErrorType $ hideError InappropriateType $ recycleFile dest
+        liftIO $ moveFilePortable source dest
+        forM_ mtime $ liftIO . setModificationTime dest
+  | otherwise = do
+      PlatformRequest {..} <- lift getPlatformReq
+
+      let ldOverride
+           | ver >= [vver|8.2.2|]
+           , _rPlatform `elem` [Linux Alpine, Darwin]
+           = ["--disable-ld-override"]
+           | otherwise
+           = []
+
+      lift $ logInfo "Installing GHC (this may take a while)"
+      lEM $ execLogged "sh"
+                       ("./configure" : ("--prefix=" <> fromInstallDir inst)
+                        : (ldOverride <> (T.unpack <$> addConfArgs))
+                       )
+                       (Just $ fromGHCupPath path)
+                       "ghc-configure"
+                       Nothing
+      tmpInstallDest <- lift withGHCupTmpDir
+      lEM $ make ["DESTDIR=" <> fromGHCupPath tmpInstallDest, "install"] (Just $ fromGHCupPath path)
+      liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpInstallDest)
+      liftE $ mergeFileTree (tmpInstallDest `appendGHCupPath` dropDrive (fromInstallDir inst))
+        inst
+        GHC
+        (mkTVer ver)
+        (\f t -> liftIO $ do
+            mtime <- ifM (pathIsSymbolicLink f) (pure Nothing) (Just <$> getModificationTime f)
+            install f t (not forceInstall)
+            forM_ mtime $ setModificationTime t)
+
+      pure ()
+
+
+-- | Installs GHC into @~\/.ghcup\/ghc/\<ver\>@ and places the
+-- following symlinks in @~\/.ghcup\/bin@:
+--
+--   * @ghc-x.y.z -> ..\/ghc\/x.y.z\/bin/ghc@
+--   * @ghc-x.y   -> ..\/ghc\/x.y.z\/bin/ghc@ (if x.y.z is the latest x.y version)
+installGHCBin :: ( MonadFail m
+                 , MonadMask m
+                 , MonadCatch m
+                 , MonadReader env m
+                 , HasPlatformReq env
+                 , HasGHCupInfo env
+                 , HasDirs env
+                 , HasSettings env
+                 , HasLog env
+                 , MonadResource m
+                 , MonadIO m
+                 , MonadUnliftIO m
+                 )
+              => Version         -- ^ the version to install
+              -> InstallDir
+              -> Bool            -- ^ force install
+              -> [T.Text]        -- ^ additional configure args for bindist
+              -> Excepts
+                   '[ AlreadyInstalled
+                    , BuildFailed
+                    , DigestError
+                    , GPGError
+                    , DownloadFailed
+                    , NoDownload
+                    , NotInstalled
+                    , UnknownArchive
+                    , TarDirDoesNotExist
+                    , DirNotEmpty
+                    , ArchiveResult
+                    , ProcessError
+                    , UninstallFailed
+                    , MergeFileTreeError
+                    ]
+                   m
+                   ()
+installGHCBin ver installDir forceInstall addConfArgs = do
+  dlinfo <- liftE $ getDownloadInfo GHC ver
+  liftE $ installGHCBindist dlinfo ver installDir forceInstall addConfArgs
+
+
+
+
+
+    ---------------
+    --[ Set GHC ]--
+    ---------------
+
+
+
+-- | Set GHC symlinks in @~\/.ghcup\/bin@ for the requested GHC version. The behavior depends
+-- on `SetGHC`:
+--
+--   * SetGHCOnly: @~\/.ghcup\/bin\/ghc -> ~\/.ghcup\/ghc\/\<ver\>\/bin\/ghc@
+--   * SetGHC_XY: @~\/.ghcup\/bin\/ghc-X.Y -> ~\/.ghcup\/ghc\/\<ver\>\/bin\/ghc@
+--   * SetGHC_XYZ: @~\/.ghcup\/bin\/ghc-\<ver\> -> ~\/.ghcup\/ghc\/\<ver\>\/bin\/ghc@
+--
+-- Additionally creates a @~\/.ghcup\/share -> ~\/.ghcup\/ghc\/\<ver\>\/share symlink@
+-- for 'SetGHCOnly' constructor.
+setGHC :: ( MonadReader env m
+          , HasDirs env
+          , HasLog env
+          , MonadThrow m
+          , MonadFail m
+          , MonadIO m
+          , MonadCatch m
+          , MonadMask m
+          , MonadUnliftIO m
+          )
+       => GHCTargetVersion
+       -> SetGHC
+       -> Maybe FilePath  -- if set, signals that we're not operating in ~/.ghcup/bin
+                          -- and don't want mess with other versions
+       -> Excepts '[NotInstalled] m GHCTargetVersion
+setGHC ver sghc mBinDir = do
+  let verS = T.unpack $ prettyVer (_tvVersion ver)
+  ghcdir                        <- lift $ ghcupGHCDir ver
+
+  whenM (lift $ not <$> ghcInstalled ver) (throwE (NotInstalled GHC ver))
+
+  -- symlink destination
+  binDir <- case mBinDir of
+    Just x -> pure x
+    Nothing -> do
+      Dirs {binDir = f} <- lift getDirs
+      pure f
+
+  -- first delete the old symlinks (this fixes compatibility issues
+  -- with old ghcup)
+  when (isNothing mBinDir) $
+    case sghc of
+      SetGHCOnly -> liftE $ rmPlainGHC (_tvTarget ver)
+      SetGHC_XY  -> liftE $ rmMajorGHCSymlinks ver
+      SetGHC_XYZ -> liftE $ rmMinorGHCSymlinks ver
+
+  -- for ghc tools (ghc, ghci, haddock, ...)
+  verfiles <- ghcToolFiles ver
+  forM_ verfiles $ \file -> do
+    mTargetFile <- case sghc of
+      SetGHCOnly -> pure $ Just file
+      SetGHC_XY  -> do
+        handle
+            (\(e :: ParseError) -> lift $ logWarn (T.pack $ displayException e) >> pure Nothing)
+          $ do
+            (mj, mi) <- getMajorMinorV (_tvVersion ver)
+            let major' = intToText mj <> "." <> intToText mi
+            pure $ Just (file <> "-" <> T.unpack major')
+      SetGHC_XYZ ->
+        pure $ Just (file <> "-" <> verS)
+
+    -- create symlink
+    forM_ mTargetFile $ \targetFile -> do
+      bindir <- ghcInternalBinDir ver
+      let fullF = binDir </> targetFile  <> exeExt
+          fileWithExt = bindir </> file <> exeExt
+      destL <- binarySymLinkDestination binDir fileWithExt
+      lift $ createLink destL fullF
+
+      when (targetFile == "ghc") $
+        liftIO (isShadowed fullF) >>= \case
+          Nothing -> pure ()
+          Just pa -> lift $ logWarn $ T.pack $ prettyShow (ToolShadowed GHC pa fullF (_tvVersion ver))
+
+  when (isNothing mBinDir) $ do
+    -- create symlink for share dir
+    when (isNothing . _tvTarget $ ver) $ lift $ symlinkShareDir (fromGHCupPath ghcdir) verS
+
+    when (sghc == SetGHCOnly) $ lift warnAboutHlsCompatibility
+
+  pure ver
+
+ where
+
+  symlinkShareDir :: ( MonadReader env m
+                     , HasDirs env
+                     , MonadIO m
+                     , HasLog env
+                     , MonadCatch m
+                     , MonadMask m
+                     )
+                  => FilePath
+                  -> String
+                  -> m ()
+  symlinkShareDir ghcdir ver' = do
+    Dirs {..} <- getDirs
+    let destdir = fromGHCupPath baseDir
+    case sghc of
+      SetGHCOnly -> do
+        let sharedir     = "share"
+        let fullsharedir = ghcdir </> sharedir
+        logDebug $ "Checking for sharedir existence: " <> T.pack fullsharedir
+        whenM (liftIO $ doesDirectoryExist fullsharedir) $ do
+          let fullF   = destdir </> sharedir
+          let targetF = "." </> "ghc" </> ver' </> sharedir
+          logDebug $ "rm -f " <> T.pack fullF
+          hideError doesNotExistErrorType $ rmDirectoryLink fullF
+          logDebug $ "ln -s " <> T.pack targetF <> " " <> T.pack fullF
+
+          if isWindows
+          then liftIO
+                 -- On windows we need to be more permissive
+                 -- in case symlinks can't be created, be just
+                 -- give up here. This symlink isn't strictly necessary.
+                 $ hideError permissionErrorType
+                 $ hideError illegalOperationErrorType
+                 $ createDirectoryLink targetF fullF
+          else liftIO
+                 $ createDirectoryLink targetF fullF
+      _ -> pure ()
+
+unsetGHC :: ( MonadReader env m
+            , HasDirs env
+            , HasLog env
+            , MonadThrow m
+            , MonadFail m
+            , MonadIO m
+            , MonadMask m
+            )
+         => Maybe Text
+         -> Excepts '[NotInstalled] m ()
+unsetGHC = rmPlainGHC
+
+
+
+
+
+    --------------
+    --[ GHC rm ]--
+    --------------
+
+
+-- | Delete a ghc version and all its symlinks.
+--
+-- This may leave GHCup without a "set" version.
+-- Will try to fix the ghc-x.y symlink after removal (e.g. to an
+-- older version).
+rmGHCVer :: ( MonadReader env m
+            , HasDirs env
+            , MonadThrow m
+            , HasLog env
+            , MonadIO m
+            , MonadFail m
+            , MonadCatch m
+            , MonadMask m
+            , MonadUnliftIO m
+            )
+         => GHCTargetVersion
+         -> Excepts '[NotInstalled, UninstallFailed] m ()
+rmGHCVer ver = do
+  isSetGHC <- lift $ fmap (== Just ver) $ ghcSet (_tvTarget ver)
+
+  whenM (lift $ fmap not $ ghcInstalled ver) (throwE (NotInstalled GHC ver))
+
+  -- this isn't atomic, order matters
+  when isSetGHC $ do
+    lift $ logInfo "Removing ghc symlinks"
+    liftE $ rmPlainGHC (_tvTarget ver)
+
+  lift $ logInfo "Removing ghc-x.y.z symlinks"
+  liftE $ rmMinorGHCSymlinks ver
+
+  lift $ logInfo "Removing/rewiring ghc-x.y symlinks"
+  -- first remove
+  handle (\(_ :: ParseError) -> pure ()) $ liftE $ rmMajorGHCSymlinks ver
+  -- then fix them (e.g. with an earlier version)
+
+  dir' <- lift $ ghcupGHCDir ver
+  let dir = fromGHCupPath dir'
+  lift (getInstalledFiles GHC ver) >>= \case
+    Just files -> do
+      lift $ logInfo $ "Removing files safely from: " <> T.pack dir
+      forM_ files (lift . hideError NoSuchThing . recycleFile . (\f -> dir </> dropDrive f))
+      removeEmptyDirsRecursive dir
+      survivors <- liftIO $ hideErrorDef [doesNotExistErrorType] [] $ listDirectory dir
+      f <- recordedInstallationFile GHC ver
+      lift $ recycleFile f
+      when (not (null survivors)) $ throwE $ UninstallFailed dir survivors
+    Nothing -> do
+      isDir <- liftIO $ doesDirectoryExist dir
+      isSyml <- liftIO $ handleIO (\_ -> pure False) $ pathIsSymbolicLink dir
+      when (isDir && not isSyml) $ do
+        lift $ logInfo $ "Removing legacy directory recursively: " <> T.pack dir
+        recyclePathForcibly dir'
+
+  v' <-
+    handle
+      (\(e :: ParseError) -> lift $ logWarn (T.pack $ displayException e) >> pure Nothing)
+    $ fmap Just
+    $ getMajorMinorV (_tvVersion ver)
+  forM_ v' $ \(mj, mi) -> lift (getGHCForPVP (PVP (fromIntegral mj :| [fromIntegral mi])) (_tvTarget ver))
+    >>= mapM_ (\v -> liftE $ setGHC v SetGHC_XY Nothing)
+
+  Dirs {..} <- lift getDirs
+
+  lift $ hideError doesNotExistErrorType $ rmDirectoryLink (fromGHCupPath baseDir </> "share")
+
+
+
+
+    ---------------
+    --[ Compile ]--
+    ---------------
+
+
+-- | Compile a GHC from source. This behaves wrt symlinks and installation
+-- the same as 'installGHCBin'.
+compileGHC :: ( MonadMask m
+              , MonadReader env m
+              , HasDirs env
+              , HasPlatformReq env
+              , HasGHCupInfo env
+              , HasSettings env
+              , MonadThrow m
+              , MonadResource m
+              , HasLog env
+              , MonadIO m
+              , MonadUnliftIO m
+              , MonadFail m
+              )
+           => GHCVer GHCTargetVersion
+           -> Maybe Version            -- ^ overwrite version
+           -> Either Version FilePath  -- ^ version to bootstrap with
+           -> Maybe Int                -- ^ jobs
+           -> Maybe FilePath           -- ^ build config
+           -> Maybe (Either FilePath [URI])  -- ^ patches
+           -> [Text]                   -- ^ additional args to ./configure
+           -> Maybe String             -- ^ build flavour
+           -> Bool
+           -> InstallDir
+           -> Excepts
+                '[ AlreadyInstalled
+                 , BuildFailed
+                 , DigestError
+                 , GPGError
+                 , DownloadFailed
+                 , GHCupSetError
+                 , NoDownload
+                 , NotFoundInPATH
+                 , PatchFailed
+                 , UnknownArchive
+                 , TarDirDoesNotExist
+                 , NotInstalled
+                 , DirNotEmpty
+                 , ArchiveResult
+                 , FileDoesNotExistError
+                 , HadrianNotFound
+                 , InvalidBuildConfig
+                 , ProcessError
+                 , CopyError
+                 , BuildFailed
+                 , UninstallFailed
+                 , MergeFileTreeError
+                 ]
+                m
+                GHCTargetVersion
+compileGHC targetGhc ov bstrap jobs mbuildConfig patches aargs buildFlavour hadrian installDir
+  = do
+    PlatformRequest { .. } <- lift getPlatformReq
+    GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
+
+    (workdir, tmpUnpack, tver) <- case targetGhc of
+      -- unpack from version tarball
+      SourceDist tver -> do
+        lift $ logDebug $ "Requested to compile: " <> tVerToText tver <> " with " <> either prettyVer T.pack bstrap
+
+        -- download source tarball
+        dlInfo <-
+          preview (ix GHC % ix (tver ^. tvVersion) % viSourceDL % _Just) dls
+            ?? NoDownload
+        dl <- liftE $ downloadCached dlInfo Nothing
+
+        -- unpack
+        tmpUnpack <- lift mkGhcupTmpDir
+        liftE $ cleanUpOnError tmpUnpack (unpackToDir (fromGHCupPath tmpUnpack) dl)
+        liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform $ fromGHCupPath tmpUnpack
+
+        workdir <- maybe (pure tmpUnpack)
+                         (liftE . intoSubdir tmpUnpack)
+                         (view dlSubdir dlInfo)
+        liftE $ applyAnyPatch patches (fromGHCupPath workdir)
+
+        pure (workdir, tmpUnpack, tver)
+
+      RemoteDist uri -> do
+        lift $ logDebug $ "Requested to compile (from uri): " <> T.pack (show uri)
+
+        -- download source tarball
+        tmpDownload <- lift withGHCupTmpDir
+        tmpUnpack <- lift mkGhcupTmpDir
+        tar <- liftE $ download uri Nothing Nothing (fromGHCupPath tmpDownload) Nothing False
+        (bf, tver) <- liftE $ cleanUpOnError @'[UnknownArchive, ArchiveResult, ProcessError] tmpUnpack $ do
+          liftE $ unpackToDir (fromGHCupPath tmpUnpack) tar
+          let regex = [s|^(.*/)*boot$|] :: B.ByteString
+          [bootFile] <- liftIO $ findFilesDeep
+            tmpUnpack
+            (makeRegexOpts compExtended
+                           execBlank
+                           regex
+            )
+          tver <- liftE $ getGHCVer (appendGHCupPath tmpUnpack (takeDirectory bootFile))
+          pure (bootFile, tver)
+
+        let workdir = appendGHCupPath tmpUnpack (takeDirectory bf)
+
+        pure (workdir, tmpUnpack, mkTVer tver)
+
+      -- clone from git
+      GitDist GitBranch{..} -> do
+        tmpUnpack <- lift mkGhcupTmpDir
+        let git args = execLogged "git" ("--no-pager":args) (Just $ fromGHCupPath tmpUnpack) "git" Nothing
+        tver <- reThrowAll @_ @'[PatchFailed, ProcessError, NotFoundInPATH, DigestError, DownloadFailed, GPGError] DownloadFailed $ do
+          let rep = fromMaybe "https://gitlab.haskell.org/ghc/ghc.git" repo
+          lift $ logInfo $ "Fetching git repo " <> T.pack rep <> " at ref " <> T.pack ref <> " (this may take a while)"
+          lEM $ git [ "init" ]
+          lEM $ git [ "remote"
+                    , "add"
+                    , "origin"
+                    , fromString rep ]
+
+          -- figure out if we can do a shallow clone
+          remoteBranches <- catchE @ProcessError @'[PatchFailed, ProcessError, NotFoundInPATH, DigestError, DownloadFailed, GPGError] @'[PatchFailed, NotFoundInPATH, DigestError, DownloadFailed, GPGError] (\(_ :: ProcessError) -> pure [])
+              $ fmap processBranches $ gitOut ["ls-remote", "--heads", "origin"] (fromGHCupPath tmpUnpack)
+          let shallow_clone
+                | isCommitHash ref                     = True
+                | fromString ref `elem` remoteBranches = True
+                | otherwise                            = False
+          lift $ logDebug $ "Shallow clone: " <> T.pack (show shallow_clone)
+
+          -- fetch
+          let fetch_args
+                | shallow_clone = ["fetch", "--depth", "1", "--quiet", "origin", fromString ref]
+                | otherwise     = ["fetch", "--tags",       "--quiet", "origin"                ]
+          lEM $ git fetch_args
+
+          -- initial checkout
+          lEM $ git [ "checkout", fromString ref ]
+
+          -- gather some info
+          git_describe <- if shallow_clone
+                          then pure Nothing
+                          else fmap Just $ liftE $ gitOut ["describe", "--tags"] (fromGHCupPath tmpUnpack)
+          chash <- liftE $ gitOut ["rev-parse", "HEAD" ] (fromGHCupPath tmpUnpack)
+
+          -- clone submodules
+          lEM $ git [ "submodule", "update", "--init", "--depth", "1" ]
+
+          -- apply patches
+          liftE $ applyAnyPatch patches (fromGHCupPath tmpUnpack)
+
+          -- bootstrap
+          tver <- liftE $ getGHCVer tmpUnpack
+          liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpUnpack)
+          lift $ logInfo $ "Examining git ref " <> T.pack ref <> "\n  " <>
+                           "GHC version (from Makefile): " <> prettyVer tver <>
+                           (if not shallow_clone then "\n  " <> "'git describe' output: " <> fromJust git_describe else mempty) <>
+                           (if isCommitHash ref then mempty else "\n  " <> "commit hash: " <> chash)
+          liftIO $ threadDelay 5000000 -- give the user a sec to intervene
+
+          pure tver
+
+        pure (tmpUnpack, tmpUnpack, GHCTargetVersion Nothing tver)
+    -- the version that's installed may differ from the
+    -- compiled version, so the user can overwrite it
+    let installVer = maybe tver (\ov' -> tver { _tvVersion = ov' }) ov
+
+    alreadyInstalled <- lift $ ghcInstalled installVer
+    alreadySet <- fmap (== Just installVer) $ lift $ ghcSet (_tvTarget installVer)
+
+    when alreadyInstalled $ do
+      case installDir of
+        IsolateDir isoDir ->
+          lift $ logWarn $ "GHC " <> T.pack (prettyShow installVer) <> " already installed. Isolate installing to " <> T.pack isoDir
+        GHCupInternal ->
+          lift $ logWarn $ "GHC " <> T.pack (prettyShow installVer) <> " already installed. Will overwrite existing version."
+      lift $ logWarn
+        "...waiting for 10 seconds before continuing, you can still abort..."
+      liftIO $ threadDelay 10000000 -- give the user a sec to intervene
+
+    ghcdir <- case installDir of
+      IsolateDir isoDir -> pure $ IsolateDirResolved isoDir
+      GHCupInternal -> GHCupDir <$> lift (ghcupGHCDir installVer)
+
+    (mBindist, bmk) <- liftE $ runBuildAction
+      tmpUnpack
+      (do
+        b <- if hadrian
+             then compileHadrianBindist tver (fromGHCupPath workdir) ghcdir
+             else compileMakeBindist tver (fromGHCupPath workdir) ghcdir
+        bmk <- liftIO $ handleIO (\_ -> pure "") $ B.readFile (build_mk $ fromGHCupPath workdir)
+        pure (b, bmk)
+      )
+
+    case installDir of
+      GHCupInternal ->
+        -- only remove old ghc in regular installs
+        when alreadyInstalled $ do
+          lift $ logInfo "Deleting existing installation"
+          liftE $ rmGHCVer installVer
+
+      _ -> pure ()
+
+    forM_ mBindist $ \bindist -> do
+      liftE $ installPackedGHC bindist
+                               (Just $ RegexDir "ghc-.*")
+                               ghcdir
+                               (installVer ^. tvVersion)
+                               False       -- not a force install, since we already overwrite when compiling.
+                               []
+
+    liftIO $ B.writeFile (fromInstallDir ghcdir </> ghcUpSrcBuiltFile) bmk
+
+    case installDir of
+      -- set and make symlinks for regular (non-isolated) installs
+      GHCupInternal -> do
+        reThrowAll GHCupSetError $ postGHCInstall installVer
+        -- restore
+        when alreadySet $ liftE $ void $ setGHC installVer SetGHCOnly Nothing
+
+      _ -> pure ()
+
+    pure installVer
+
+ where
+  getGHCVer :: ( MonadReader env m
+               , HasSettings env
+               , HasDirs env
+               , HasLog env
+               , MonadIO m
+               , MonadThrow m
+               )
+            => GHCupPath
+            -> Excepts '[ProcessError] m Version
+  getGHCVer tmpUnpack = do
+    lEM $ execWithGhcEnv "python3" ["./boot"] (Just $ fromGHCupPath tmpUnpack) "ghc-bootstrap"
+    lEM $ execWithGhcEnv "sh" ["./configure"] (Just $ fromGHCupPath tmpUnpack) "ghc-bootstrap"
+    CapturedProcess {..} <- lift $ makeOut
+      ["show!", "--quiet", "VALUE=ProjectVersion" ] (Just $ fromGHCupPath tmpUnpack)
+    case _exitCode of
+      ExitSuccess -> throwEither . MP.parse ghcProjectVersion "" . T.pack . stripNewlineEnd . T.unpack . decUTF8Safe' $ _stdOut
+      ExitFailure c -> throwE $ NonZeroExit c "make" ["show!", "--quiet", "VALUE=ProjectVersion" ]
+
+  defaultConf =
+    let cross_mk = $(LitE . StringL <$> (qAddDependentFile "data/build_mk/cross" >> runIO (readFile "data/build_mk/cross")))
+        default_mk = $(LitE . StringL <$> (qAddDependentFile "data/build_mk/default" >> runIO (readFile "data/build_mk/default")))
+    in case targetGhc of
+         SourceDist (GHCTargetVersion (Just _) _) -> cross_mk
+         _ -> default_mk
+
+  compileHadrianBindist :: ( MonadReader env m
+                           , HasDirs env
+                           , HasSettings env
+                           , HasPlatformReq env
+                           , MonadThrow m
+                           , MonadCatch m
+                           , HasLog env
+                           , MonadIO m
+                           , MonadFail m
+                           )
+                        => GHCTargetVersion
+                        -> FilePath
+                        -> InstallDirResolved
+                        -> Excepts
+                             '[ FileDoesNotExistError
+                              , HadrianNotFound
+                              , InvalidBuildConfig
+                              , PatchFailed
+                              , ProcessError
+                              , NotFoundInPATH
+                              , CopyError]
+                             m
+                             (Maybe FilePath)  -- ^ output path of bindist, None for cross
+  compileHadrianBindist tver workdir ghcdir = do
+    lEM $ execWithGhcEnv "python3" ["./boot"] (Just workdir) "ghc-bootstrap"
+
+    liftE $ configureBindist tver workdir ghcdir
+
+    lift $ logInfo "Building (this may take a while)..."
+    hadrian_build <- liftE $ findHadrianFile workdir
+    lEM $ execWithGhcEnv hadrian_build
+                          ( maybe [] (\j  -> ["-j" <> show j]         ) jobs
+                         ++ maybe [] (\bf -> ["--flavour=" <> bf]) buildFlavour
+                         ++ ["binary-dist"]
+                          )
+                          (Just workdir) "ghc-make"
+    [tar] <- liftIO $ findFiles
+      (workdir </> "_build" </> "bindist")
+      (makeRegexOpts compExtended
+                     execBlank
+                     ([s|^ghc-.*\.tar\..*$|] :: ByteString)
+      )
+    liftE $ fmap Just $ copyBindist tver tar (workdir </> "_build" </> "bindist")
+
+  findHadrianFile :: (MonadIO m)
+                  => FilePath
+                  -> Excepts
+                       '[HadrianNotFound]
+                       m
+                       FilePath
+  findHadrianFile workdir = do
+    let possible_files = if isWindows
+                         then ((workdir </> "hadrian") </>) <$> ["build.bat"]
+                         else ((workdir </> "hadrian") </>) <$> ["build", "build.sh"]
+    exsists <- forM possible_files (\f -> liftIO (doesFileExist f) <&> (,f))
+    case filter fst exsists of
+      [] -> throwE HadrianNotFound
+      ((_, x):_) -> pure x
+
+  compileMakeBindist :: ( MonadReader env m
+                        , HasDirs env
+                        , HasSettings env
+                        , HasPlatformReq env
+                        , MonadThrow m
+                        , MonadCatch m
+                        , HasLog env
+                        , MonadIO m
+                        , MonadFail m
+                        )
+                     => GHCTargetVersion
+                     -> FilePath
+                     -> InstallDirResolved
+                     -> Excepts
+                          '[ FileDoesNotExistError
+                           , HadrianNotFound
+                           , InvalidBuildConfig
+                           , PatchFailed
+                           , ProcessError
+                           , NotFoundInPATH
+                           , CopyError]
+                          m
+                       (Maybe FilePath)  -- ^ output path of bindist, None for cross
+  compileMakeBindist tver workdir ghcdir = do
+    liftE $ configureBindist tver workdir ghcdir
+
+    case mbuildConfig of
+      Just bc -> liftIOException
+        doesNotExistErrorType
+        (FileDoesNotExistError bc)
+        (liftIO $ copyFile bc (build_mk workdir) False)
+      Nothing ->
+        liftIO $ T.writeFile (build_mk workdir) (addBuildFlavourToConf defaultConf)
+
+    liftE $ checkBuildConfig (build_mk workdir)
+
+    lift $ logInfo "Building (this may take a while)..."
+    lEM $ make (maybe [] (\j -> ["-j" <> fS (show j)]) jobs) (Just workdir)
+
+    if | isCross tver -> do
+          lift $ logInfo "Installing cross toolchain..."
+          lEM $ make ["install"] (Just workdir)
+          pure Nothing
+       | otherwise -> do
+          lift $ logInfo "Creating bindist..."
+          lEM $ make ["binary-dist"] (Just workdir)
+          [tar] <- liftIO $ findFiles
+            workdir
+            (makeRegexOpts compExtended
+                           execBlank
+                           ([s|^ghc-.*\.tar\..*$|] :: ByteString)
+            )
+          liftE $ fmap Just $ copyBindist tver tar workdir
+
+  build_mk workdir = workdir </> "mk" </> "build.mk"
+
+  copyBindist :: ( MonadReader env m
+                 , HasDirs env
+                 , HasSettings env
+                 , HasPlatformReq env
+                 , MonadIO m
+                 , MonadThrow m
+                 , MonadCatch m
+                 , HasLog env
+                 )
+              => GHCTargetVersion
+              -> FilePath           -- ^ tar file
+              -> FilePath           -- ^ workdir
+              -> Excepts
+                   '[CopyError]
+                   m
+                   FilePath
+  copyBindist tver tar workdir = do
+    Dirs {..} <- lift getDirs
+    pfreq <- lift getPlatformReq
+    c       <- liftIO $ BL.readFile (workdir </> tar)
+    cDigest <-
+      fmap (T.take 8)
+      . lift
+      . throwEither
+      . E.decodeUtf8'
+      . B16.encode
+      . SHA256.hashlazy
+      $ c
+    cTime <- liftIO getCurrentTime
+    let tarName = makeValid ("ghc-"
+                            <> T.unpack (tVerToText tver)
+                            <> "-"
+                            <> pfReqToString pfreq
+                            <> "-"
+                            <> iso8601Show cTime
+                            <> "-"
+                            <> T.unpack cDigest
+                            <> ".tar"
+                            <> takeExtension tar)
+    let tarPath = fromGHCupPath cacheDir </> tarName
+    copyFileE (workdir </> tar) tarPath False
+    lift $ logInfo $ "Copied bindist to " <> T.pack tarPath
+    pure tarPath
+
+  checkBuildConfig :: (MonadReader env m, MonadCatch m, MonadIO m, HasLog env)
+                   => FilePath
+                   -> Excepts
+                        '[FileDoesNotExistError, InvalidBuildConfig]
+                        m
+                        ()
+  checkBuildConfig bc = do
+    c <- liftIOException
+           doesNotExistErrorType
+           (FileDoesNotExistError bc)
+           (liftIO $ B.readFile bc)
+    let lines' = fmap T.strip . T.lines $ decUTF8Safe c
+
+   -- for cross, we need Stage1Only
+    case targetGhc of
+      SourceDist (GHCTargetVersion (Just _) _) -> when ("Stage1Only = YES" `notElem` lines') $ throwE
+        (InvalidBuildConfig
+          [s|Cross compiling needs to be a Stage1 build, add "Stage1Only = YES" to your config!|]
+        )
+      _ -> pure ()
+
+    forM_ buildFlavour $ \bf ->
+      when (T.pack ("BuildFlavour = " <> bf) `notElem` lines') $ do
+        lift $ logWarn $ "Customly specified build config overwrites --flavour=" <> T.pack bf <> " switch! Waiting 5 seconds..."
+        liftIO $ threadDelay 5000000
+
+  addBuildFlavourToConf bc = case buildFlavour of
+    Just bf -> "BuildFlavour = " <> T.pack bf <> "\n" <> bc
+    Nothing -> bc
+
+  isCross :: GHCTargetVersion -> Bool
+  isCross = isJust . _tvTarget
+
+
+  configureBindist :: ( MonadReader env m
+                      , HasDirs env
+                      , HasSettings env
+                      , HasPlatformReq env
+                      , MonadThrow m
+                      , MonadCatch m
+                      , HasLog env
+                      , MonadIO m
+                      , MonadFail m
+                      )
+                   => GHCTargetVersion
+                   -> FilePath
+                   -> InstallDirResolved
+                   -> Excepts
+                        '[ FileDoesNotExistError
+                         , InvalidBuildConfig
+                         , PatchFailed
+                         , ProcessError
+                         , NotFoundInPATH
+                         , CopyError
+                         ]
+                        m
+                        ()
+  configureBindist tver workdir (fromInstallDir -> ghcdir) = do
+    lift $ logInfo [s|configuring build|]
+
+    if | _tvVersion tver >= [vver|8.8.0|] -> do
+          lEM $ execWithGhcEnv
+            "sh"
+            ("./configure" :  maybe mempty
+                      (\x -> ["--target=" <> T.unpack x])
+                      (_tvTarget tver)
+            ++ ["--prefix=" <> ghcdir]
+            ++ (if isWindows then ["--enable-tarballs-autodownload"] else [])
+            ++ fmap T.unpack aargs
+            )
+            (Just workdir)
+            "ghc-conf"
+       | otherwise -> do
+        lEM $ execLogged
+          "sh"
+          (  [ "./configure", "--with-ghc=" <> either id id bghc
+             ]
+          ++ maybe mempty
+                   (\x -> ["--target=" <> T.unpack x])
+                   (_tvTarget tver)
+          ++ ["--prefix=" <> ghcdir]
+          ++ (if isWindows then ["--enable-tarballs-autodownload"] else [])
+          ++ fmap T.unpack aargs
+          )
+          (Just workdir)
+          "ghc-conf"
+          Nothing
+    pure ()
+
+  execWithGhcEnv :: ( MonadReader env m
+                    , HasSettings env
+                    , HasDirs env
+                    , HasLog env
+                    , MonadIO m
+                    , MonadThrow m)
+                 => FilePath         -- ^ thing to execute
+                 -> [String]         -- ^ args for the thing
+                 -> Maybe FilePath   -- ^ optionally chdir into this
+                 -> FilePath         -- ^ log filename (opened in append mode)
+                 -> m (Either ProcessError ())
+  execWithGhcEnv fp args dir logf = do
+    env <- ghcEnv
+    execLogged fp args dir logf (Just env)
+
+  bghc = case bstrap of
+           Right g    -> Right g
+           Left  bver -> Left ("ghc-" <> (T.unpack . prettyVer $ bver) <> exeExt)
+
+  ghcEnv :: (MonadThrow m, MonadIO m) => m [(String, String)]
+  ghcEnv = do
+    cEnv <- liftIO getEnvironment
+    bghcPath <- case bghc of
+      Right ghc' -> pure ghc'
+      Left  bver -> do
+        spaths <- liftIO getSearchPath
+        throwMaybeM (NotFoundInPATH bver) $ liftIO (searchPath spaths bver)
+    pure (("GHC", bghcPath) : cEnv)
+
+
+
+
+    -------------
+    --[ Other ]--
+    -------------
+
+
+
+-- | Creates @ghc-x.y.z@ and @ghc-x.y@ symlinks. This is used for
+-- both installing from source and bindist.
+postGHCInstall :: ( MonadReader env m
+                  , HasDirs env
+                  , HasLog env
+                  , MonadThrow m
+                  , MonadFail m
+                  , MonadIO m
+                  , MonadCatch m
+                  , MonadMask m
+                  , MonadUnliftIO m
+                  )
+               => GHCTargetVersion
+               -> Excepts '[NotInstalled] m ()
+postGHCInstall ver@GHCTargetVersion {..} = do
+  void $ liftE $ setGHC ver SetGHC_XYZ Nothing
+
+  -- Create ghc-x.y symlinks. This may not be the current
+  -- version, create it regardless.
+  v' <-
+    handle (\(e :: ParseError) -> lift $ logWarn (T.pack $ displayException e) >> pure Nothing)
+    $ fmap Just
+    $ getMajorMinorV _tvVersion
+  forM_ v' $ \(mj, mi) -> lift (getGHCForPVP (PVP (fromIntegral mj :| [fromIntegral mi])) _tvTarget)
+    >>= mapM_ (\v -> liftE $ setGHC v SetGHC_XY Nothing)
+
diff --git a/lib/GHCup/HLS.hs b/lib/GHCup/HLS.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/HLS.hs
@@ -0,0 +1,723 @@
+{-# LANGUAGE CPP                   #-}
+{-# LANGUAGE BangPatterns          #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings     #-}
+{-# LANGUAGE QuasiQuotes           #-}
+
+{-|
+Module      : GHCup.HLS
+Description : GHCup installation functions for HLS
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+-}
+module GHCup.HLS where
+
+import           GHCup.Download
+import           GHCup.Errors
+import           GHCup.Types
+import           GHCup.Types.JSON               ( )
+import           GHCup.Types.Optics
+import           GHCup.Utils
+import           GHCup.Prelude
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.Process
+import           GHCup.Prelude.String.QQ
+
+import           Codec.Archive                  ( ArchiveResult )
+import           Control.Applicative
+import           Control.Exception.Safe
+import           Control.Monad
+#if !MIN_VERSION_base(4,13,0)
+import           Control.Monad.Fail             ( MonadFail )
+#endif
+import           Control.Monad.Reader
+import           Control.Monad.Trans.Resource
+                                         hiding ( throwM )
+import           Data.ByteString                ( ByteString )
+import           Data.Either
+import           Data.List
+import           Data.Maybe
+import           Data.String                    ( fromString )
+import           Data.Text                      ( Text )
+import           Data.Versions                hiding ( patch )
+import           Distribution.Types.Version   hiding ( Version )
+import           Distribution.Types.PackageId
+import           Distribution.Types.PackageDescription
+import           Distribution.Types.GenericPackageDescription
+import           Distribution.PackageDescription.Parsec
+import           GHC.IO.Exception
+import           Haskus.Utils.Variant.Excepts
+import           Optics
+import           Prelude                 hiding ( abs
+                                                , writeFile
+                                                )
+import           Safe                    hiding ( at )
+import           System.FilePath
+import           System.IO.Error
+import           Text.Regex.Posix
+import           URI.ByteString
+
+import qualified Data.List.NonEmpty            as NE
+import qualified Data.ByteString               as B
+import qualified Data.Text                     as T
+import qualified Text.Megaparsec               as MP
+import Text.PrettyPrint.HughesPJClass (prettyShow)
+
+
+data HLSVer = SourceDist Version
+            | GitDist GitBranch
+            | HackageDist Version
+            | RemoteDist URI
+
+
+
+    --------------------
+    --[ Installation ]--
+    --------------------
+
+
+-- | Like 'installHLSBin, except takes the 'DownloadInfo' as
+-- argument instead of looking it up from 'GHCupDownloads'.
+installHLSBindist :: ( MonadMask m
+                     , MonadCatch m
+                     , MonadReader env m
+                     , HasPlatformReq env
+                     , HasDirs env
+                     , HasSettings env
+                     , HasLog env
+                     , MonadResource m
+                     , MonadIO m
+                     , MonadUnliftIO m
+                     , MonadFail m
+                     )
+                  => DownloadInfo
+                  -> Version
+                  -> InstallDir -- ^ isolated install path, if user passed any
+                  -> Bool       -- ^ Force install
+                  -> Excepts
+                       '[ AlreadyInstalled
+                        , CopyError
+                        , DigestError
+                        , GPGError
+                        , DownloadFailed
+                        , NoDownload
+                        , NotInstalled
+                        , UnknownArchive
+                        , TarDirDoesNotExist
+                        , ArchiveResult
+                        , FileAlreadyExistsError
+                        , ProcessError
+                        , DirNotEmpty
+                        , UninstallFailed
+                        , MergeFileTreeError
+                        ]
+                       m
+                       ()
+installHLSBindist dlinfo ver installDir forceInstall = do
+  lift $ logDebug $ "Requested to install hls version " <> prettyVer ver
+
+  PlatformRequest {..} <- lift getPlatformReq
+  Dirs {..} <- lift getDirs
+
+  regularHLSInstalled <- lift $ hlsInstalled ver
+
+  if
+    | not forceInstall
+    , regularHLSInstalled
+    , GHCupInternal <- installDir -> do        -- regular install
+        throwE $ AlreadyInstalled HLS ver
+
+    | forceInstall
+    , regularHLSInstalled
+    , GHCupInternal <- installDir -> do        -- regular forced install
+        lift $ logInfo "Removing the currently installed version of HLS before force installing!"
+        liftE $ rmHLSVer ver
+
+    | otherwise -> pure ()
+
+  -- download (or use cached version)
+  dl <- liftE $ downloadCached dlinfo Nothing
+
+  -- unpack
+  tmpUnpack <- lift withGHCupTmpDir
+  liftE $ cleanUpOnError tmpUnpack (unpackToDir (fromGHCupPath tmpUnpack) dl)
+  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpUnpack)
+
+  -- the subdir of the archive where we do the work
+  workdir <- fromGHCupPath <$> maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
+  legacy <- liftIO $ isLegacyHLSBindist workdir
+
+  if
+    | not forceInstall
+    , not legacy
+    , (IsolateDir fp) <- installDir -> liftE $ installDestSanityCheck (IsolateDirResolved fp)
+    | otherwise -> pure ()
+
+  case installDir of
+    IsolateDir isoDir -> do
+      lift $ logInfo $ "isolated installing HLS to " <> T.pack isoDir
+      if legacy
+      then liftE $ installHLSUnpackedLegacy workdir (IsolateDirResolved isoDir) ver forceInstall
+      else liftE $ runBuildAction tmpUnpack $ installHLSUnpacked workdir (IsolateDirResolved isoDir) ver forceInstall
+
+    GHCupInternal -> do
+      if legacy
+      then liftE $ installHLSUnpackedLegacy workdir (GHCupBinDir binDir) ver forceInstall
+      else do
+        inst <- ghcupHLSDir ver
+        liftE $ runBuildAction tmpUnpack
+              $ installHLSUnpacked workdir (GHCupDir inst) ver forceInstall
+        liftE $ setHLS ver SetHLS_XYZ Nothing
+
+
+isLegacyHLSBindist :: FilePath -- ^ Path to the unpacked hls bindist
+                   -> IO Bool
+isLegacyHLSBindist path = do
+  not <$> doesFileExist (path </> "GNUmakefile")
+
+-- | Install an unpacked hls distribution.
+installHLSUnpacked :: ( MonadMask m
+                      , MonadUnliftIO m
+                      , MonadReader env m
+                      , MonadFail m
+                      , HasLog env
+                      , HasDirs env
+                      , HasSettings env
+                      , MonadCatch m
+                      , MonadIO m
+                      , MonadResource m
+                      , HasPlatformReq env
+                      )
+                   => FilePath      -- ^ Path to the unpacked hls bindist (where the executable resides)
+                   -> InstallDirResolved      -- ^ Path to install to
+                   -> Version
+                   -> Bool
+                   -> Excepts '[ProcessError, CopyError, FileAlreadyExistsError, NotInstalled, MergeFileTreeError] m ()
+installHLSUnpacked path inst ver forceInstall = do
+  PlatformRequest { .. } <- lift getPlatformReq
+  lift $ logInfo "Installing HLS"
+  tmpInstallDest <- lift withGHCupTmpDir
+  lEM $ make ["DESTDIR=" <> fromGHCupPath tmpInstallDest, "PREFIX=" <> fromInstallDir inst, "install"] (Just path)
+  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpInstallDest)
+  liftE $ mergeFileTree (tmpInstallDest `appendGHCupPath` dropDrive (fromInstallDir inst))
+                   inst
+                   HLS
+                   (mkTVer ver)
+                   (\f t -> liftIO $ do
+                       mtime <- ifM (pathIsSymbolicLink f) (pure Nothing) (Just <$> getModificationTime f)
+                       install f t (not forceInstall)
+                       forM_ mtime $ setModificationTime t)
+
+-- | Install an unpacked hls distribution (legacy).
+installHLSUnpackedLegacy :: (MonadReader env m, MonadFail m, HasLog env, MonadCatch m, MonadIO m)
+                         => FilePath      -- ^ Path to the unpacked hls bindist (where the executable resides)
+                         -> InstallDirResolved      -- ^ Path to install to
+                         -> Version
+                         -> Bool          -- ^ is it a force install
+                         -> Excepts '[CopyError, FileAlreadyExistsError] m ()
+installHLSUnpackedLegacy path installDir ver forceInstall = do
+  lift $ logInfo "Installing HLS"
+  liftIO $ createDirRecursive' (fromInstallDir installDir)
+
+  -- install haskell-language-server-<ghcver>
+  bins@(_:_) <- liftIO $ findFiles
+    path
+    (makeRegexOpts compExtended
+                   execBlank
+                   ([s|^haskell-language-server-[0-9].*$|] :: ByteString)
+    )
+  forM_ bins $ \f -> do
+    let toF = dropSuffix exeExt f
+              <> (case installDir of
+                   IsolateDirResolved _ -> ""
+                   _ -> ("~" <>) . T.unpack . prettyVer $ ver
+                 )
+              <> exeExt
+
+    let srcPath = path </> f
+    let destPath = fromInstallDir installDir </> toF
+
+    -- destination could be an existing symlink
+    -- for new make-based HLSes
+    liftIO $ rmFileForce destPath
+
+    copyFileE
+      srcPath
+      destPath
+      (not forceInstall)
+    lift $ chmod_755 destPath
+
+  -- install haskell-language-server-wrapper
+  let wrapper = "haskell-language-server-wrapper"
+      toF = wrapper
+            <> (case installDir of
+                 IsolateDirResolved _ -> ""
+                 _ -> ("-" <>) . T.unpack . prettyVer $ ver
+               )
+            <> exeExt
+      srcWrapperPath = path </> wrapper <> exeExt
+      destWrapperPath = fromInstallDir installDir </> toF
+
+  liftIO $ rmFileForce destWrapperPath
+  copyFileE
+    srcWrapperPath
+    destWrapperPath
+    (not forceInstall)
+
+  lift $ chmod_755 destWrapperPath
+
+
+
+-- | Installs hls binaries @haskell-language-server-\<ghcver\>@
+-- into @~\/.ghcup\/bin/@, as well as @haskell-languager-server-wrapper@.
+installHLSBin :: ( MonadMask m
+                 , MonadCatch m
+                 , MonadReader env m
+                 , HasPlatformReq env
+                 , HasGHCupInfo env
+                 , HasDirs env
+                 , HasSettings env
+                 , HasLog env
+                 , MonadResource m
+                 , MonadIO m
+                 , MonadUnliftIO m
+                 , MonadFail m
+                 )
+              => Version
+              -> InstallDir
+              -> Bool            -- force install
+              -> Excepts
+                   '[ AlreadyInstalled
+                    , CopyError
+                    , DigestError
+                    , GPGError
+                    , DownloadFailed
+                    , NoDownload
+                    , NotInstalled
+                    , UnknownArchive
+                    , TarDirDoesNotExist
+                    , ArchiveResult
+                    , FileAlreadyExistsError
+                    , ProcessError
+                    , DirNotEmpty
+                    , UninstallFailed
+                    , MergeFileTreeError
+                    ]
+                   m
+                   ()
+installHLSBin ver installDir forceInstall = do
+  dlinfo <- liftE $ getDownloadInfo HLS ver
+  installHLSBindist dlinfo ver installDir forceInstall
+
+
+compileHLS :: ( MonadMask m
+              , MonadCatch m
+              , MonadReader env m
+              , HasDirs env
+              , HasSettings env
+              , HasPlatformReq env
+              , HasGHCupInfo env
+              , HasLog env
+              , MonadResource m
+              , MonadIO m
+              , MonadUnliftIO m
+              , MonadFail m
+              )
+           => HLSVer
+           -> [Version]
+           -> Maybe Int
+           -> Either Bool Version
+           -> InstallDir
+           -> Maybe (Either FilePath URI)
+           -> Maybe URI
+           -> Bool
+           -> Maybe (Either FilePath [URI])  -- ^ patches
+           -> [Text]                   -- ^ additional args to cabal install
+           -> Excepts '[ NoDownload
+                       , GPGError
+                       , DownloadFailed
+                       , DigestError
+                       , UnknownArchive
+                       , TarDirDoesNotExist
+                       , ArchiveResult
+                       , BuildFailed
+                       , NotInstalled
+                       ] m Version
+compileHLS targetHLS ghcs jobs ov installDir cabalProject cabalProjectLocal updateCabal patches cabalArgs = do
+  PlatformRequest { .. } <- lift getPlatformReq
+  GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
+  Dirs { .. } <- lift getDirs
+
+  when updateCabal $ reThrowAll @_ @'[ProcessError] DownloadFailed $ do
+    lift $ logInfo "Updating cabal DB"
+    lEM $ exec "cabal" ["update"] (Just $ fromGHCupPath tmpDir) Nothing
+
+  (workdir, tmpUnpack, tver, git_describe) <- case targetHLS of
+    -- unpack from version tarball
+    SourceDist tver -> do
+      lift $ logDebug $ "Requested to compile: " <> prettyVer tver
+
+      -- download source tarball
+      dlInfo <-
+        preview (ix HLS % ix tver % viSourceDL % _Just) dls
+          ?? NoDownload
+      dl <- liftE $ downloadCached dlInfo Nothing
+
+      -- unpack
+      tmpUnpack <- lift mkGhcupTmpDir
+      liftE $ cleanUpOnError tmpUnpack (unpackToDir (fromGHCupPath tmpUnpack) dl)
+      liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpUnpack)
+
+      workdir <- maybe (pure tmpUnpack)
+                       (liftE . intoSubdir tmpUnpack)
+                       (view dlSubdir dlInfo)
+
+      pure (workdir, tmpUnpack, tver, Nothing)
+
+    HackageDist tver -> do
+      lift $ logDebug $ "Requested to compile (from hackage): " <> prettyVer tver
+
+      -- download source tarball
+      tmpUnpack <- lift mkGhcupTmpDir
+      let hls = "haskell-language-server-" <> T.unpack (prettyVer tver)
+      reThrowAll @_ @'[ProcessError] DownloadFailed $ do
+        -- unpack
+        lEM $ exec "cabal" ["unpack", hls] (Just $ fromGHCupPath tmpUnpack) Nothing
+
+      let workdir = appendGHCupPath tmpUnpack hls
+
+      pure (workdir, tmpUnpack, tver, Nothing)
+
+    RemoteDist uri -> do
+      lift $ logDebug $ "Requested to compile (from uri): " <> T.pack (show uri)
+
+      -- download source tarball
+      tmpDownload <- lift withGHCupTmpDir
+      tmpUnpack <- lift mkGhcupTmpDir
+      tar <- liftE $ download uri Nothing Nothing (fromGHCupPath tmpDownload) Nothing False
+      (cf, tver) <- liftE $ cleanUpOnError tmpUnpack $ do
+        unpackToDir (fromGHCupPath tmpUnpack) tar
+        let regex = [s|^(.*/)*haskell-language-server\.cabal$|] :: B.ByteString
+        [cabalFile] <- liftIO $ findFilesDeep
+          tmpUnpack
+          (makeRegexOpts compExtended
+                         execBlank
+                         regex
+          )
+        tver <- getCabalVersion (fromGHCupPath tmpUnpack </> cabalFile)
+        pure (cabalFile, tver)
+
+      let workdir = appendGHCupPath tmpUnpack (takeDirectory cf)
+
+      pure (workdir, tmpUnpack, tver, Nothing)
+
+    -- clone from git
+    GitDist GitBranch{..} -> do
+      tmpUnpack <- lift mkGhcupTmpDir
+      let git args = execLogged "git" ("--no-pager":args) (Just $ fromGHCupPath tmpUnpack) "git" Nothing
+      reThrowAll @_ @'[ProcessError] DownloadFailed $ do
+        let rep = fromMaybe "https://github.com/haskell/haskell-language-server.git" repo
+        lift $ logInfo $ "Fetching git repo " <> T.pack rep <> " at ref " <> T.pack ref <> " (this may take a while)"
+        lEM $ git [ "init" ]
+        lEM $ git [ "remote"
+                  , "add"
+                  , "origin"
+                  , fromString rep ]
+
+        -- figure out if we can do a shallow clone
+        remoteBranches <- catchE @ProcessError @'[ProcessError] @'[] (\_ -> pure [])
+            $ fmap processBranches $ gitOut ["ls-remote", "--heads", "origin"] (fromGHCupPath tmpUnpack)
+        let shallow_clone
+              | gitDescribeRequested                 = False
+              | isCommitHash ref                     = True
+              | fromString ref `elem` remoteBranches = True
+              | otherwise                            = False
+
+        lift $ logDebug $ "Shallow clone: " <> T.pack (show shallow_clone)
+
+        -- fetch
+        let fetch_args
+              | shallow_clone = ["fetch", "--depth", "1", "--quiet", "origin", fromString ref]
+              | otherwise     = ["fetch", "--tags",       "--quiet", "origin"                ]
+        lEM $ git fetch_args
+
+        -- checkout
+        lEM $ git [ "checkout", fromString ref ]
+
+        -- gather some info
+        git_describe <- if shallow_clone
+                        then pure Nothing
+                        else fmap Just $ gitOut ["describe", "--tags"] (fromGHCupPath tmpUnpack)
+        chash <- gitOut ["rev-parse", "HEAD" ] (fromGHCupPath tmpUnpack)
+        tver <- getCabalVersion (fromGHCupPath tmpUnpack </> "haskell-language-server.cabal")
+
+        liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpUnpack)
+        lift $ logInfo $ "Examining git ref " <> T.pack ref <> "\n  " <>
+                                    "HLS version (from cabal file): " <> prettyVer tver <>
+                                    (if not shallow_clone then "\n  " <> "'git describe' output: " <> fromJust git_describe else mempty) <>
+                                    (if isCommitHash ref then mempty else "\n  " <> "commit hash: " <> chash)
+
+        pure (tmpUnpack, tmpUnpack, tver, git_describe)
+
+  -- the version that's installed may differ from the
+  -- compiled version, so the user can overwrite it
+  installVer <- case ov of
+                  Left True -> case git_describe of
+                                 -- git describe
+                                 Just h -> either (fail . displayException) pure . version $ h
+                                 -- git describe, but not building from git, lol
+                                 Nothing -> pure tver
+                  -- default: use detected version
+                  Left False -> pure tver
+                  -- overwrite version with users value
+                  Right v -> pure v
+
+  liftE $ runBuildAction
+    tmpUnpack
+    (reThrowAll @_ @'[GPGError, DownloadFailed, DigestError, PatchFailed, ProcessError, FileAlreadyExistsError, CopyError] @'[BuildFailed] (BuildFailed $ fromGHCupPath workdir) $ do
+      let tmpInstallDir = fromGHCupPath workdir </> "out"
+      liftIO $ createDirRecursive' tmpInstallDir
+
+      -- apply patches
+      liftE $ applyAnyPatch patches (fromGHCupPath workdir)
+
+      -- set up project files
+      cp <- case cabalProject of
+        Just (Left cp)
+          | isAbsolute cp -> do
+              copyFileE cp (fromGHCupPath workdir </> "cabal.project") False
+              pure "cabal.project"
+          | otherwise -> pure (takeFileName cp)
+        Just (Right uri) -> do
+          tmpUnpack' <- lift withGHCupTmpDir
+          cp <- liftE $ download uri Nothing Nothing (fromGHCupPath tmpUnpack') (Just "cabal.project") False
+          copyFileE cp (fromGHCupPath workdir </> "cabal.project") False
+          pure "cabal.project"
+        Nothing
+          | HackageDist _ <- targetHLS -> do
+              liftIO $ B.writeFile (fromGHCupPath workdir </> "cabal.project") "packages: ./"
+              pure "cabal.project"
+          | RemoteDist _ <- targetHLS -> do
+              let cabalFile = fromGHCupPath workdir </> "cabal.project"
+              liftIO $ whenM (not <$> doesFileExist cabalFile) $ B.writeFile cabalFile "packages: ./"
+              pure "cabal.project"
+          | otherwise -> pure "cabal.project"
+      forM_ cabalProjectLocal $ \uri -> do
+        tmpUnpack' <- lift withGHCupTmpDir
+        cpl <- liftE $ download uri Nothing Nothing (fromGHCupPath tmpUnpack') (Just (cp <.> "local")) False
+        copyFileE cpl (fromGHCupPath workdir </> cp <.> "local") False
+      artifacts <- forM (sort ghcs) $ \ghc -> do
+        let ghcInstallDir = tmpInstallDir </> T.unpack (prettyVer ghc)
+        liftIO $ createDirRecursive' tmpInstallDir
+        lift $ logInfo $ "Building HLS " <> prettyVer installVer <> " for GHC version " <> prettyVer ghc
+        liftE $ lEM @_ @'[ProcessError] $
+          execLogged "cabal" ( [ "v2-install"
+                               , "-w"
+                               , "ghc-" <> T.unpack (prettyVer ghc)
+                               , "--install-method=copy"
+                               ] ++
+                               maybe [] (\j -> ["--jobs=" <> show j]) jobs ++
+                               [ "--overwrite-policy=always"
+                               , "--disable-profiling"
+                               , "--disable-tests"
+                               , "--installdir=" <> ghcInstallDir
+                               , "--project-file=" <> cp
+                               ] ++ fmap T.unpack cabalArgs ++ [
+                                 "exe:haskell-language-server"
+                               , "exe:haskell-language-server-wrapper"]
+                             )
+                             (Just $ fromGHCupPath workdir)
+                             "cabal"
+                             Nothing
+        pure ghcInstallDir
+
+      forM_ artifacts $ \artifact -> do
+        logDebug $ T.pack (show artifact)
+        liftIO $ renameFile (artifact </> "haskell-language-server" <.> exeExt)
+          (tmpInstallDir </> "haskell-language-server-" <> takeFileName artifact <.> exeExt)
+        liftIO $ renameFile (artifact </> "haskell-language-server-wrapper" <.> exeExt)
+          (tmpInstallDir </> "haskell-language-server-wrapper" <.> exeExt)
+
+      case installDir of
+        IsolateDir isoDir -> do
+          lift $ logInfo $ "isolated installing HLS to " <> T.pack isoDir
+          liftE $ installHLSUnpackedLegacy tmpInstallDir (IsolateDirResolved isoDir) installVer True
+        GHCupInternal -> do
+          liftE $ installHLSUnpackedLegacy tmpInstallDir (GHCupBinDir binDir) installVer True
+    )
+
+  pure installVer
+ where
+  gitDescribeRequested = case ov of
+                           Left b -> b
+                           _      -> False
+
+
+    -----------------
+    --[ Set/Unset ]--
+    -----------------
+
+-- | Set the haskell-language-server symlinks.
+setHLS :: ( MonadReader env m
+          , HasDirs env
+          , HasLog env
+          , MonadIO m
+          , MonadMask m
+          , MonadFail m
+          , MonadUnliftIO m
+          )
+       => Version
+       -> SetHLS
+       -> Maybe FilePath  -- if set, signals that we're not operating in ~/.ghcup/bin
+                          -- and don't want mess with other versions
+       -> Excepts '[NotInstalled] m ()
+setHLS ver shls mBinDir = do
+  whenM (lift $ not <$> hlsInstalled ver) (throwE (NotInstalled HLS (GHCTargetVersion Nothing ver)))
+
+  -- symlink destination
+  binDir <- case mBinDir of
+    Just x -> pure x
+    Nothing -> do
+      Dirs {binDir = f} <- lift getDirs
+      pure f
+
+  -- first delete the old symlinks
+  when (isNothing mBinDir) $
+    case shls of
+      -- not for legacy
+      SetHLS_XYZ -> liftE $ rmMinorHLSSymlinks ver
+      -- legacy and new
+      SetHLSOnly -> liftE rmPlainHLS
+
+  case shls of
+    -- not for legacy
+    SetHLS_XYZ -> do
+      bins <- lift $ hlsInternalServerScripts ver Nothing
+
+      forM_ bins $ \f -> do
+        let fname = takeFileName f
+        destL <- binarySymLinkDestination binDir f
+        let target = if "haskell-language-server-wrapper" `isPrefixOf` fname
+                     then fname <> "-" <> T.unpack (prettyVer ver) <> exeExt
+                     else fname <> "~" <> T.unpack (prettyVer ver) <> exeExt
+        lift $ createLink destL (binDir </> target)
+
+    -- legacy and new
+    SetHLSOnly -> do
+      -- set haskell-language-server-<ghcver> symlinks
+      bins <- lift $ hlsServerBinaries ver Nothing
+      when (null bins) $ throwE $ NotInstalled HLS (GHCTargetVersion Nothing ver)
+
+      forM_ bins $ \f -> do
+        let destL = f
+        let target = (<> exeExt) . head . splitOn "~" $ f
+        lift $ createLink destL (binDir </> target)
+
+      -- set haskell-language-server-wrapper symlink
+      let destL = "haskell-language-server-wrapper-" <> T.unpack (prettyVer ver) <> exeExt
+      let wrapper = binDir </> "haskell-language-server-wrapper" <> exeExt
+
+      lift $ createLink destL wrapper
+
+      when (isNothing mBinDir) $
+        lift warnAboutHlsCompatibility
+
+      liftIO (isShadowed wrapper) >>= \case
+        Nothing -> pure ()
+        Just pa -> lift $ logWarn $ T.pack $ prettyShow (ToolShadowed HLS pa wrapper ver)
+
+
+unsetHLS :: ( MonadMask m
+            , MonadReader env m
+            , HasDirs env
+            , MonadIO m)
+         => m ()
+unsetHLS = do
+  Dirs {..} <- getDirs
+  let wrapper = binDir </> "haskell-language-server-wrapper" <> exeExt
+  bins   <- liftIO $ handleIO (\_ -> pure []) $ findFiles'
+    binDir
+    (MP.chunk "haskell-language-server-" <* pvp' <* MP.chunk (T.pack exeExt) <* MP.eof)
+  forM_ bins (hideError doesNotExistErrorType . rmLink . (binDir </>))
+  hideError doesNotExistErrorType $ rmLink wrapper
+
+
+
+
+    ---------------
+    --[ Removal ]--
+    ---------------
+
+
+-- | Delete a hls version. Will try to fix the hls symlinks
+-- after removal (e.g. setting it to an older version).
+rmHLSVer :: ( MonadMask m
+            , MonadReader env m
+            , HasDirs env
+            , MonadThrow m
+            , HasLog env
+            , MonadIO m
+            , MonadFail m
+            , MonadCatch m
+            , MonadUnliftIO m
+            )
+         => Version
+         -> Excepts '[NotInstalled, UninstallFailed] m ()
+rmHLSVer ver = do
+  whenM (lift $ fmap not $ hlsInstalled ver) $ throwE (NotInstalled HLS (GHCTargetVersion Nothing ver))
+
+  isHlsSet <- lift hlsSet
+
+  liftE $ rmMinorHLSSymlinks ver
+
+  when (Just ver == isHlsSet) $ do
+    -- delete all set symlinks
+    liftE rmPlainHLS
+
+  hlsDir' <- ghcupHLSDir ver
+  let hlsDir = fromGHCupPath hlsDir'
+  lift (getInstalledFiles HLS (mkTVer ver)) >>= \case
+    Just files -> do
+      lift $ logInfo $ "Removing files safely from: " <> T.pack hlsDir
+      forM_ files (lift . hideError NoSuchThing . recycleFile . (\f -> hlsDir </> dropDrive f))
+      removeEmptyDirsRecursive hlsDir
+      survivors <- liftIO $ hideErrorDef [doesNotExistErrorType] [] $ listDirectory hlsDir
+      f <- recordedInstallationFile HLS (mkTVer ver)
+      lift $ recycleFile f
+      when (not (null survivors)) $ throwE $ UninstallFailed hlsDir survivors
+    Nothing -> do
+      isDir <- liftIO $ doesDirectoryExist hlsDir
+      isSyml <- liftIO $ handleIO (\_ -> pure False) $ pathIsSymbolicLink hlsDir
+      when (isDir && not isSyml) $ do
+        lift $ logInfo $ "Removing legacy directory recursively: " <> T.pack hlsDir
+        recyclePathForcibly hlsDir'
+
+  when (Just ver == isHlsSet) $ do
+    -- set latest hls
+    hlsVers <- lift $ fmap rights getInstalledHLSs
+    case headMay . reverse . sort $ hlsVers of
+      Just latestver -> liftE $ setHLS latestver SetHLSOnly Nothing
+      Nothing        -> pure ()
+
+
+getCabalVersion :: (MonadIO m, MonadFail m) => FilePath -> m Version
+getCabalVersion fp = do
+  contents <- liftIO $ B.readFile fp
+  gpd <- case parseGenericPackageDescriptionMaybe contents of
+           Nothing -> fail $ "could not parse cabal file: " <> fp
+           Just r -> pure r
+  let tver = (\c -> Version Nothing c [] Nothing)
+           . NE.fromList . fmap (NE.fromList . (:[]) . digits . fromIntegral)
+           . versionNumbers
+           . pkgVersion
+           . package
+           . packageDescription
+           $ gpd
+  pure tver
diff --git a/lib/GHCup/List.hs b/lib/GHCup/List.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/List.hs
@@ -0,0 +1,410 @@
+{-# LANGUAGE CPP                   #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings     #-}
+
+{-|
+Module      : GHCup.List
+Description : Listing versions and tools
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+-}
+module GHCup.List where
+
+import           GHCup.Download
+import           GHCup.Errors
+import           GHCup.Types
+import           GHCup.Types.JSON               ( )
+import           GHCup.Types.Optics
+import           GHCup.Utils
+import           GHCup.Prelude.Logger
+import           GHCup.Version
+
+import           Control.Applicative
+import           Control.Exception.Safe
+import           Control.Monad
+#if !MIN_VERSION_base(4,13,0)
+import           Control.Monad.Fail             ( MonadFail )
+#endif
+import           Control.Monad.Reader
+import           Data.Either
+import           Data.List
+import           Data.Maybe
+import           Data.Text                      ( Text )
+import           Data.Versions                hiding ( patch )
+import           Haskus.Utils.Variant.Excepts
+import           Optics
+import           Prelude                 hiding ( abs
+                                                , writeFile
+                                                )
+
+import qualified Data.Map.Strict               as Map
+import qualified Data.Text                     as T
+
+
+
+
+
+
+
+
+
+
+    ------------------
+    --[ List tools ]--
+    ------------------
+
+
+-- | Filter data type for 'listVersions'.
+data ListCriteria = ListInstalled
+                  | ListSet
+                  | ListAvailable
+                  deriving Show
+
+-- | A list result describes a single tool version
+-- and various of its properties.
+data ListResult = ListResult
+  { lTool      :: Tool
+  , lVer       :: Version
+  , lCross     :: Maybe Text -- ^ currently only for GHC
+  , lTag       :: [Tag]
+  , lInstalled :: Bool
+  , lSet       :: Bool -- ^ currently active version
+  , fromSrc    :: Bool -- ^ compiled from source
+  , lStray     :: Bool -- ^ not in download info
+  , lNoBindist :: Bool -- ^ whether the version is available for this platform/arch
+  , hlsPowered :: Bool
+  }
+  deriving (Eq, Ord, Show)
+
+
+-- | Extract all available tool versions and their tags.
+availableToolVersions :: GHCupDownloads -> Tool -> Map.Map Version VersionInfo
+availableToolVersions av tool = view
+  (at tool % non Map.empty)
+  av
+
+
+-- | List all versions from the download info, as well as stray
+-- versions.
+listVersions :: ( MonadCatch m
+                , HasLog env
+                , MonadThrow m
+                , HasLog env
+                , MonadIO m
+                , MonadReader env m
+                , HasDirs env
+                , HasPlatformReq env
+                , HasGHCupInfo env
+                )
+             => Maybe Tool
+             -> Maybe ListCriteria
+             -> m [ListResult]
+listVersions lt' criteria = do
+  -- some annoying work to avoid too much repeated IO
+  cSet <- cabalSet
+  cabals <- getInstalledCabals
+  hlsSet' <- hlsSet
+  hlses <- getInstalledHLSs
+  sSet <- stackSet
+  stacks <- getInstalledStacks
+
+  go lt' cSet cabals hlsSet' hlses sSet stacks
+ where
+  go lt cSet cabals hlsSet' hlses sSet stacks = do
+    case lt of
+      Just t -> do
+        GHCupInfo { _ghcupDownloads = dls } <- getGHCupInfo
+        -- get versions from GHCupDownloads
+        let avTools = availableToolVersions dls t
+        lr <- filter' <$> forM (Map.toList avTools) (toListResult t cSet cabals hlsSet' hlses sSet stacks)
+
+        case t of
+          GHC -> do
+            slr <- strayGHCs avTools
+            pure (sort (slr ++ lr))
+          Cabal -> do
+            slr <- strayCabals avTools cSet cabals
+            pure (sort (slr ++ lr))
+          HLS -> do
+            slr <- strayHLS avTools hlsSet' hlses
+            pure (sort (slr ++ lr))
+          Stack -> do
+            slr <- strayStacks avTools sSet stacks
+            pure (sort (slr ++ lr))
+          GHCup -> do
+            let cg = maybeToList $ currentGHCup avTools
+            pure (sort (cg ++ lr))
+      Nothing -> do
+        ghcvers   <- go (Just GHC) cSet cabals hlsSet' hlses sSet stacks
+        cabalvers <- go (Just Cabal) cSet cabals hlsSet' hlses sSet stacks
+        hlsvers   <- go (Just HLS) cSet cabals hlsSet' hlses sSet stacks
+        ghcupvers <- go (Just GHCup) cSet cabals hlsSet' hlses sSet stacks
+        stackvers <- go (Just Stack) cSet cabals hlsSet' hlses sSet stacks
+        pure (ghcvers <> cabalvers <> hlsvers <> stackvers <> ghcupvers)
+  strayGHCs :: ( MonadCatch m
+               , MonadReader env m
+               , HasDirs env
+               , MonadThrow m
+               , HasLog env
+               , MonadIO m
+               )
+            => Map.Map Version VersionInfo
+            -> m [ListResult]
+  strayGHCs avTools = do
+    ghcs <- getInstalledGHCs
+    fmap catMaybes $ forM ghcs $ \case
+      Right tver@GHCTargetVersion{ _tvTarget = Nothing, .. } -> do
+        case Map.lookup _tvVersion avTools of
+          Just _  -> pure Nothing
+          Nothing -> do
+            lSet    <- fmap (maybe False (\(GHCTargetVersion _ v ) -> v == _tvVersion)) $ ghcSet Nothing
+            fromSrc <- ghcSrcInstalled tver
+            hlsPowered <- fmap (elem _tvVersion) hlsGHCVersions
+            pure $ Just $ ListResult
+              { lTool      = GHC
+              , lVer       = _tvVersion
+              , lCross     = Nothing
+              , lTag       = []
+              , lInstalled = True
+             , lStray     = isNothing (Map.lookup _tvVersion avTools)
+              , lNoBindist = False
+              , ..
+              }
+      Right tver@GHCTargetVersion{ .. } -> do
+        lSet    <- fmap (maybe False (\(GHCTargetVersion _ v ) -> v == _tvVersion)) $ ghcSet _tvTarget
+        fromSrc <- ghcSrcInstalled tver
+        hlsPowered <- fmap (elem _tvVersion) hlsGHCVersions
+        pure $ Just $ ListResult
+          { lTool      = GHC
+          , lVer       = _tvVersion
+          , lCross     = _tvTarget
+          , lTag       = []
+          , lInstalled = True
+          , lStray     = True -- NOTE: cross currently cannot be installed via bindist
+          , lNoBindist = False
+          , ..
+          }
+      Left e -> do
+        logWarn
+          $ "Could not parse version of stray directory" <> T.pack e
+        pure Nothing
+
+  strayCabals :: ( MonadReader env m
+                 , HasDirs env
+                 , MonadCatch m
+                 , MonadThrow m
+                 , HasLog env
+                 , MonadIO m
+                 )
+            => Map.Map Version VersionInfo
+            -> Maybe Version
+            -> [Either FilePath Version]
+            -> m [ListResult]
+  strayCabals avTools cSet cabals = do
+    fmap catMaybes $ forM cabals $ \case
+      Right ver ->
+        case Map.lookup ver avTools of
+          Just _  -> pure Nothing
+          Nothing -> do
+            let lSet = cSet == Just ver
+            pure $ Just $ ListResult
+              { lTool      = Cabal
+              , lVer       = ver
+              , lCross     = Nothing
+              , lTag       = []
+              , lInstalled = True
+              , lStray     = isNothing (Map.lookup ver avTools)
+              , lNoBindist = False
+              , fromSrc    = False -- actually, we don't know :>
+              , hlsPowered = False
+              , ..
+              }
+      Left e -> do
+        logWarn
+          $ "Could not parse version of stray directory" <> T.pack e
+        pure Nothing
+
+  strayHLS :: ( MonadReader env m
+              , HasDirs env
+              , MonadCatch m
+              , MonadThrow m
+              , HasLog env
+              , MonadIO m)
+           => Map.Map Version VersionInfo
+           -> Maybe Version
+           -> [Either FilePath Version]
+           -> m [ListResult]
+  strayHLS avTools hlsSet' hlss = do
+    fmap catMaybes $ forM hlss $ \case
+      Right ver ->
+        case Map.lookup ver avTools of
+          Just _  -> pure Nothing
+          Nothing -> do
+            let lSet = hlsSet' == Just ver
+            pure $ Just $ ListResult
+              { lTool      = HLS
+              , lVer       = ver
+              , lCross     = Nothing
+              , lTag       = []
+              , lInstalled = True
+              , lStray     = isNothing (Map.lookup ver avTools)
+              , lNoBindist = False
+              , fromSrc    = False -- actually, we don't know :>
+              , hlsPowered = False
+              , ..
+              }
+      Left e -> do
+        logWarn
+          $ "Could not parse version of stray directory" <> T.pack e
+        pure Nothing
+
+  strayStacks :: ( MonadReader env m
+                 , HasDirs env
+                 , MonadCatch m
+                 , MonadThrow m
+                 , HasLog env
+                 , MonadIO m
+                 )
+              => Map.Map Version VersionInfo
+              -> Maybe Version
+              -> [Either FilePath Version]
+              -> m [ListResult]
+  strayStacks avTools stackSet' stacks = do
+    fmap catMaybes $ forM stacks $ \case
+      Right ver ->
+        case Map.lookup ver avTools of
+          Just _  -> pure Nothing
+          Nothing -> do
+            let lSet = stackSet' == Just ver
+            pure $ Just $ ListResult
+              { lTool      = Stack
+              , lVer       = ver
+              , lCross     = Nothing
+              , lTag       = []
+              , lInstalled = True
+              , lStray     = isNothing (Map.lookup ver avTools)
+              , lNoBindist = False
+              , fromSrc    = False -- actually, we don't know :>
+              , hlsPowered = False
+              , ..
+              }
+      Left e -> do
+        logWarn
+          $ "Could not parse version of stray directory" <> T.pack e
+        pure Nothing
+
+  currentGHCup :: Map.Map Version VersionInfo -> Maybe ListResult
+  currentGHCup av =
+    let currentVer = fromJust $ pvpToVersion ghcUpVer ""
+        listVer    = Map.lookup currentVer av
+        latestVer  = fst <$> headOf (getTagged Latest) av
+        recommendedVer = fst <$> headOf (getTagged Latest) av
+        isOld  = maybe True (> currentVer) latestVer && maybe True (> currentVer) recommendedVer
+    in if | Map.member currentVer av -> Nothing
+          | otherwise -> Just $ ListResult { lVer    = currentVer
+                                           , lTag    = maybe (if isOld then [Old] else []) _viTags listVer
+                                           , lCross  = Nothing
+                                           , lTool   = GHCup
+                                           , fromSrc = False
+                                           , lStray  = isNothing listVer
+                                           , lSet    = True
+                                           , lInstalled = True
+                                           , lNoBindist = False
+                                           , hlsPowered = False
+                                           }
+
+  -- NOTE: this are not cross ones, because no bindists
+  toListResult :: ( HasLog env
+                  , MonadReader env m
+                  , HasDirs env
+                  , HasGHCupInfo env
+                  , HasPlatformReq env
+                  , MonadIO m
+                  , MonadCatch m
+                  )
+               => Tool
+               -> Maybe Version
+               -> [Either FilePath Version]
+               -> Maybe Version
+               -> [Either FilePath Version]
+               -> Maybe Version
+               -> [Either FilePath Version]
+               -> (Version, VersionInfo)
+               -> m ListResult
+  toListResult t cSet cabals hlsSet' hlses stackSet' stacks (v, _viTags -> tags) = do
+    case t of
+      GHC -> do
+        lNoBindist <- fmap (isLeft . veitherToEither) $ runE @'[NoDownload] $ getDownloadInfo GHC v
+        let tver = mkTVer v
+        lSet       <- fmap (maybe False (\(GHCTargetVersion _ v') -> v' == v)) $ ghcSet Nothing
+        lInstalled <- ghcInstalled tver
+        fromSrc    <- ghcSrcInstalled tver
+        hlsPowered <- fmap (elem v) hlsGHCVersions
+        pure ListResult { lVer = v, lCross = Nothing , lTag = tags, lTool = t, lStray = False, .. }
+      Cabal -> do
+        lNoBindist <- fmap (isLeft . veitherToEither) $ runE @'[NoDownload] $ getDownloadInfo Cabal v
+        let lSet = cSet == Just v
+        let lInstalled = elem v $ rights cabals
+        pure ListResult { lVer    = v
+                        , lCross  = Nothing
+                        , lTag    = tags
+                        , lTool   = t
+                        , fromSrc = False
+                        , lStray  = False
+                        , hlsPowered = False
+                        , ..
+                        }
+      GHCup -> do
+        let lSet       = prettyPVP ghcUpVer == prettyVer v
+        let lInstalled = lSet
+        pure ListResult { lVer    = v
+                        , lTag    = tags
+                        , lCross  = Nothing
+                        , lTool   = t
+                        , fromSrc = False
+                        , lStray  = False
+                        , lNoBindist = False
+                        , hlsPowered = False
+                        , ..
+                        }
+      HLS -> do
+        lNoBindist <- fmap (isLeft . veitherToEither) $ runE @'[NoDownload] $ getDownloadInfo HLS v
+        let lSet = hlsSet' == Just v
+        let lInstalled = elem v $ rights hlses
+        pure ListResult { lVer    = v
+                        , lCross  = Nothing
+                        , lTag    = tags
+                        , lTool   = t
+                        , fromSrc = False
+                        , lStray  = False
+                        , hlsPowered = False
+                        , ..
+                        }
+      Stack -> do
+        lNoBindist <- fmap (isLeft . veitherToEither) $ runE @'[NoDownload] $ getDownloadInfo Stack v
+        let lSet = stackSet' == Just v
+        let lInstalled = elem v $ rights stacks
+        pure ListResult { lVer    = v
+                        , lCross  = Nothing
+                        , lTag    = tags
+                        , lTool   = t
+                        , fromSrc = False
+                        , lStray  = False
+                        , hlsPowered = False
+                        , ..
+                        }
+
+
+  filter' :: [ListResult] -> [ListResult]
+  filter' lr = case criteria of
+    Nothing            -> lr
+    Just ListInstalled -> filter (\ListResult {..} -> lInstalled) lr
+    Just ListSet       -> filter (\ListResult {..} -> lSet) lr
+    Just ListAvailable -> filter (\ListResult {..} -> not lNoBindist) lr
+
diff --git a/lib/GHCup/Platform.hs b/lib/GHCup/Platform.hs
--- a/lib/GHCup/Platform.hs
+++ b/lib/GHCup/Platform.hs
@@ -23,10 +23,11 @@
 import           GHCup.Types
 import           GHCup.Types.Optics
 import           GHCup.Types.JSON               ( )
-import           GHCup.Utils.File
-import           GHCup.Utils.Logger
-import           GHCup.Utils.Prelude
-import           GHCup.Utils.String.QQ
+import           GHCup.Utils.Dirs
+import           GHCup.Prelude
+import           GHCup.Prelude.Logger
+import           GHCup.Prelude.Process
+import           GHCup.Prelude.String.QQ
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -46,7 +47,6 @@
                                                 , writeFile
                                                 )
 import           System.Info
-import           System.Directory
 import           System.OsRelease
 import           Text.PrettyPrint.HughesPJClass ( prettyShow )
 import           Text.Regex.Posix
diff --git a/lib/GHCup/Prelude.hs b/lib/GHCup/Prelude.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude.hs
@@ -0,0 +1,82 @@
+{-# LANGUAGE CPP                 #-}
+{-# LANGUAGE DataKinds           #-}
+{-# LANGUAGE FlexibleContexts    #-}
+{-# LANGUAGE FlexibleInstances   #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeFamilies        #-}
+{-# LANGUAGE TypeOperators       #-}
+
+{-|
+Module      : GHCup.Prelude
+Description : MegaParsec utilities
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+
+GHCup specific prelude. Lots of Excepts functionality.
+-}
+module GHCup.Prelude
+  (module GHCup.Prelude,
+   module GHCup.Prelude.Internal,
+#if defined(IS_WINDOWS)
+   module GHCup.Prelude.Windows
+#else
+   module GHCup.Prelude.Posix
+#endif
+  )
+where
+
+import           GHCup.Errors
+import           GHCup.Prelude.Internal
+import           GHCup.Types.Optics   (HasLog)
+import           GHCup.Prelude.Logger (logWarn)
+#if defined(IS_WINDOWS)
+import GHCup.Prelude.Windows
+#else
+import GHCup.Prelude.Posix
+#endif
+
+import           Control.Monad.IO.Class
+import           Control.Monad.Reader
+import           Haskus.Utils.Variant.Excepts
+import           Text.PrettyPrint.HughesPJClass ( prettyShow, Pretty )
+import qualified Data.Text                     as T
+
+
+
+-- for some obscure reason... this won't type-check if we move it to a different module
+catchWarn :: forall es m env . ( Pretty (V es)
+                             , MonadReader env m
+                             , HasLog env
+                             , MonadIO m
+                             , Monad m) => Excepts es m () -> Excepts '[] m ()
+catchWarn = catchAllE @_ @es (\v -> lift $ logWarn (T.pack . prettyShow $ v))
+
+
+runBothE' :: forall e m a b .
+             ( Monad m
+             , Show (V e)
+             , Pretty (V e)
+             , PopVariant InstallSetError e
+             , LiftVariant' e (InstallSetError ': e)
+             , e :<< (InstallSetError ': e)
+             )
+          => Excepts e m a
+          -> Excepts e m b
+          -> Excepts (InstallSetError ': e) m ()
+runBothE' a1 a2 = do
+   r1 <- lift $ runE @e a1
+   r2 <- lift $ runE @e a2
+   case (r1, r2) of
+      (VLeft e1, VLeft e2) -> throwE (InstallSetError e1 e2)
+      (VLeft e , _       ) -> throwSomeE e
+      (_       , VLeft e ) -> throwSomeE e
+      (VRight _, VRight _) -> pure ()
+
+
+-- | Throw some exception
+throwSomeE :: forall es' es a m. (Monad m, LiftVariant es' es) => V es' -> Excepts es m a
+{-# INLINABLE throwSomeE #-}
+throwSomeE = Excepts . pure . VLeft . liftVariant
diff --git a/lib/GHCup/Prelude/File.hs b/lib/GHCup/Prelude/File.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/File.hs
@@ -0,0 +1,426 @@
+{-# LANGUAGE CPP                 #-}
+{-# LANGUAGE BangPatterns        #-}
+{-# LANGUAGE DataKinds           #-}
+{-# LANGUAGE FlexibleContexts    #-}
+{-# LANGUAGE FlexibleInstances   #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE OverloadedStrings   #-}
+{-# LANGUAGE TypeFamilies        #-}
+{-# LANGUAGE TypeOperators       #-}
+
+module GHCup.Prelude.File (
+  mergeFileTree,
+  copyFileE,
+  findFilesDeep,
+  getDirectoryContentsRecursive,
+  getDirectoryContentsRecursiveBFS,
+  getDirectoryContentsRecursiveDFS,
+  getDirectoryContentsRecursiveUnsafe,
+  getDirectoryContentsRecursiveBFSUnsafe,
+  getDirectoryContentsRecursiveDFSUnsafe,
+  recordedInstallationFile,
+  module GHCup.Prelude.File.Search,
+
+  chmod_755,
+  isBrokenSymlink,
+  copyFile,
+  deleteFile,
+  install,
+  removeEmptyDirectory,
+  removeDirIfEmptyOrIsSymlink,
+  removeEmptyDirsRecursive,
+  rmFileForce,
+  createDirRecursive',
+  recyclePathForcibly,
+  rmDirectory,
+  recycleFile,
+  rmFile,
+  rmDirectoryLink,
+  moveFilePortable,
+  moveFile,
+  rmPathForcibly,
+
+  exeExt,
+  exeExt',
+  getLinkTarget,
+  pathIsLink,
+  rmLink,
+  createLink
+) where
+
+import GHCup.Utils.Dirs
+import GHCup.Prelude.Logger.Internal (logInfo, logDebug)
+import GHCup.Prelude.Internal
+import GHCup.Prelude.File.Search
+#if IS_WINDOWS
+import GHCup.Prelude.File.Windows
+import GHCup.Prelude.Windows
+#else
+import GHCup.Prelude.File.Posix
+import GHCup.Prelude.Posix
+#endif
+import           GHCup.Errors
+import           GHCup.Types
+import           GHCup.Types.Optics
+
+import           Text.Regex.Posix
+import           Control.Monad.IO.Unlift        ( MonadUnliftIO )
+import           Control.Exception.Safe
+import           Control.Monad.Reader
+import           Data.ByteString                ( ByteString )
+import           Haskus.Utils.Variant.Excepts
+import           System.FilePath
+import           Text.PrettyPrint.HughesPJClass (prettyShow)
+
+import qualified Data.Text                     as T
+import qualified Streamly.Prelude              as S
+import Control.DeepSeq (force)
+import Control.Exception (evaluate)
+import GHC.IO.Exception
+import System.IO.Error
+
+
+-- | Merge one file tree to another given a copy operation.
+--
+-- Records every successfully installed file into the destination
+-- returned by 'recordedInstallationFile'.
+--
+-- If any copy operation fails, the record file is deleted, as well
+-- as the partially installed files.
+mergeFileTree :: ( MonadMask m
+                 , S.MonadAsync m
+                 , MonadReader env m
+                 , HasDirs env
+                 , HasLog env
+                 , MonadCatch m
+                 )
+              => GHCupPath                       -- ^ source base directory from which to install findFiles
+              -> InstallDirResolved              -- ^ destination base dir
+              -> Tool
+              -> GHCTargetVersion
+              -> (FilePath -> FilePath -> m ())  -- ^ file copy operation
+              -> Excepts '[MergeFileTreeError] m ()
+mergeFileTree _ (GHCupBinDir fp) _ _ _ =
+  throwIO $ userError ("mergeFileTree: internal error, called on " <> fp)
+mergeFileTree sourceBase destBase tool v' copyOp = do
+  lift $ logInfo $ "Merging file tree from \""
+       <> T.pack (fromGHCupPath sourceBase)
+       <> "\" to \""
+       <> T.pack (fromInstallDir destBase)
+       <> "\""
+  recFile <- recordedInstallationFile tool v'
+
+  wrapInExcepts $ do
+    -- These checks are not atomic, but we perform them to have
+    -- the opportunity to abort before copying has started.
+    --
+    -- The actual copying might still fail.
+    liftIO $ baseCheck (fromGHCupPath sourceBase)
+    liftIO $ destCheck (fromInstallDir destBase)
+
+    -- we only record for non-isolated installs
+    when (isSafeDir destBase) $ do
+      whenM (liftIO $ doesFileExist recFile)
+        $ throwIO $ userError ("mergeFileTree: DB file " <> recFile <> " already exists!")
+      liftIO $ createDirectoryIfMissing True (takeDirectory recFile)
+
+  -- we want the cleanup action to leak through in case of exception
+  onE_ (cleanupOnPartialInstall recFile) $ wrapInExcepts $ do
+    logDebug "Starting merge"
+    lift $ flip S.mapM_ (getDirectoryContentsRecursive sourceBase) $ \f -> do
+      copy f
+      logDebug $ T.pack "Recording installed file: " <> T.pack f
+      recordInstalledFile f recFile
+      pure f
+
+ where
+  wrapInExcepts = handleIO (\e -> throwE $ MergeFileTreeError e (fromGHCupPath sourceBase) (fromInstallDir destBase))
+
+  cleanupOnPartialInstall recFile = when (isSafeDir destBase) $ do
+    (force -> !l) <- hideErrorDef [NoSuchThing] [] $ lines <$> liftIO
+      (readFile recFile >>= evaluate)
+    logDebug "Deleting recorded files due to partial install"
+    forM_ l $ \f -> do
+      let dest = fromInstallDir destBase </> dropDrive f
+      logDebug $ "rm -f " <> T.pack f
+      hideError NoSuchThing $ rmFile dest
+      pure ()
+    logDebug $ "rm -f " <> T.pack recFile
+    hideError NoSuchThing $ rmFile recFile
+    logDebug $ "rm -f " <> T.pack (fromInstallDir destBase)
+    hideError UnsatisfiedConstraints $ hideError NoSuchThing $
+      removeEmptyDirsRecursive (fromInstallDir destBase)
+
+
+  recordInstalledFile f recFile = when (isSafeDir destBase) $
+    liftIO $ appendFile recFile (f <> "\n")
+
+  copy source = do
+    let dest = fromInstallDir destBase </> source
+        src  = fromGHCupPath sourceBase </> source
+
+    when (isAbsolute source)
+      $ throwIO $ userError ("mergeFileTree: source file " <> source <> " is not relative!")
+
+    liftIO . createDirectoryIfMissing True . takeDirectory $ dest
+
+    copyOp src dest
+
+
+  baseCheck src = do
+      when (isRelative src)
+        $ throwIO $ userError ("mergeFileTree: source base directory " <> src <> " is not absolute!")
+      whenM (not <$> doesDirectoryExist src)
+        $ throwIO $ userError ("mergeFileTree: source base directory " <> src <> " does not exist!")
+  destCheck dest = do
+      when (isRelative dest)
+        $ throwIO $ userError ("mergeFileTree: destination base directory " <> dest <> " is not absolute!")
+
+
+
+copyFileE :: (CopyError :< xs, MonadCatch m, MonadIO m) => FilePath -> FilePath -> Bool -> Excepts xs m ()
+copyFileE from to = handleIO (throwE . CopyError . show) . liftIO . copyFile from to
+
+
+-- | List all the files in a directory and all subdirectories.
+--
+-- The order places files in sub-directories after all the files in their
+-- parent directories. The list is generated lazily so is not well defined if
+-- the source directory structure changes before the list is used.
+--
+-- depth first
+getDirectoryContentsRecursiveDFS :: (MonadCatch m, S.MonadAsync m, MonadMask m)
+                                 => GHCupPath
+                                 -> S.SerialT m FilePath
+getDirectoryContentsRecursiveDFS (fromGHCupPath -> fp) = getDirectoryContentsRecursiveDFSUnsafe fp
+
+-- breadth first
+getDirectoryContentsRecursiveBFS :: (MonadCatch m, S.MonadAsync m, MonadMask m)
+                                 => GHCupPath
+                                 -> S.SerialT m FilePath
+getDirectoryContentsRecursiveBFS (fromGHCupPath -> fp) = getDirectoryContentsRecursiveBFSUnsafe fp
+
+
+getDirectoryContentsRecursive :: (MonadCatch m, S.MonadAsync m, MonadMask m)
+                              => GHCupPath
+                              -> S.SerialT m FilePath
+getDirectoryContentsRecursive = getDirectoryContentsRecursiveBFS
+
+getDirectoryContentsRecursiveUnsafe :: (MonadCatch m, S.MonadAsync m, MonadMask m)
+                                    => FilePath
+                                    -> S.SerialT m FilePath
+getDirectoryContentsRecursiveUnsafe = getDirectoryContentsRecursiveBFSUnsafe
+
+findFilesDeep :: GHCupPath -> Regex -> IO [FilePath]
+findFilesDeep path regex =
+  S.toList $ S.filter (match regex) $ getDirectoryContentsRecursive path
+
+
+recordedInstallationFile :: ( MonadReader env m
+                            , HasDirs env
+                            )
+                         => Tool
+                         -> GHCTargetVersion
+                         -> m FilePath
+recordedInstallationFile t v' = do
+  Dirs {..}  <- getDirs
+  pure (fromGHCupPath dbDir </> prettyShow t </> T.unpack (tVerToText v'))
+
+removeDirIfEmptyOrIsSymlink :: (MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
+removeDirIfEmptyOrIsSymlink filepath =
+  hideError UnsatisfiedConstraints $
+  handleIO' InappropriateType
+        (handleIfSym filepath)
+        (liftIO $ removeEmptyDirectory filepath)
+  where
+    handleIfSym fp e = do
+      isSym <- liftIO $ pathIsSymbolicLink fp
+      if isSym
+      then rmFileForce fp
+      else liftIO $ ioError e
+
+removeEmptyDirsRecursive :: (MonadMask m, MonadIO m, MonadCatch m) => FilePath -> m ()
+removeEmptyDirsRecursive = go
+ where
+  go fp = do
+    cs <- liftIO $ listDirectory fp >>= filterM doesDirectoryExist . fmap (fp </>)
+    forM_ cs go
+    liftIO $ removeEmptyDirectory fp
+
+rmFileForce :: (MonadMask m, MonadIO m) => FilePath -> m ()
+rmFileForce filepath = do
+  hideError doesNotExistErrorType
+    $ hideError InappropriateType $ rmFile filepath
+
+-- | More permissive version of 'createDirRecursive'. This doesn't
+-- error when the destination is a symlink to a directory.
+createDirRecursive' :: FilePath -> IO ()
+createDirRecursive' p =
+  handleIO (\e -> if isAlreadyExistsError e then isSymlinkDir e else throwIO e)
+    . createDirectoryIfMissing True
+    $ p
+
+ where
+  isSymlinkDir e = do
+    ft <- pathIsSymbolicLink p
+    case ft of
+      True -> do
+        rp <- canonicalizePath p
+        rft <- doesDirectoryExist rp
+        case rft of
+          True -> pure ()
+          _ -> throwIO e
+      _ -> throwIO e
+
+
+-- https://github.com/haskell/directory/issues/110
+-- https://github.com/haskell/directory/issues/96
+-- https://www.sqlite.org/src/info/89f1848d7f
+recyclePathForcibly :: ( MonadIO m
+                       , MonadReader env m
+                       , HasDirs env
+                       , MonadMask m
+                       )
+                    => GHCupPath
+                    -> m ()
+recyclePathForcibly fp
+  | isWindows = do
+      Dirs { recycleDir } <- getDirs
+      tmp <- liftIO $ createTempGHCupDirectory recycleDir "recyclePathForcibly"
+      let dest = tmp `appendGHCupPath` takeFileName (fromGHCupPath fp)
+      liftIO (moveFile (fromGHCupPath fp) (fromGHCupPath dest))
+          `catch`
+          (\e -> if | isDoesNotExistError e -> pure ()
+                    | isPermissionError e || ioeGetErrorType e == UnsupportedOperation {- EXDEV on windows -} -> recover (liftIO $ removePathForcibly fp)
+                    | otherwise -> throwIO e)
+          `finally`
+            liftIO (handleIO (\_ -> pure ()) $ removePathForcibly tmp)
+  | otherwise = liftIO $ removePathForcibly fp
+
+
+
+rmDirectory :: (MonadIO m, MonadMask m)
+            => GHCupPath
+            -> m ()
+rmDirectory fp
+  | isWindows = recover (liftIO $ removeDirectory fp)
+  | otherwise = liftIO $ removeDirectory fp
+
+
+-- https://www.sqlite.org/src/info/89f1848d7f
+-- https://github.com/haskell/directory/issues/96
+recycleFile :: ( MonadIO m
+               , MonadMask m
+               , MonadReader env m
+               , HasDirs env
+               )
+            => FilePath
+            -> m ()
+recycleFile fp
+  | isWindows = do
+      Dirs { recycleDir } <- getDirs
+      liftIO $ whenM (doesDirectoryExist fp) $ ioError (IOError Nothing InappropriateType "recycleFile" "" Nothing (Just fp))
+      tmp <- liftIO $ createTempGHCupDirectory recycleDir "recycleFile"
+      let dest = fromGHCupPath tmp </> takeFileName fp
+      liftIO (moveFile fp dest)
+        `catch`
+          (\e -> if isPermissionError e || ioeGetErrorType e == UnsupportedOperation {- EXDEV on windows -} then recover (liftIO $ rmFile fp) else throwIO e)
+        `finally`
+          liftIO (handleIO (\_ -> pure ()) $ removePathForcibly tmp)
+  | otherwise = liftIO $ removeFile fp
+
+
+rmFile :: ( MonadIO m
+          , MonadMask m
+          )
+      => FilePath
+      -> m ()
+rmFile fp
+  | isWindows = recover (liftIO $ removeFile fp)
+  | otherwise = liftIO $ removeFile fp
+
+
+rmDirectoryLink :: (MonadIO m, MonadMask m, MonadReader env m, HasDirs env)
+                => FilePath
+                -> m ()
+rmDirectoryLink fp
+  | isWindows = recover (liftIO $ removeDirectoryLink fp)
+  | otherwise = liftIO $ removeDirectoryLink fp
+
+
+rmPathForcibly :: ( MonadIO m
+                  , MonadMask m
+                  )
+               => GHCupPath
+               -> m ()
+rmPathForcibly fp
+  | isWindows = recover (liftIO $ removePathForcibly fp)
+  | otherwise = liftIO $ removePathForcibly fp
+
+
+-- | The file extension for executables.
+exeExt :: String
+exeExt
+  | isWindows = ".exe"
+  | otherwise = ""
+
+-- | The file extension for executables.
+exeExt' :: ByteString
+exeExt'
+  | isWindows = ".exe"
+  | otherwise = ""
+
+
+rmLink :: (MonadReader env m, HasDirs env, MonadIO m, MonadMask m) => FilePath -> m ()
+rmLink fp
+  | isWindows = do
+      hideError doesNotExistErrorType . recycleFile $ fp
+      hideError doesNotExistErrorType . recycleFile $ (dropExtension fp <.> "shim")
+  | otherwise = hideError doesNotExistErrorType . recycleFile $ fp
+
+
+-- | Creates a symbolic link on unix and a fake symlink on windows for
+-- executables, which:
+--     1. is a shim exe
+--     2. has a corresponding .shim file in the same directory that
+--        contains the target
+--
+-- This overwrites previously existing files.
+--
+-- On windows, this requires that 'ensureGlobalTools' was run beforehand.
+createLink :: ( MonadMask m
+              , MonadThrow m
+              , HasLog env
+              , MonadIO m
+              , MonadReader env m
+              , HasDirs env
+              , MonadUnliftIO m
+              , MonadFail m
+              )
+           => FilePath      -- ^ path to the target executable
+           -> FilePath      -- ^ path to be created
+           -> m ()
+createLink link exe
+  | isWindows = do
+      dirs <- getDirs
+      let shimGen = fromGHCupPath (cacheDir dirs) </> "gs.exe"
+
+      let shim = dropExtension exe <.> "shim"
+          -- For hardlinks, link needs to be absolute.
+          -- If link is relative, it's relative to the target exe.
+          -- Note that (</>) drops lhs when rhs is absolute.
+          fullLink = takeDirectory exe </> link
+          shimContents = "path = " <> fullLink
+
+      logDebug $ "rm -f " <> T.pack exe
+      rmLink exe
+
+      logDebug $ "ln -s " <> T.pack fullLink <> " " <> T.pack exe
+      liftIO $ copyFile shimGen exe False
+      liftIO $ writeFile shim shimContents
+  | otherwise = do
+      logDebug $ "rm -f " <> T.pack exe
+      hideError doesNotExistErrorType $ recycleFile exe
+
+      logDebug $ "ln -s " <> T.pack link <> " " <> T.pack exe
+      liftIO $ createFileLink link exe
diff --git a/lib/GHCup/Prelude/File/Posix.hs b/lib/GHCup/Prelude/File/Posix.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/File/Posix.hs
@@ -0,0 +1,324 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleContexts  #-}
+{-# LANGUAGE DataKinds  #-}
+{-# LANGUAGE MultiWayIf  #-}
+{-# LANGUAGE CApiFFI #-}
+
+{-|
+Module      : GHCup.Utils.File.Posix
+Description : File and directory handling for unix
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : POSIX
+-}
+module GHCup.Prelude.File.Posix where
+
+import           GHCup.Prelude.File.Posix.Traversals
+
+import           Control.Exception.Safe
+import           Control.Monad.Reader
+import           Foreign.C.String
+import           Foreign.C.Error
+import           Foreign.C.Types
+import           System.IO                      ( hClose, hSetBinaryMode )
+import           System.IO.Error      hiding    ( catchIOError )
+import           System.FilePath
+import           System.Directory               ( removeFile, pathIsSymbolicLink, getSymbolicLinkTarget, doesPathExist )
+import           System.Posix.Directory
+import           System.Posix.Error             ( throwErrnoPathIfMinus1Retry )
+import           System.Posix.Internals         ( withFilePath )
+import           System.Posix.Files
+import           System.Posix.Types
+
+
+import qualified System.Posix.Directory        as PD
+import qualified System.Posix.Files            as PF
+import qualified System.Posix.IO               as SPI
+import qualified System.Posix as Posix
+import qualified Streamly.FileSystem.Handle    as FH
+import qualified Streamly.Internal.FileSystem.Handle
+                                               as IFH
+import qualified Streamly.Prelude              as S
+import qualified GHCup.Prelude.File.Posix.Foreign as FD
+import qualified Streamly.Internal.Data.Stream.StreamD.Type
+                                               as D
+import           Streamly.Internal.Data.Unfold.Type
+import qualified Streamly.Internal.Data.Unfold as U
+import           Streamly.Internal.Control.Concurrent ( withRunInIO )
+import           Streamly.Internal.Data.IOFinalizer   ( newIOFinalizer, runIOFinalizer )
+
+
+-- | On unix, we can use symlinks, so we just get the
+-- symbolic link target.
+--
+-- On windows, we have to emulate symlinks via shims,
+-- see 'createLink'.
+getLinkTarget :: FilePath -> IO FilePath
+getLinkTarget = getSymbolicLinkTarget
+
+
+-- | Checks whether the path is a link.
+pathIsLink :: FilePath -> IO Bool
+pathIsLink = pathIsSymbolicLink
+
+
+chmod_755 :: MonadIO m => FilePath -> m ()
+chmod_755 fp = do
+  let exe_mode =
+          nullFileMode
+            `unionFileModes` ownerExecuteMode
+            `unionFileModes` ownerReadMode
+            `unionFileModes` ownerWriteMode
+            `unionFileModes` groupExecuteMode
+            `unionFileModes` groupReadMode
+            `unionFileModes` otherExecuteMode
+            `unionFileModes` otherReadMode
+  liftIO $ setFileMode fp exe_mode
+
+
+-- |Default permissions for a new file.
+newFilePerms :: FileMode
+newFilePerms =
+  ownerWriteMode
+    `unionFileModes` ownerReadMode
+    `unionFileModes` groupWriteMode
+    `unionFileModes` groupReadMode
+    `unionFileModes` otherWriteMode
+    `unionFileModes` otherReadMode
+
+
+-- | Checks whether the binary is a broken link.
+isBrokenSymlink :: FilePath -> IO Bool
+isBrokenSymlink fp = do
+  try (pathIsSymbolicLink fp) >>= \case
+    Right True -> do
+      let symDir = takeDirectory fp
+      tfp <- getSymbolicLinkTarget fp
+      not <$> doesPathExist
+        -- this drops 'symDir' if 'tfp' is absolute
+        (symDir </> tfp)
+    Right b -> pure b
+    Left e | isDoesNotExistError e -> pure False
+           | otherwise -> throwIO e
+
+copyFile :: FilePath   -- ^ source file
+         -> FilePath   -- ^ destination file
+         -> Bool       -- ^ fail if file exists
+         -> IO ()
+copyFile from to fail' = do
+  bracket
+    (openFdHandle from SPI.ReadOnly [FD.oNofollow] Nothing)
+    (hClose . snd)
+    $ \(fromFd, fH) -> do
+        sourceFileMode <- fileMode <$> getFdStatus fromFd
+        let dflags = [ FD.oNofollow
+                     , if fail' then FD.oExcl else FD.oTrunc
+                     ]
+        bracket
+          (openFdHandle to SPI.WriteOnly dflags $ Just sourceFileMode)
+          (hClose . snd)
+          $ \(_, tH) -> do
+              hSetBinaryMode fH True
+              hSetBinaryMode tH True
+              streamlyCopy (fH, tH)
+ where
+  openFdHandle fp omode flags fM = do
+    fd      <- openFd' fp omode flags fM
+    handle' <- SPI.fdToHandle fd
+    pure (fd, handle')
+  streamlyCopy (fH, tH) =
+    S.fold (FH.writeChunks tH) $ IFH.toChunksWithBufferOf (256 * 1024) fH
+
+foreign import capi unsafe "fcntl.h open"
+   c_open :: CString -> CInt -> Posix.CMode -> IO CInt
+
+
+open_  :: CString
+       -> Posix.OpenMode
+       -> [FD.Flags]
+       -> Maybe Posix.FileMode
+       -> IO Posix.Fd
+open_ str how optional_flags maybe_mode = do
+    fd <- c_open str all_flags mode_w
+    return (Posix.Fd fd)
+  where
+    all_flags  = FD.unionFlags $ optional_flags ++ [open_mode] ++ creat
+
+
+    (creat, mode_w) = case maybe_mode of
+                        Nothing -> ([],0)
+                        Just x  -> ([FD.oCreat], x)
+
+    open_mode = case how of
+                   Posix.ReadOnly  -> FD.oRdonly
+                   Posix.WriteOnly -> FD.oWronly
+                   Posix.ReadWrite -> FD.oRdwr
+
+
+-- |Open and optionally create this file. See 'System.Posix.Files'
+-- for information on how to use the 'FileMode' type.
+--
+-- Note that passing @Just x@ as the 4th argument triggers the
+-- `oCreat` status flag, which must be set when you pass in `oExcl`
+-- to the status flags. Also see the manpage for @open(2)@.
+openFd' :: FilePath
+        -> Posix.OpenMode
+        -> [FD.Flags]               -- ^ status flags of @open(2)@
+        -> Maybe Posix.FileMode  -- ^ @Just x@ => creates the file with the given modes, Nothing => the file must exist.
+        -> IO Posix.Fd
+openFd' name how optional_flags maybe_mode =
+   withFilePath name $ \str ->
+     throwErrnoPathIfMinus1Retry "openFd" name $
+       open_ str how optional_flags maybe_mode
+
+
+-- |Deletes the given file. Raises `eISDIR`
+-- if run on a directory. Does not follow symbolic links.
+--
+-- Throws:
+--
+--    - `InappropriateType` for wrong file type (directory)
+--    - `NoSuchThing` if the file does not exist
+--    - `PermissionDenied` if the directory cannot be read
+--
+-- Notes: calls `unlink`
+deleteFile :: FilePath -> IO ()
+deleteFile = removeLink
+
+
+-- |Recreate a symlink.
+--
+-- In `Overwrite` copy mode only files and empty directories are deleted.
+--
+-- Safety/reliability concerns:
+--
+--    * `Overwrite` mode is inherently non-atomic
+--
+-- Throws:
+--
+--    - `InvalidArgument` if source file is wrong type (not a symlink)
+--    - `PermissionDenied` if output directory cannot be written to
+--    - `PermissionDenied` if source directory cannot be opened
+--    - `SameFile` if source and destination are the same file
+--      (`HPathIOException`)
+--
+--
+-- Throws in `Strict` mode only:
+--
+--    - `AlreadyExists` if destination already exists
+--
+-- Throws in `Overwrite` mode only:
+--
+--    - `UnsatisfiedConstraints` if destination file is non-empty directory
+--
+-- Notes:
+--
+--    - calls `symlink`
+recreateSymlink :: FilePath   -- ^ the old symlink file
+                -> FilePath   -- ^ destination file
+                -> Bool       -- ^ fail if destination file exists
+                -> IO ()
+recreateSymlink symsource newsym fail' = do
+  sympoint <- readSymbolicLink symsource
+  case fail' of
+    True  -> pure ()
+    False ->
+      handleIO (\e -> if doesNotExistErrorType  == ioeGetErrorType e then pure () else liftIO . ioError $ e) $ deleteFile newsym
+  createSymbolicLink sympoint newsym
+
+
+-- copys files, recreates symlinks, fails on all other types
+install :: FilePath -> FilePath -> Bool -> IO ()
+install from to fail' = do
+  fs <- PF.getSymbolicLinkStatus from
+  decide fs
+ where
+  decide fs | PF.isRegularFile fs     = copyFile from to fail'
+            | PF.isSymbolicLink fs    = recreateSymlink from to fail'
+            | otherwise               = ioError $ mkIOError illegalOperationErrorType "install: not a regular file or symlink" Nothing (Just from)
+
+moveFile :: FilePath -> FilePath -> IO ()
+moveFile = rename
+
+
+moveFilePortable :: FilePath -> FilePath -> IO ()
+moveFilePortable from to = do
+  catchErrno [eXDEV] (moveFile from to) $ do
+    copyFile from to True
+    removeFile from
+
+
+catchErrno :: [Errno] -- ^ errno to catch
+           -> IO a    -- ^ action to try, which can raise an IOException
+           -> IO a    -- ^ action to carry out in case of an IOException and
+                      --   if errno matches
+           -> IO a
+catchErrno en a1 a2 =
+  catchIOError a1 $ \e -> do
+    errno <- getErrno
+    if errno `elem` en
+      then a2
+      else ioError e
+
+removeEmptyDirectory :: FilePath -> IO ()
+removeEmptyDirectory = PD.removeDirectory
+
+
+-- | Create an 'Unfold' of directory contents.
+unfoldDirContents :: (MonadMask m, MonadIO m, S.MonadAsync m) => Unfold m FilePath (FD.DirType, FilePath)
+unfoldDirContents = U.bracket (liftIO . openDirStream) (liftIO . closeDirStream) (Unfold step return)
+ where
+  {-# INLINE [0] step #-}
+  step dirstream = do
+    (typ, e) <- liftIO $ readDirEnt dirstream
+    return $ if
+      | null e    -> D.Stop
+      | "." == e  -> D.Skip dirstream
+      | ".." == e -> D.Skip dirstream
+      | otherwise -> D.Yield (typ, e) dirstream
+
+
+getDirectoryContentsRecursiveDFSUnsafe :: (MonadMask m, MonadIO m, S.MonadAsync m)
+                                       => FilePath
+                                       -> S.SerialT m FilePath
+getDirectoryContentsRecursiveDFSUnsafe fp = go ""
+ where
+  go cd = flip S.concatMap (S.unfold unfoldDirContents (fp </> cd)) $ \(t, f) ->
+    if | t == FD.dtDir -> go (cd </> f)
+       | otherwise     -> pure (cd </> f)
+
+
+getDirectoryContentsRecursiveUnfold :: (MonadMask m, MonadIO m, S.MonadAsync m) => Unfold m FilePath FilePath
+getDirectoryContentsRecursiveUnfold = Unfold step (\s -> return (s, Nothing, [""]))
+ where
+  {-# INLINE [0] step #-}
+  step (_, Nothing, []) = return D.Stop
+
+  step (topdir, Just (cdir, dirstream, finalizer), dirs) = flip onException (runIOFinalizer finalizer) $ do
+    (dt, f) <- liftIO $ readDirEnt dirstream
+    if | FD.dtUnknown == dt -> do
+           runIOFinalizer finalizer
+           return $ D.Skip (topdir, Nothing, dirs)
+       | f == "." || f == ".."
+                        -> return $ D.Skip               (topdir, Just (cdir, dirstream, finalizer), dirs)
+       | FD.dtDir == dt -> return $ D.Skip               (topdir, Just (cdir, dirstream, finalizer), (cdir </> f):dirs)
+       | otherwise      -> return $ D.Yield (cdir </> f) (topdir, Just (cdir, dirstream, finalizer), dirs)
+
+  step (topdir, Nothing, dir:dirs) = do
+    (s, f) <- acquire (topdir </> dir)
+    return $ D.Skip (topdir, Just (dir, s, f), dirs)
+
+  acquire dir =
+    withRunInIO $ \run -> mask_ $ run $ do
+        dirstream <- liftIO $ openDirStream dir
+        ref <- newIOFinalizer (liftIO $ closeDirStream dirstream)
+        return (dirstream, ref)
+
+getDirectoryContentsRecursiveBFSUnsafe :: (MonadMask m, MonadIO m, S.MonadAsync m)
+                                       => FilePath
+                                       -> S.SerialT m FilePath
+getDirectoryContentsRecursiveBFSUnsafe = S.unfold getDirectoryContentsRecursiveUnfold
+
+
diff --git a/lib/GHCup/Prelude/File/Posix/Foreign.hsc b/lib/GHCup/Prelude/File/Posix/Foreign.hsc
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/File/Posix/Foreign.hsc
@@ -0,0 +1,58 @@
+{-# LANGUAGE PatternSynonyms #-}
+
+module GHCup.Prelude.File.Posix.Foreign where
+
+import Data.Bits
+import Data.List (foldl')
+import Foreign.C.Types
+
+#include <limits.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+newtype DirType = DirType Int deriving (Eq, Show)
+data Flags = Flags Int | UnsupportedFlag String deriving (Eq, Show)
+
+unFlags :: Flags -> Int
+unFlags (Flags i) = i
+unFlags (UnsupportedFlag name) = error (name ++ " is not supported on this platform")
+
+-- |Returns @True@ if posix-paths was compiled with support for the provided
+-- flag. (As of this writing, the only flag for which this check may be
+-- necessary is 'oCloexec'; all other flags will always yield @True@.)
+isSupported :: Flags -> Bool
+isSupported (Flags _) = True
+isSupported _ = False
+
+-- |@O_CLOEXEC@ is not supported on every POSIX platform. Use
+-- @'isSupported' oCloexec@ to determine if support for @O_CLOEXEC@ was
+-- compiled into your version of posix-paths. (If not, using @oCloexec@ will
+-- throw an exception.)
+oCloexec :: Flags
+#ifdef O_CLOEXEC
+oCloexec = Flags #{const O_CLOEXEC}
+#else
+{-# WARNING oCloexec
+    "This version of posix-paths was compiled without @O_CLOEXEC@ support." #-}
+oCloexec = UnsupportedFlag "O_CLOEXEC"
+#endif
+
+
+
+-- If these enum declarations occur earlier in the file, haddock
+-- gets royally confused about the above doc comments.
+-- Probably http://trac.haskell.org/haddock/ticket/138
+
+#{enum DirType, DirType, DT_BLK, DT_CHR, DT_DIR, DT_FIFO, DT_LNK, DT_REG, DT_SOCK, DT_UNKNOWN}
+
+#{enum Flags, Flags, O_APPEND, O_ASYNC, O_CREAT, O_DIRECTORY, O_EXCL, O_NOCTTY, O_NOFOLLOW, O_NONBLOCK, O_RDONLY, O_WRONLY, O_RDWR, O_SYNC, O_TRUNC}
+
+pathMax :: Int
+pathMax = #{const PATH_MAX}
+
+unionFlags :: [Flags] -> CInt
+unionFlags = fromIntegral . foldl' ((. unFlags) . (.|.)) 0
+
diff --git a/lib/GHCup/Prelude/File/Posix/Traversals.hs b/lib/GHCup/Prelude/File/Posix/Traversals.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/File/Posix/Traversals.hs
@@ -0,0 +1,92 @@
+{-# LANGUAGE CApiFFI #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE ForeignFunctionInterface #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ViewPatterns #-}
+
+{-# OPTIONS_GHC -Wall #-}
+
+
+module GHCup.Prelude.File.Posix.Traversals (
+-- lower-level stuff
+  readDirEnt
+, unpackDirStream
+) where
+
+
+#if __GLASGOW_HASKELL__ < 710
+import Control.Applicative ((<$>))
+#endif
+import GHCup.Prelude.File.Posix.Foreign
+
+import Unsafe.Coerce (unsafeCoerce)
+import Foreign.C.Error
+import Foreign.C.String
+import Foreign.C.Types
+import Foreign.Ptr
+import Foreign.Storable
+import System.Posix
+import Foreign (alloca)
+import System.Posix.Internals (peekFilePath)
+
+
+
+
+
+----------------------------------------------------------
+-- dodgy stuff
+
+type CDir = ()
+type CDirent = ()
+
+-- Posix doesn't export DirStream, so to re-use that type we need to use
+-- unsafeCoerce.  It's just a newtype, so this is a legitimate usage.
+-- ugly trick.
+unpackDirStream :: DirStream -> Ptr CDir
+unpackDirStream = unsafeCoerce
+
+-- the __hscore_* functions are defined in the unix package.  We can import them and let
+-- the linker figure it out.
+foreign import ccall unsafe "__hscore_readdir"
+  c_readdir  :: Ptr CDir -> Ptr (Ptr CDirent) -> IO CInt
+
+foreign import ccall unsafe "__hscore_free_dirent"
+  c_freeDirEnt  :: Ptr CDirent -> IO ()
+
+foreign import ccall unsafe "__hscore_d_name"
+  c_name :: Ptr CDirent -> IO CString
+
+foreign import ccall unsafe "__posixdir_d_type"
+  c_type :: Ptr CDirent -> IO DirType
+
+----------------------------------------------------------
+-- less dodgy but still lower-level
+
+
+readDirEnt :: DirStream -> IO (DirType, FilePath)
+readDirEnt (unpackDirStream -> dirp) =
+  alloca $ \ptr_dEnt  -> loop ptr_dEnt
+ where
+  loop ptr_dEnt = do
+    resetErrno
+    r <- c_readdir dirp ptr_dEnt
+    if r == 0
+       then do
+         dEnt <- peek ptr_dEnt
+         if dEnt == nullPtr
+            then return (dtUnknown, mempty)
+            else do
+                 dName <- c_name dEnt >>= peekFilePath
+                 dType <- c_type dEnt
+                 c_freeDirEnt dEnt
+                 return (dType, dName)
+       else do
+         errno <- getErrno
+         if errno == eINTR
+            then loop ptr_dEnt
+            else do
+                 let (Errno eo) = errno
+                 if eo == 0
+                    then return (dtUnknown, mempty)
+                    else throwErrno "readDirEnt"
+
diff --git a/lib/GHCup/Prelude/File/Search.hs b/lib/GHCup/Prelude/File/Search.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/File/Search.hs
@@ -0,0 +1,115 @@
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleContexts  #-}
+
+module GHCup.Prelude.File.Search (
+  module GHCup.Prelude.File.Search
+  , ProcessError(..)
+  , CapturedProcess(..)
+  ) where
+
+import           GHCup.Types(ProcessError(..), CapturedProcess(..))
+
+import           Control.Monad.Reader
+import           Data.Maybe
+import           Data.Text               ( Text )
+import           Data.Void
+import           GHC.IO.Exception
+import           System.Directory hiding ( removeDirectory
+                                         , removeDirectoryRecursive
+                                         , removePathForcibly
+                                         , findFiles
+                                         )
+import           System.FilePath
+import           Text.Regex.Posix
+
+
+import qualified Data.Text                     as T
+import qualified Text.Megaparsec               as MP
+import Control.Exception.Safe (handleIO)
+import System.Directory.Internal.Prelude (ioeGetErrorType)
+
+
+
+-- | Search for a file in the search paths.
+--
+-- Catches `PermissionDenied` and `NoSuchThing` and returns `Nothing`.
+searchPath :: [FilePath] -> FilePath -> IO (Maybe FilePath)
+searchPath paths needle = go paths
+ where
+  go [] = pure Nothing
+  go (x : xs) =
+    handleIO (\e -> if ioeGetErrorType e `elem` [InappropriateType, PermissionDenied, NoSuchThing] then go xs else ioError e)
+      $ do
+          contents <- listDirectory x
+          findM (isMatch x) contents >>= \case
+            Just _ -> pure $ Just (x </> needle)
+            Nothing -> go xs
+  isMatch basedir p = do
+    if p == needle
+      then isExecutable (basedir </> needle)
+      else pure False
+
+  isExecutable :: FilePath -> IO Bool
+  isExecutable file = executable <$> getPermissions file
+
+  -- TODO: inlined from GHCup.Prelude
+  findM ~p = foldr (\x -> ifM (p x) (pure $ Just x)) (pure Nothing)
+  ifM ~b ~t ~f = do
+    b' <- b
+    if b' then t else f
+
+
+-- | Check wether a binary is shadowed by another one that comes before
+-- it in PATH. Returns the path to said binary, if any.
+isShadowed :: FilePath -> IO (Maybe FilePath)
+isShadowed p = do
+  let dir = takeDirectory p
+  let fn = takeFileName p
+  spaths <- liftIO getSearchPath
+  if dir `elem` spaths
+  then do
+    let shadowPaths = takeWhile (/= dir) spaths
+    searchPath shadowPaths fn
+  else pure Nothing
+
+
+-- | Check whether the binary is in PATH. This returns only `True`
+-- if the directory containing the binary is part of PATH.
+isInPath :: FilePath -> IO Bool
+isInPath p = do
+  let dir = takeDirectory p
+  let fn = takeFileName p
+  spaths <- liftIO getSearchPath
+  if dir `elem` spaths
+  then isJust <$> searchPath [dir] fn
+  else pure False
+
+
+-- | Follows the first match in case of Regex.
+expandFilePath :: [Either FilePath Regex] -> IO [FilePath]
+expandFilePath = go ""
+ where
+  go :: FilePath -> [Either FilePath Regex] -> IO [FilePath]
+  go p [] = pure [p]
+  go p (x:xs) = do
+    case x of
+      Left s -> go (p </> s) xs
+      Right regex -> do
+        fps <- findFiles p regex
+        res <- forM fps $ \fp -> go (p </> fp) xs
+        pure $ mconcat res
+
+
+findFiles :: FilePath -> Regex -> IO [FilePath]
+findFiles path regex = do
+  contents <- listDirectory path
+  pure $ filter (match regex) contents
+
+
+findFiles' :: FilePath -> MP.Parsec Void Text a -> IO [FilePath]
+findFiles' path parser = do
+  contents <- listDirectory path
+  pure $ filter (\fp -> either (const False) (const True) $ MP.parse parser "" (T.pack fp)) contents
+
+
diff --git a/lib/GHCup/Prelude/File/Windows.hs b/lib/GHCup/Prelude/File/Windows.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/File/Windows.hs
@@ -0,0 +1,311 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleContexts  #-}
+{-# LANGUAGE DataKinds  #-}
+
+{-|
+Module      : GHCup.Utils.File.Windows
+Description : File and directory handling for windows
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : Windows
+-}
+module GHCup.Prelude.File.Windows where
+
+import           GHCup.Utils.Dirs
+import           GHCup.Prelude.Internal
+
+import           Control.Exception.Safe
+import           Control.Monad
+import           Control.Monad.Reader
+import           Data.List
+import qualified GHC.Unicode                  as U
+import           System.FilePath
+import qualified System.IO.Error              as IOE
+
+import qualified System.Win32.Info             as WS
+import qualified System.Win32.File             as WS
+
+import qualified Streamly.Internal.Data.Stream.StreamD.Type
+                                               as D
+import           Streamly.Internal.Data.Unfold.Type hiding ( concatMap )
+import           Data.Bits ((.&.))
+import qualified Streamly.Prelude              as S
+import qualified Streamly.Internal.Data.Unfold as U
+import           Streamly.Internal.Control.Concurrent ( withRunInIO )
+import           Streamly.Internal.Data.IOFinalizer   ( newIOFinalizer, runIOFinalizer )
+
+
+
+-- | On unix, we can use symlinks, so we just get the
+-- symbolic link target.
+--
+-- On windows, we have to emulate symlinks via shims,
+-- see 'createLink'.
+getLinkTarget :: FilePath -> IO FilePath
+getLinkTarget fp = do
+  content <- readFile (dropExtension fp <.> "shim")
+  [p] <- pure . filter ("path = " `isPrefixOf`) . lines $ content
+  pure $ stripNewline $ dropPrefix "path = " p
+
+
+-- | Checks whether the path is a link.
+pathIsLink :: FilePath -> IO Bool
+pathIsLink fp = doesPathExist (dropExtension fp <.> "shim")
+
+
+
+chmod_755 :: MonadIO m => FilePath -> m ()
+chmod_755 fp =
+  let perm = setOwnerWritable True emptyPermissions
+  in liftIO $ setPermissions fp perm
+
+
+-- | Checks whether the binary is a broken link.
+isBrokenSymlink :: FilePath -> IO Bool
+isBrokenSymlink fp = do
+  b <- pathIsLink fp
+  if b
+  then do
+    tfp <- getLinkTarget fp
+    not <$> doesPathExist
+      -- this drops 'symDir' if 'tfp' is absolute
+      (takeDirectory fp </> tfp)
+  else pure False
+
+
+copyFile :: FilePath   -- ^ source file
+         -> FilePath   -- ^ destination file
+         -> Bool       -- ^ fail if file exists
+         -> IO ()
+copyFile = WS.copyFile
+
+deleteFile :: FilePath -> IO ()
+deleteFile = WS.deleteFile
+
+
+install :: FilePath -> FilePath -> Bool -> IO ()
+install = copyFile
+
+
+moveFile :: FilePath -> FilePath -> IO ()
+moveFile from to = WS.moveFileEx from (Just to) 0
+
+
+moveFilePortable :: FilePath -> FilePath -> IO ()
+moveFilePortable = WS.moveFile
+
+
+removeEmptyDirectory :: FilePath -> IO ()
+removeEmptyDirectory = WS.removeDirectory
+
+
+unfoldDirContents :: (S.MonadAsync m, MonadIO m, MonadCatch m, MonadMask m) => Unfold m FilePath (WS.FileAttributeOrFlag, FilePath)
+unfoldDirContents = U.bracket alloc dealloc (Unfold step return)
+ where
+  {-# INLINE [0] step #-}
+  step (_, False, _, _) = return D.Stop
+  step (topdir, True, h, fd) = flip onException (liftIO $ WS.findClose h) $ do
+    f <- liftIO $ WS.getFindDataFileName fd
+    more <- liftIO $ WS.findNextFile h fd
+
+    -- can't get file attribute from FindData yet (needs Win32 PR)
+    fattr <- liftIO $ WS.getFileAttributes (topdir </> f)
+
+    if | f == "." || f == ".." -> return $ D.Skip             (topdir, more, h, fd)
+       | otherwise             -> return $ D.Yield (fattr, f) (topdir, more, h, fd)
+
+  alloc topdir = do
+    query <- liftIO $ furnishPath (topdir </> "*")
+    (h, fd) <- liftIO $ WS.findFirstFile query
+    pure (topdir, True, h, fd)
+
+  dealloc (_, _, fd, _) = liftIO $ WS.findClose fd
+
+
+getDirectoryContentsRecursiveDFSUnsafe :: (MonadCatch m, S.MonadAsync m, MonadMask m, S.IsStream t)
+                                       => FilePath
+                                       -> t m FilePath
+getDirectoryContentsRecursiveDFSUnsafe fp = go ""
+ where
+  isDir attrs = attrs .&. WS.fILE_ATTRIBUTE_DIRECTORY /= 0
+
+  go cd = flip S.concatMap (S.unfold unfoldDirContents (fp </> cd)) $ \(t, f) ->
+    if | isDir t   -> go (cd </> f)
+       | otherwise -> pure (cd </> f)
+
+
+getDirectoryContentsRecursiveUnfold :: (MonadCatch m, S.MonadAsync m, MonadMask m) => Unfold m FilePath FilePath
+getDirectoryContentsRecursiveUnfold = Unfold step init'
+ where
+  {-# INLINE [0] step #-}
+  step (_, Nothing, []) = return D.Stop
+
+  step (topdir, state@(Just (cdir, (h, findData, ref))), dirs) = flip onException (runIOFinalizer ref) $ do
+    f <- liftIO $ WS.getFindDataFileName findData
+
+    more <- liftIO $ WS.findNextFile h findData
+    when (not more) $ runIOFinalizer ref
+    let nextState = if more then state else Nothing
+
+    -- can't get file attribute from FindData yet (needs Win32 PR)
+    fattr <- liftIO $ WS.getFileAttributes (topdir </> cdir </> f)
+
+    if | f == "." || f == ".." -> return $ D.Skip               (topdir, nextState, dirs)
+       | isDir fattr           -> return $ D.Skip               (topdir, nextState, (cdir </> f):dirs)
+       | otherwise             -> return $ D.Yield (cdir </> f) (topdir, nextState, dirs)
+
+  step (topdir, Nothing, dir:dirs) = do
+    (h, findData, ref) <- acquire (topdir </> dir)
+    return $ D.Skip (topdir, Just (dir, (h, findData, ref)), dirs)
+
+  init' topdir = do
+    (h, findData, ref) <- acquire topdir
+    return (topdir, Just ("", (h, findData, ref)), [])
+
+  isDir attrs = attrs .&. WS.fILE_ATTRIBUTE_DIRECTORY /= 0
+
+  acquire dir = do
+    query <- liftIO $ furnishPath (dir </> "*")
+    withRunInIO $ \run -> mask_ $ run $ do
+        (h, findData) <- liftIO $ WS.findFirstFile query
+        ref <- newIOFinalizer (liftIO $ WS.findClose h)
+        return (h, findData, ref)
+
+
+getDirectoryContentsRecursiveBFSUnsafe :: (MonadMask m, MonadIO m, S.MonadAsync m)
+                                       => FilePath
+                                       -> S.SerialT m FilePath
+getDirectoryContentsRecursiveBFSUnsafe = S.unfold getDirectoryContentsRecursiveUnfold
+
+
+
+    --------------------------------------
+    --[ Inlined from directory package ]--
+    --------------------------------------
+
+
+furnishPath :: FilePath -> IO FilePath
+furnishPath path =
+  (toExtendedLengthPath <$> rawPrependCurrentDirectory path)
+    `IOE.catchIOError` \ _ ->
+      pure path
+
+
+toExtendedLengthPath :: FilePath -> FilePath
+toExtendedLengthPath path
+  | isRelative path = simplifiedPath
+  | otherwise =
+      case simplifiedPath of
+        '\\' : '?'  : '?' : '\\' : _ -> simplifiedPath
+        '\\' : '\\' : '?' : '\\' : _ -> simplifiedPath
+        '\\' : '\\' : '.' : '\\' : _ -> simplifiedPath
+        '\\' : subpath@('\\' : _) -> "\\\\?\\UNC" <> subpath
+        _ -> "\\\\?\\" <> simplifiedPath
+  where simplifiedPath = simplify path
+
+
+simplify :: FilePath -> FilePath
+simplify = simplifyWindows
+
+simplifyWindows :: FilePath -> FilePath
+simplifyWindows "" = ""
+simplifyWindows path =
+  case drive' of
+    "\\\\?\\" -> drive' <> subpath
+    _ -> simplifiedPath
+  where
+    simplifiedPath = joinDrive drive' subpath'
+    (drive, subpath) = splitDrive path
+    drive' = upperDrive (normaliseTrailingSep (normalisePathSeps drive))
+    subpath' = appendSep . avoidEmpty . prependSep . joinPath .
+               stripPardirs . expandDots . skipSeps .
+               splitDirectories $ subpath
+
+    upperDrive d = case d of
+      c : ':' : s | U.isAlpha c && all isPathSeparator s -> U.toUpper c : ':' : s
+      _ -> d
+    skipSeps = filter (not . (`elem` (pure <$> pathSeparators)))
+    stripPardirs | pathIsAbsolute || subpathIsAbsolute = dropWhile (== "..")
+                 | otherwise = id
+    prependSep | subpathIsAbsolute = (pathSeparator :)
+               | otherwise = id
+    avoidEmpty | not pathIsAbsolute
+                 && (null drive || hasTrailingPathSep) -- prefer "C:" over "C:."
+                 = emptyToCurDir
+               | otherwise = id
+    appendSep p | hasTrailingPathSep
+                  && not (pathIsAbsolute && null p)
+                  = addTrailingPathSeparator p
+                | otherwise = p
+    pathIsAbsolute = not (isRelative path)
+    subpathIsAbsolute = any isPathSeparator (take 1 subpath)
+    hasTrailingPathSep = hasTrailingPathSeparator subpath
+
+emptyToCurDir :: FilePath -> FilePath
+emptyToCurDir ""   = "."
+emptyToCurDir path = path
+
+normaliseTrailingSep :: FilePath -> FilePath
+normaliseTrailingSep path = do
+  let path' = reverse path
+  let (sep, path'') = span isPathSeparator path'
+  let addSep = if null sep then id else (pathSeparator :)
+  reverse (addSep path'')
+
+normalisePathSeps :: FilePath -> FilePath
+normalisePathSeps p = (\ c -> if isPathSeparator c then pathSeparator else c) <$> p
+
+expandDots :: [FilePath] -> [FilePath]
+expandDots = reverse . go []
+  where
+    go ys' xs' =
+      case xs' of
+        [] -> ys'
+        x : xs ->
+          case x of
+            "." -> go ys' xs
+            ".." ->
+              case ys' of
+                [] -> go (x : ys') xs
+                ".." : _ -> go (x : ys') xs
+                _ : ys -> go ys xs
+            _ -> go (x : ys') xs
+
+rawPrependCurrentDirectory :: FilePath -> IO FilePath
+rawPrependCurrentDirectory path
+  | isRelative path =
+    ((`ioeAddLocation` "prependCurrentDirectory") .
+     (`IOE.ioeSetFileName` path)) `IOE.modifyIOError` do
+      getFullPathName path
+  | otherwise = pure path
+
+ioeAddLocation :: IOError -> String -> IOError
+ioeAddLocation e loc = do
+  IOE.ioeSetLocation e newLoc
+  where
+    newLoc = loc <> if null oldLoc then "" else ":" <> oldLoc
+    oldLoc = IOE.ioeGetLocation e
+
+getFullPathName :: FilePath -> IO FilePath
+getFullPathName path =
+  fromExtendedLengthPath <$> WS.getFullPathName (toExtendedLengthPath path)
+
+fromExtendedLengthPath :: FilePath -> FilePath
+fromExtendedLengthPath ePath =
+  case ePath of
+    '\\' : '\\' : '?' : '\\' : path ->
+      case path of
+        'U' : 'N' : 'C' : subpath@('\\' : _) -> "\\" <> subpath
+        drive : ':' : subpath
+          -- if the path is not "regular", then the prefix is necessary
+          -- to ensure the path is interpreted literally
+          | U.isAlpha drive && U.isAscii drive && isPathRegular subpath -> path
+        _ -> ePath
+    _ -> ePath
+  where
+    isPathRegular path =
+      not ('/' `elem` path ||
+           "." `elem` splitDirectories path ||
+           ".." `elem` splitDirectories path)
diff --git a/lib/GHCup/Prelude/Internal.hs b/lib/GHCup/Prelude/Internal.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Internal.hs
@@ -0,0 +1,519 @@
+{-# LANGUAGE CPP                 #-}
+{-# LANGUAGE DataKinds           #-}
+{-# LANGUAGE FlexibleContexts    #-}
+{-# LANGUAGE FlexibleInstances   #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeFamilies        #-}
+{-# LANGUAGE TypeOperators       #-}
+
+{-|
+Module      : GHCup.Prelude.Internal
+Description : MegaParsec utilities
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+
+Stuff that doesn't need GHCup modules, so we can avoid
+recursive imports.
+-}
+module GHCup.Prelude.Internal where
+
+
+import           Control.Applicative
+import           Control.Exception.Safe
+import           Control.Monad
+import           Control.Monad.IO.Class
+import           Control.Monad.Reader
+import           Data.Bifunctor
+import           Data.ByteString                ( ByteString )
+import           Data.List                      ( intercalate, stripPrefix, isPrefixOf, dropWhileEnd )
+import           Data.Maybe
+import           Data.String
+import           Data.Text                      ( Text )
+import           Data.Versions
+import           Data.Word8                  hiding ( isDigit )
+import           Haskus.Utils.Types.List
+import           Haskus.Utils.Variant.Excepts
+import           System.IO.Error
+
+import           Control.Retry
+import           GHC.IO.Exception
+
+import qualified Data.ByteString               as B
+import qualified Data.ByteString.Lazy          as L
+import qualified Data.Strict.Maybe             as S
+import qualified Data.List.Split               as Split
+import qualified Data.Text                     as T
+import qualified Data.Text.Encoding            as E
+import qualified Data.Text.Encoding.Error      as E
+import qualified Data.Text.Lazy                as TL
+import qualified Data.Text.Lazy.Builder        as B
+import qualified Data.Text.Lazy.Builder.Int    as B
+import qualified Data.Text.Lazy.Encoding       as TLE
+
+
+
+-- $setup
+-- >>> import Data.ByteString.Internal (c2w, w2c)
+-- >>> import Test.QuickCheck
+-- >>> import Data.Word8
+-- >>> import qualified Data.Text as T
+-- >>> import qualified Data.Char as C
+-- >>> import Data.List
+-- >>> instance Arbitrary T.Text where arbitrary = T.pack <$> arbitrary
+
+
+fS :: IsString a => String -> a
+fS = fromString
+
+fromStrictMaybe :: S.Maybe a -> Maybe a
+fromStrictMaybe = S.maybe Nothing Just
+
+fSM :: S.Maybe a -> Maybe a
+fSM = fromStrictMaybe
+
+toStrictMaybe :: Maybe a -> S.Maybe a
+toStrictMaybe = maybe S.Nothing S.Just
+
+tSM :: Maybe a -> S.Maybe a
+tSM = toStrictMaybe
+
+internalError :: String -> IO a
+internalError = fail . ("Internal error: " <>)
+
+iE :: String -> IO a
+iE = internalError
+
+
+showT :: Show a => a -> Text
+showT = fS . show
+
+-- | Like 'when', but where the test can be monadic.
+whenM :: Monad m => m Bool -> m () -> m ()
+whenM ~b ~t = ifM b t (return ())
+
+-- | Like 'unless', but where the test can be monadic.
+unlessM :: Monad m => m Bool -> m () -> m ()
+unlessM ~b ~f = ifM b (return ()) f
+
+-- | Like @if@, but where the test can be monadic.
+ifM :: Monad m => m Bool -> m a -> m a -> m a
+ifM ~b ~t ~f = do
+  b' <- b
+  if b' then t else f
+
+whileM :: Monad m => m a -> (a -> m Bool) -> m a
+whileM ~action ~f = do
+  a  <- action
+  b' <- f a
+  if b' then whileM action f else pure a
+
+whileM_ :: Monad m => m a -> (a -> m Bool) -> m ()
+whileM_ ~action = void . whileM action
+
+guardM :: (Monad m, Alternative m) => m Bool -> m ()
+guardM ~f = guard =<< f
+
+
+handleIO' :: (MonadIO m, MonadCatch m)
+          => IOErrorType
+          -> (IOException -> m a)
+          -> m a
+          -> m a
+handleIO' err handler = handleIO
+  (\e -> if err == ioeGetErrorType e then handler e else liftIO $ ioError e)
+
+
+(??) :: forall e es a m . (Monad m, e :< es) => Maybe a -> e -> Excepts es m a
+(??) m e = maybe (throwE e) pure m
+
+
+(!?) :: forall e es a m
+      . (Monad m, e :< es)
+     => m (Maybe a)
+     -> e
+     -> Excepts es m a
+(!?) em e = lift em >>= (?? e)
+
+
+lE :: forall e es a m . (Monad m, e :< es) => Either e a -> Excepts es m a
+lE = liftE . veitherToExcepts . fromEither
+
+lE' :: forall e' e es a m
+     . (Monad m, e :< es)
+    => (e' -> e)
+    -> Either e' a
+    -> Excepts es m a
+lE' f = liftE . veitherToExcepts . fromEither . first f
+
+lEM :: forall e es a m . (Monad m, e :< es) => m (Either e a) -> Excepts es m a
+lEM em = lift em >>= lE
+
+lEM' :: forall e' e es a m
+      . (Monad m, e :< es)
+     => (e' -> e)
+     -> m (Either e' a)
+     -> Excepts es m a
+lEM' f em = lift em >>= lE . first f
+
+
+fromEither :: Either a b -> VEither '[a] b
+fromEither = either (VLeft . V) VRight
+
+
+liftIOException' :: ( MonadCatch m
+                    , MonadIO m
+                    , Monad m
+                    , e :< es'
+                    , LiftVariant es es'
+                    )
+                 => IOErrorType
+                 -> e
+                 -> Excepts es m a
+                 -> Excepts es' m a
+liftIOException' errType ex =
+  handleIO
+      (\e ->
+        if errType == ioeGetErrorType e then throwE ex else liftIO $ ioError e
+      )
+    . liftE
+
+
+liftIOException :: (MonadCatch m, MonadIO m, Monad m, e :< es')
+                => IOErrorType
+                -> e
+                -> m a
+                -> Excepts es' m a
+liftIOException errType ex =
+  handleIO
+      (\e ->
+        if errType == ioeGetErrorType e then throwE ex else liftIO $ ioError e
+      )
+    . lift
+
+
+-- | Uses safe-exceptions.
+hideError :: (MonadIO m, MonadCatch m) => IOErrorType -> m () -> m ()
+hideError err = handleIO (\e -> if err == ioeGetErrorType e then pure () else liftIO . ioError $ e)
+
+
+hideErrorDef :: (MonadIO m, MonadCatch m) => [IOErrorType] -> a -> m a -> m a
+hideErrorDef errs def =
+  handleIO (\e -> if ioeGetErrorType e `elem` errs then pure def else liftIO $ ioError e)
+
+
+hideErrorDefM :: (MonadIO m, MonadCatch m) => [IOErrorType] -> m a -> m a -> m a
+hideErrorDefM errs def =
+  handleIO (\e -> if ioeGetErrorType e `elem` errs then def else liftIO $ ioError e)
+
+
+-- TODO: does this work?
+hideExcept :: forall e es es' a m
+            . (Monad m, e :< es, LiftVariant (Remove e es) es')
+           => e
+           -> a
+           -> Excepts es m a
+           -> Excepts es' m a
+hideExcept _ a =
+  catchLiftLeft ((\_ -> pure a) :: (e -> Excepts es' m a))
+
+
+hideExcept' :: forall e es es' m
+             . (Monad m, e :< es, LiftVariant (Remove e es) es')
+            => e
+            -> Excepts es m ()
+            -> Excepts es' m ()
+hideExcept' _ =
+  catchLiftLeft ((\_ -> pure ()) :: (e -> Excepts es' m ()))
+
+
+reThrowAll :: forall e es es' a m
+            . (Monad m, e :< es')
+           => (V es -> e)
+           -> Excepts es m a
+           -> Excepts es' m a
+reThrowAll f = catchAllE (throwE . f)
+
+
+reThrowAllIO :: forall e es es' a m
+              . (MonadCatch m, Monad m, MonadIO m, e :< es')
+             => (V es -> e)
+             -> (IOException -> e)
+             -> Excepts es m a
+             -> Excepts es' m a
+reThrowAllIO f g = handleIO (throwE . g) . catchAllE (throwE . f)
+
+
+throwEither :: (Exception a, MonadThrow m) => Either a b -> m b
+throwEither a = case a of
+  Left  e -> throwM e
+  Right r -> pure r
+
+
+throwEither' :: (Exception a, MonadThrow m) => a -> Either x b -> m b
+throwEither' e eth = case eth of
+  Left  _ -> throwM e
+  Right r -> pure r
+
+throwMaybe :: (Exception a, MonadThrow m) => a -> Maybe b -> m b
+throwMaybe a m = case m of
+  Nothing -> throwM a
+  Just r -> pure r
+
+throwMaybeM :: (Exception a, MonadThrow m) => a -> m (Maybe b) -> m b
+throwMaybeM a am = do
+  m <- am
+  throwMaybe a m
+
+
+verToBS :: Version -> ByteString
+verToBS = E.encodeUtf8 . prettyVer
+
+verToS :: Version -> String
+verToS = T.unpack . prettyVer
+
+intToText :: Integral a => a -> T.Text
+intToText = TL.toStrict . B.toLazyText . B.decimal
+
+
+
+-- | Safe 'decodeUtf8With'. Replaces an invalid input byte with
+-- the Unicode replacement character U+FFFD.
+decUTF8Safe :: ByteString -> Text
+decUTF8Safe = E.decodeUtf8With E.lenientDecode
+
+decUTF8Safe' :: L.ByteString -> Text
+decUTF8Safe' = TL.toStrict . TLE.decodeUtf8With E.lenientDecode
+
+
+-- | Escape a version for use in regex
+escapeVerRex :: Version -> ByteString
+escapeVerRex = B.pack . go . B.unpack . verToBS
+ where
+  go [] = []
+  go (x : xs) | x == _period = [_backslash, _period] ++ go xs
+              | otherwise    = x : go xs
+
+
+
+recover :: (MonadIO m, MonadMask m) => m a -> m a
+recover action = 
+  recovering (fullJitterBackoff 25000 <> limitRetries 10)
+    [\_ -> Handler (\e -> pure $ isPermissionError e)
+    ,\_ -> Handler (\e -> pure (ioeGetErrorType e == InappropriateType))
+    ,\_ -> Handler (\e -> pure (ioeGetErrorType e == UnsatisfiedConstraints))
+    ]
+    (\_ -> action)
+
+
+-- | Gathering monoidal values
+--
+-- >>> traverseFold (pure . (:["0"])) ["1","2"]
+-- ["1","0","2","0"]
+-- >>> traverseFold Just ["1","2","3","4","5"]
+-- Just "12345"
+--
+-- prop> \t -> traverseFold Just t === Just (mconcat t)
+traverseFold :: (Foldable t, Applicative m, Monoid b) => (a -> m b) -> t a -> m b
+traverseFold f = foldl (\mb a -> (<>) <$> mb <*> f a) (pure mempty)
+
+-- | Gathering monoidal values
+forFold :: (Foldable t, Applicative m, Monoid b) => t a -> (a -> m b) -> m b
+forFold = \t -> (`traverseFold` t)
+
+
+-- | Strip @\\r@ and @\\n@ from 'String's
+--
+-- >>> stripNewline "foo\n\n\n"
+-- "foo"
+-- >>> stripNewline "foo\n\n\nfoo"
+-- "foofoo"
+-- >>> stripNewline "foo\r"
+-- "foo"
+-- >>> stripNewline "foo"
+-- "foo"
+--
+-- prop> \t -> stripNewline (t <> "\n") === stripNewline t
+-- prop> \t -> not (any (isNewLine . c2w) t) ==> stripNewline t == t
+stripNewline :: String -> String
+stripNewline = filter (`notElem` "\n\r")
+
+
+-- | Strip @\\r@ and @\\n@ from end of 'String'.
+--
+-- >>> stripNewlineEnd "foo\n\n\n"
+-- "foo"
+-- >>> stripNewlineEnd "foo\n\n\nfoo"
+-- "foo\n\n\nfoo"
+-- >>> stripNewlineEnd "foo\r"
+-- "foo"
+-- >>> stripNewlineEnd "foo"
+-- "foo"
+--
+-- prop> \t -> stripNewlineEnd (t <> "\n") === stripNewlineEnd t
+-- prop> \t -> not (any (isNewLine . c2w) t) ==> stripNewlineEnd t == t
+stripNewlineEnd :: String -> String
+stripNewlineEnd = dropWhileEnd (`elem` "\n\r")
+
+
+-- | Strip @\\r@ and @\\n@ from 'Text's
+--
+-- >>> stripNewline' "foo\n\n\n"
+-- "foo"
+-- >>> stripNewline' "foo\n\n\nfoo"
+-- "foofoo"
+-- >>> stripNewline' "foo\r"
+-- "foo"
+-- >>> stripNewline' "foo"
+-- "foo"
+--
+-- prop> \t -> stripNewline' (t <> "\n") === stripNewline' t
+-- prop> \t -> not (T.any (isNewLine . c2w) t) ==> stripNewline' t == t
+stripNewline' :: T.Text -> T.Text
+stripNewline' = T.filter (`notElem` "\n\r")
+
+
+-- | Is the word8 a newline?
+--
+-- >>> isNewLine (c2w '\n')
+-- True
+-- >>> isNewLine (c2w '\r')
+-- True
+--
+-- prop> \w -> w /= _lf && w /= _cr ==> not (isNewLine w)
+isNewLine :: Word8 -> Bool
+isNewLine w
+  | w == _lf = True
+  | w == _cr = True
+  | otherwise = False
+
+
+-- | Split on a PVP suffix.
+--
+-- >>> splitOnPVP "-" "ghc-iserv-dyn-9.3.20210706"
+-- ("ghc-iserv-dyn","9.3.20210706")
+-- >>> splitOnPVP "-" "ghc-iserv-dyn"
+-- ("ghc-iserv-dyn","")
+splitOnPVP :: String -> String -> (String, String)
+splitOnPVP c s = case Split.splitOn c s of
+  []  -> def
+  [_] -> def
+  xs
+    | let l = last xs
+    , (Right _) <- pvp (T.pack l) -> (intercalate c (init xs), l)
+    | otherwise -> def
+ where
+  def = (s, "")
+
+
+
+-- | Like 'find', but where the test can be monadic.
+--
+-- >>> findM (Just . C.isUpper) "teST"
+-- Just (Just 'S')
+-- >>> findM (Just . C.isUpper) "test"
+-- Just Nothing
+-- >>> findM (Just . const True) ["x",undefined]
+-- Just (Just "x")
+findM :: Monad m => (a -> m Bool) -> [a] -> m (Maybe a)
+findM ~p = foldr (\x -> ifM (p x) (pure $ Just x)) (pure Nothing)
+
+
+-- | Drops the given suffix from a list.
+--   It returns the original sequence if the sequence doesn't end with the given suffix.
+--
+-- >>> dropSuffix "!" "Hello World!"
+-- "Hello World"
+-- >>> dropSuffix "!" "Hello World!!"
+-- "Hello World!"
+-- >>> dropSuffix "!" "Hello World."
+-- "Hello World."
+dropSuffix :: Eq a => [a] -> [a] -> [a]
+dropSuffix a b = fromMaybe b $ stripSuffix a b
+
+-- | Return the prefix of the second list if its suffix
+--   matches the entire first list.
+--
+-- >>> stripSuffix "bar" "foobar"
+-- Just "foo"
+-- >>> stripSuffix ""    "baz"
+-- Just "baz"
+-- >>> stripSuffix "foo" "quux"
+-- Nothing
+stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]
+stripSuffix a b = reverse <$> stripPrefix (reverse a) (reverse b)
+
+
+-- | Drops the given prefix from a list.
+--   It returns the original sequence if the sequence doesn't start with the given prefix.
+--
+-- >>> dropPrefix "Mr. " "Mr. Men"
+-- "Men"
+-- >>> dropPrefix "Mr. " "Dr. Men"
+-- "Dr. Men"
+dropPrefix :: Eq a => [a] -> [a] -> [a]
+dropPrefix a b = fromMaybe b $ stripPrefix a b
+
+
+
+-- | Break a list into pieces separated by the first
+-- list argument, consuming the delimiter. An empty delimiter is
+-- invalid, and will cause an error to be raised.
+--
+-- >>> splitOn "\r\n" "a\r\nb\r\nd\r\ne"
+-- ["a","b","d","e"]
+-- >>> splitOn "aaa"  "aaaXaaaXaaaXaaa"
+-- ["","X","X","X",""]
+-- >>> splitOn "x"    "x"
+-- ["",""]
+-- >>> splitOn "x"    ""
+-- [""]
+--
+-- prop> \s x -> s /= "" ==> intercalate s (splitOn s x) == x
+-- prop> \c x -> splitOn [c] x                           == split (==c) x
+splitOn :: Eq a => [a] -> [a] -> [[a]]
+splitOn [] _ = error "splitOn, needle may not be empty"
+splitOn _ [] = [[]]
+splitOn needle haystack = a : if null b then [] else splitOn needle $ drop (length needle) b
+    where (a,b) = breakOn needle haystack
+
+
+-- | Splits a list into components delimited by separators,
+-- where the predicate returns True for a separator element.  The
+-- resulting components do not contain the separators.  Two adjacent
+-- separators result in an empty component in the output.
+--
+-- >>> split (== 'a') "aabbaca"
+-- ["","","bb","c",""]
+-- >>> split (== 'a') ""
+-- [""]
+-- >>> split (== ':') "::xyz:abc::123::"
+-- ["","","xyz","abc","","123","",""]
+-- >>> split (== ',') "my,list,here"
+-- ["my","list","here"]
+split :: (a -> Bool) -> [a] -> [[a]]
+split _ [] = [[]]
+split f (x:xs)
+  | f x = [] : split f xs
+  | y:ys <- split f xs = (x:y) : ys
+  | otherwise = [[]]
+
+
+-- | Find the first instance of @needle@ in @haystack@.
+-- The first element of the returned tuple
+-- is the prefix of @haystack@ before @needle@ is matched.  The second
+-- is the remainder of @haystack@, starting with the match.
+-- If you want the remainder /without/ the match, use 'stripInfix'.
+--
+-- >>> breakOn "::" "a::b::c"
+-- ("a","::b::c")
+-- >>> breakOn "/" "foobar"
+-- ("foobar","")
+--
+-- prop> \needle haystack -> let (prefix,match) = breakOn needle haystack in prefix ++ match == haystack
+breakOn :: Eq a => [a] -> [a] -> ([a], [a])
+breakOn needle haystack | needle `isPrefixOf` haystack = ([], haystack)
+breakOn _ [] = ([], [])
+breakOn needle (x:xs) = first (x:) $ breakOn needle xs
diff --git a/lib/GHCup/Prelude/Logger.hs b/lib/GHCup/Prelude/Logger.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Logger.hs
@@ -0,0 +1,61 @@
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE DataKinds        #-}
+{-# LANGUAGE OverloadedStrings   #-}
+
+{-|
+Module      : GHCup.Utils.Logger
+Description : logger definition
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+
+Here we define our main logger.
+-}
+module GHCup.Prelude.Logger
+  ( module GHCup.Prelude.Logger
+  , module GHCup.Prelude.Logger.Internal
+  )
+where
+
+import           GHCup.Prelude.Logger.Internal
+import           GHCup.Types
+import           GHCup.Types.Optics
+import           GHCup.Utils.Dirs (fromGHCupPath)
+import           GHCup.Prelude.Internal
+import           GHCup.Prelude.File.Search (findFiles)
+import           GHCup.Prelude.File (recycleFile)
+import           GHCup.Prelude.String.QQ
+
+import           Control.Exception.Safe
+import           Control.Monad
+import           Control.Monad.IO.Class
+import           Control.Monad.Reader
+import           Prelude                 hiding ( appendFile )
+import           System.FilePath
+import           System.IO.Error
+import           Text.Regex.Posix
+
+import qualified Data.ByteString               as B
+
+
+
+initGHCupFileLogging :: ( MonadReader env m
+                        , HasDirs env
+                        , MonadIO m
+                        , MonadMask m
+                        ) => m FilePath
+initGHCupFileLogging = do
+  Dirs { logsDir } <- getDirs
+  let logfile = fromGHCupPath logsDir </> "ghcup.log"
+  logFiles <- liftIO $ findFiles
+    (fromGHCupPath logsDir)
+    (makeRegexOpts compExtended
+                   execBlank
+                   ([s|^.*\.log$|] :: B.ByteString)
+    )
+  forM_ logFiles $ hideError doesNotExistErrorType . recycleFile . (fromGHCupPath logsDir </>)
+
+  liftIO $ writeFile logfile ""
+  pure logfile
diff --git a/lib/GHCup/Prelude/Logger/Internal.hs b/lib/GHCup/Prelude/Logger/Internal.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Logger/Internal.hs
@@ -0,0 +1,103 @@
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE DataKinds        #-}
+{-# LANGUAGE OverloadedStrings   #-}
+
+{-|
+Module      : GHCup.Utils.Logger.Internal
+Description : logger definition
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+
+Breaking import cycles.
+-}
+module GHCup.Prelude.Logger.Internal where
+
+import           GHCup.Types
+import           GHCup.Types.Optics
+
+import           Control.Monad
+import           Control.Monad.IO.Class
+import           Control.Monad.Reader
+import           Data.Text               ( Text )
+import           Optics
+import           Prelude                 hiding ( appendFile )
+import           System.Console.Pretty
+
+import qualified Data.Text                     as T
+
+logInfo :: ( MonadReader env m
+           , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
+           , MonadIO m
+           )
+        => Text
+        -> m ()
+logInfo = logInternal Info
+
+logWarn :: ( MonadReader env m
+           , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
+           , MonadIO m
+           )
+        => Text
+        -> m ()
+logWarn = logInternal Warn
+
+logDebug :: ( MonadReader env m
+            , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
+            , MonadIO m
+            )
+         => Text
+         -> m ()
+logDebug = logInternal Debug
+
+logError :: ( MonadReader env m
+            , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
+            , MonadIO m
+            )
+         => Text
+         -> m ()
+logError = logInternal Error
+
+
+logInternal :: ( MonadReader env m
+               , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
+               , MonadIO m
+               ) => LogLevel
+                 -> Text
+                 -> m ()
+logInternal logLevel msg = do
+  LoggerConfig {..} <- gets @"loggerConfig"
+  let color' c = if fancyColors then color c else id
+  let style' = case logLevel of
+        Debug   -> style Bold . color' Blue
+        Info    -> style Bold . color' Green
+        Warn    -> style Bold . color' Yellow
+        Error   -> style Bold . color' Red
+  let l = case logLevel of
+        Debug   -> style' "[ Debug ]"
+        Info    -> style' "[ Info  ]"
+        Warn    -> style' "[ Warn  ]"
+        Error   -> style' "[ Error ]"
+  let strs = T.split (== '\n') msg
+  let out = case strs of
+              [] -> T.empty
+              (x:xs) ->
+                  foldr (\a b -> a <> "\n" <> b) mempty
+                . ((l <> " " <> x) :)
+                . fmap (\line' -> style' "[ ...   ] " <> line' )
+                $ xs
+
+  when (lcPrintDebug || (not lcPrintDebug && (logLevel /= Debug)))
+    $ liftIO $ consoleOutter out
+
+  -- raw output
+  let lr = case logLevel of
+        Debug   -> "Debug:"
+        Info    -> "Info:"
+        Warn    -> "Warn:"
+        Error   -> "Error:"
+  let outr = lr <> " " <> msg <> "\n"
+  liftIO $ fileOutter outr
+
diff --git a/lib/GHCup/Prelude/MegaParsec.hs b/lib/GHCup/Prelude/MegaParsec.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/MegaParsec.hs
@@ -0,0 +1,124 @@
+{-# LANGUAGE CPP                  #-}
+{-# LANGUAGE OverloadedStrings    #-}
+
+{-|
+Module      : GHCup.Utils.MegaParsec
+Description : MegaParsec utilities
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+-}
+module GHCup.Prelude.MegaParsec where
+
+import           GHCup.Types
+
+import           Control.Applicative
+#if !MIN_VERSION_base(4,13,0)
+import           Control.Monad.Fail             ( MonadFail )
+#endif
+import           Data.Functor
+import           Data.Maybe
+import           Data.Text                      ( Text )
+import           Data.Versions
+import           Data.Void
+import           System.FilePath
+
+import qualified Data.List.NonEmpty            as NE
+import qualified Data.Text                     as T
+import qualified Text.Megaparsec               as MP
+
+
+choice' :: (MonadFail f, MP.MonadParsec e s f) => [f a] -> f a
+choice' []       = fail "Empty list"
+choice' [x     ] = x
+choice' (x : xs) = MP.try x <|> choice' xs
+
+
+parseUntil :: MP.Parsec Void Text a -> MP.Parsec Void Text Text
+parseUntil p = do
+  (MP.try (MP.lookAhead p) $> mempty)
+    <|> (do
+          c  <- T.singleton <$> MP.anySingle
+          c2 <- parseUntil p
+          pure (c `mappend` c2)
+        )
+
+parseUntil1 :: MP.Parsec Void Text a -> MP.Parsec Void Text Text
+parseUntil1 p = do
+  i1 <- MP.getOffset
+  t <- parseUntil p
+  i2 <- MP.getOffset
+  if i1 == i2 then fail "empty parse" else pure t
+
+
+
+-- | Parses e.g.
+--   * armv7-unknown-linux-gnueabihf-ghc
+--   * armv7-unknown-linux-gnueabihf-ghci
+ghcTargetBinP :: Text -> MP.Parsec Void Text (Maybe Text, Text)
+ghcTargetBinP t =
+  (,)
+    <$> (   MP.try
+            (Just <$> parseUntil1 (MP.chunk "-" *> MP.chunk t) <* MP.chunk "-"
+            )
+        <|> ((\ _ x -> x) Nothing <$> mempty)
+        )
+    <*> (MP.chunk t <* MP.eof)
+
+
+-- | Extracts the version from @ProjectVersion="8.10.5"@.
+ghcProjectVersion :: MP.Parsec Void Text Version
+ghcProjectVersion = do
+  _ <- MP.chunk "ProjectVersion=\""
+  ver <- parseUntil1 $ MP.chunk "\""
+  MP.setInput ver
+  version'
+
+
+-- | Extracts target triple and version from e.g.
+--   * armv7-unknown-linux-gnueabihf-8.8.3
+--   * armv7-unknown-linux-gnueabihf-8.8.3
+ghcTargetVerP :: MP.Parsec Void Text GHCTargetVersion
+ghcTargetVerP =
+  (\x y -> GHCTargetVersion x y)
+    <$> (MP.try (Just <$> parseUntil1 (MP.chunk "-" *> verP') <* MP.chunk "-")
+        <|> ((\ _ x -> x) Nothing <$> mempty)
+        )
+    <*> (version' <* MP.eof)
+ where
+  verP' :: MP.Parsec Void Text Text
+  verP' = do
+    v <- version'
+    let startsWithDigists =
+          and
+            . take 3
+            . concatMap
+              (map
+                (\case
+                  (Digits _) -> True
+                  (Str    _) -> False
+                ) . NE.toList)
+            . NE.toList
+            $ _vChunks v
+    if startsWithDigists && isNothing (_vEpoch v)
+      then pure $ prettyVer v
+      else fail "Oh"
+
+
+verP :: MP.Parsec Void Text Text -> MP.Parsec Void Text Versioning
+verP suffix = do
+  ver <- parseUntil suffix
+  if T.null ver
+    then fail "empty version"
+    else do
+      rest <- MP.getInput
+      MP.setInput ver
+      v <- versioning'
+      MP.setInput rest
+      pure v
+
+
+pathSep :: MP.Parsec Void Text Char
+pathSep = MP.oneOf pathSeparators
diff --git a/lib/GHCup/Prelude/Posix.hs b/lib/GHCup/Prelude/Posix.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Posix.hs
@@ -0,0 +1,19 @@
+module GHCup.Prelude.Posix where
+
+
+-- | Enables ANSI support on windows, does nothing on unix.
+--
+-- Returns 'Left str' on errors and 'Right bool' on success, where
+-- 'bool' markes whether ansi support was already enabled.
+--
+-- This function never crashes.
+--
+-- Rip-off of https://docs.rs/ansi_term/0.12.1/x86_64-pc-windows-msvc/src/ansi_term/windows.rs.html#10-61
+enableAnsiSupport :: IO (Either String Bool)
+enableAnsiSupport = pure (Right True)
+
+isWindows, isNotWindows :: Bool
+isWindows = False
+isNotWindows = not isWindows
+
+
diff --git a/lib/GHCup/Prelude/Process.hs b/lib/GHCup/Prelude/Process.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Process.hs
@@ -0,0 +1,25 @@
+{-# LANGUAGE CPP #-}
+
+{-|
+Module      : GHCup.Utils.Process
+Description : Process handling
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+-}
+module GHCup.Prelude.Process (
+  executeOut,
+  execLogged,
+  exec,
+  toProcessError,
+) where
+
+
+#if IS_WINDOWS
+import GHCup.Prelude.Process.Windows
+#else
+import GHCup.Prelude.Process.Posix
+#endif
+
diff --git a/lib/GHCup/Prelude/Process/Posix.hs b/lib/GHCup/Prelude/Process/Posix.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Process/Posix.hs
@@ -0,0 +1,362 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleContexts  #-}
+{-# LANGUAGE DataKinds  #-}
+{-# LANGUAGE MultiWayIf  #-}
+{-# LANGUAGE CApiFFI #-}
+
+{-|
+Module      : GHCup.Utils.File.Posix
+Description : Process handling for unix
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : POSIX
+-}
+module GHCup.Prelude.Process.Posix where
+
+import           GHCup.Utils.Dirs
+import           GHCup.Prelude.File
+import           GHCup.Prelude.File.Posix
+import           GHCup.Prelude
+import           GHCup.Prelude.Logger
+import           GHCup.Types
+import           GHCup.Types.Optics
+
+import           Control.Concurrent
+import           Control.Concurrent.Async
+import qualified Control.Exception              as E
+import           Control.Exception.Safe
+import           Control.Monad
+import           Control.Monad.Reader
+import           Control.Monad.Trans.State.Strict
+import           Data.ByteString                ( ByteString )
+import           Data.Foldable
+import           Data.IORef
+import           Data.Sequence                  ( Seq, (|>) )
+import           Data.List
+import           Data.Word8
+import           GHC.IO.Exception
+import           System.IO                      ( stderr )
+import           System.IO.Error      hiding    ( catchIOError )
+import           System.FilePath
+import           System.Posix.Directory
+import           System.Posix.IO
+import           System.Posix.Process           ( ProcessStatus(..) )
+import           System.Posix.Types
+
+
+import qualified Control.Exception             as EX
+import qualified Data.Sequence                 as Sq
+import qualified Data.Text                     as T
+import qualified Data.Text.Encoding            as E
+import qualified System.Posix.Process          as SPP
+import qualified System.Console.Terminal.Size  as TP
+import qualified Data.ByteString               as BS
+import qualified Data.ByteString.Lazy          as BL
+import qualified "unix-bytestring" System.Posix.IO.ByteString
+                                               as SPIB
+
+
+
+-- | Execute the given command and collect the stdout, stderr and the exit code.
+-- The command is run in a subprocess.
+executeOut :: MonadIO m
+           => FilePath          -- ^ command as filename, e.g. 'ls'
+           -> [String]          -- ^ arguments to the command
+           -> Maybe FilePath    -- ^ chdir to this path
+           -> m CapturedProcess
+executeOut path args chdir = liftIO $ captureOutStreams $ do
+  maybe (pure ()) changeWorkingDirectory chdir
+  SPP.executeFile path True args Nothing
+
+
+execLogged :: ( MonadReader env m
+              , HasSettings env
+              , HasLog env
+              , HasDirs env
+              , MonadIO m
+              , MonadThrow m)
+           => FilePath         -- ^ thing to execute
+           -> [String]         -- ^ args for the thing
+           -> Maybe FilePath   -- ^ optionally chdir into this
+           -> FilePath         -- ^ log filename (opened in append mode)
+           -> Maybe [(String, String)] -- ^ optional environment
+           -> m (Either ProcessError ())
+execLogged exe args chdir lfile env = do
+  Settings {..} <- getSettings
+  Dirs {..} <- getDirs
+  logDebug $ T.pack $ "Running " <> exe <> " with arguments " <> show args
+  let logfile = fromGHCupPath logsDir </> lfile <> ".log"
+  liftIO $ bracket (openFd logfile WriteOnly (Just newFilePerms) defaultFileFlags{ append = True })
+                   closeFd
+                   (action verbose noColor)
+ where
+  action verbose no_color fd = do
+    actionWithPipes $ \(stdoutRead, stdoutWrite) -> do
+      -- start the thread that logs to stdout
+      pState <- newEmptyMVar
+      done   <- newEmptyMVar
+      void
+        $ forkIO
+        $ EX.handle (\(_ :: IOException) -> pure ())
+        $ EX.finally
+            (if verbose
+              then tee fd stdoutRead
+              else printToRegion fd stdoutRead 6 pState no_color
+            )
+            (putMVar done ())
+
+      -- fork the subprocess
+      pid <- SPP.forkProcess $ do
+        void $ dupTo stdoutWrite stdOutput
+        void $ dupTo stdoutWrite stdError
+        closeFd stdoutRead
+        closeFd stdoutWrite
+
+        -- execute the action
+        maybe (pure ()) changeWorkingDirectory chdir
+        void $ SPP.executeFile exe (not ("./" `isPrefixOf` exe)) args env
+
+      closeFd stdoutWrite
+
+      -- wait for the subprocess to finish
+      e <- toProcessError exe args <$!> SPP.getProcessStatus True True pid
+      putMVar pState (either (const False) (const True) e)
+
+      void $ race (takeMVar done) (threadDelay (1000000 * 3))
+      closeFd stdoutRead
+
+      pure e
+
+  tee :: Fd -> Fd -> IO ()
+  tee fileFd = readTilEOF lineAction
+
+   where
+    lineAction :: ByteString -> IO ()
+    lineAction bs' = do
+      void $ SPIB.fdWrite fileFd (bs' <> "\n")
+      void $ SPIB.fdWrite stdOutput (bs' <> "\n")
+
+  -- Reads fdIn and logs the output in a continous scrolling area
+  -- of 'size' terminal lines. Also writes to a log file.
+  printToRegion :: Fd -> Fd -> Int -> MVar Bool -> Bool -> IO ()
+  printToRegion fileFd fdIn size pState no_color = do
+    -- init region
+    forM_ [1..size] $ \_ -> BS.hPut stderr "\n"
+
+    void $ flip runStateT mempty
+      $ do
+        handle
+          (\(ex :: SomeException) -> do
+            ps <- liftIO $ takeMVar pState
+            when ps (liftIO $ BS.hPut stderr (pos1 <> moveLineUp size <> clearScreen))
+            throw ex
+          ) $ readTilEOF lineAction fdIn
+
+   where
+    clearScreen :: ByteString
+    clearScreen = "\x1b[0J"
+    clearLine :: ByteString
+    clearLine = "\x1b[2K"
+    moveLineUp :: Int -> ByteString
+    moveLineUp n = "\x1b[" <> E.encodeUtf8 (T.pack (show n)) <> "A"
+    moveLineDown :: Int -> ByteString
+    moveLineDown n = "\x1b[" <> E.encodeUtf8 (T.pack (show n)) <> "B"
+    pos1 :: ByteString
+    pos1 = "\r"
+    overwriteNthLine :: Int -> ByteString -> ByteString
+    overwriteNthLine n str = pos1 <> moveLineUp n <> clearLine <> str <> moveLineDown n <> pos1
+
+    blue :: ByteString -> ByteString
+    blue bs 
+      | no_color = bs
+      | otherwise = "\x1b[0;34m" <> bs <> "\x1b[0m"
+
+    -- action to perform line by line
+    lineAction :: (MonadMask m, MonadIO m)
+               => ByteString
+               -> StateT (Seq ByteString) m ()
+    lineAction = \bs' -> do
+      void $ liftIO $ SPIB.fdWrite fileFd (bs' <> "\n")
+      modify (swapRegs bs')
+      liftIO TP.size >>= \case
+        Nothing -> pure ()
+        Just (TP.Window _ w) -> do
+          regs <- get
+          liftIO $ forM_ (Sq.zip regs (Sq.fromList [0..(Sq.length regs - 1)])) $ \(bs, i) -> do
+              BS.hPut stderr
+              . overwriteNthLine (size - i)
+              . trim w
+              . blue
+              . (\b -> "[ " <> E.encodeUtf8 (T.pack lfile) <> " ] " <> b)
+              $ bs
+
+    swapRegs :: a -> Seq a -> Seq a
+    swapRegs bs = \regs -> if
+      | Sq.length regs < size -> regs |> bs
+      | otherwise             -> Sq.drop 1 regs |> bs
+
+    -- trim output line to terminal width
+    trim :: Int -> ByteString -> ByteString
+    trim w = \bs -> if
+      | BS.length bs > w && w > 5 -> BS.take (w - 4) bs <> "..."
+      | otherwise                 -> bs
+
+  -- Consecutively read from Fd in 512 chunks until we hit
+  -- newline or EOF.
+  readLine :: MonadIO m
+           => Fd          -- ^ input file descriptor
+           -> ByteString  -- ^ rest buffer (read across newline)
+           -> m (ByteString, ByteString, Bool) -- ^ (full line, rest, eof)
+  readLine fd = go
+   where
+    go inBs = do
+      -- if buffer is not empty, process it first
+      mbs <- if BS.length inBs == 0
+               -- otherwise attempt read
+               then liftIO
+                    $ handleIO (\e -> if isEOFError e then pure Nothing else ioError e)
+                    $ fmap Just
+                    $ SPIB.fdRead fd 512
+               else pure $ Just inBs
+      case mbs of
+        Nothing -> pure ("", "", True)
+        Just bs -> do
+          -- split on newline
+          let (line, rest) = BS.span (/= _lf) bs
+          if
+            | BS.length rest /= 0 -> pure (line, BS.tail rest, False)
+            -- if rest is empty, then there was no newline, process further
+            | otherwise           -> (\(l, r, b) -> (line <> l, r, b)) <$!> go mempty
+
+  readTilEOF :: MonadIO m => (ByteString -> m a) -> Fd -> m ()
+  readTilEOF ~action' fd' = go mempty
+   where
+    go bs' = do
+      (bs, rest, eof) <- readLine fd' bs'
+      if eof
+         then liftIO $ ioError (mkIOError eofErrorType "" Nothing Nothing)
+         else void (action' bs) >> go rest
+
+
+-- | Capture the stdout and stderr of the given action, which
+-- is run in a subprocess. Stdin is closed. You might want to
+-- 'race' this to make sure it terminates.
+captureOutStreams :: IO a
+                     -- ^ the action to execute in a subprocess
+                  -> IO CapturedProcess
+captureOutStreams action = do
+  actionWithPipes $ \(parentStdoutRead, childStdoutWrite) ->
+    actionWithPipes $ \(parentStderrRead, childStderrWrite) -> do
+      pid <- SPP.forkProcess $ do
+        -- dup stdout
+        void $ dupTo childStdoutWrite stdOutput
+        closeFd childStdoutWrite
+        closeFd parentStdoutRead
+
+        -- dup stderr
+        void $ dupTo childStderrWrite stdError
+        closeFd childStderrWrite
+        closeFd parentStderrRead
+
+        -- execute the action
+        a <- action
+        void $ E.evaluate a
+
+      -- close everything we don't need
+      closeFd childStdoutWrite
+      closeFd childStderrWrite
+
+      -- start thread that writes the output
+      refOut <- newIORef BL.empty
+      refErr <- newIORef BL.empty
+      done   <- newEmptyMVar
+      _      <-
+        forkIO
+        $ EX.handle (\(_ :: IOException) -> pure ())
+        $ flip EX.finally (putMVar done ())
+        $ writeStds parentStdoutRead parentStderrRead refOut refErr
+
+      status <- SPP.getProcessStatus True True pid
+      void $ race (takeMVar done) (threadDelay (1000000 * 3))
+
+      case status of
+        -- readFd will take care of closing the fd
+        Just (SPP.Exited es) -> do
+          stdout' <- readIORef refOut
+          stderr' <- readIORef refErr
+          pure $ CapturedProcess { _exitCode = es
+                                 , _stdOut   = stdout'
+                                 , _stdErr   = stderr'
+                                 }
+
+        _ -> throwIO $ userError ("No such PID " ++ show pid)
+
+ where
+  writeStds :: Fd -> Fd -> IORef BL.ByteString -> IORef BL.ByteString -> IO ()
+  writeStds pout perr rout rerr = do
+    doneOut <- newEmptyMVar
+    void
+      $ forkIO
+      $ hideError eofErrorType
+      $ flip EX.finally (putMVar doneOut ())
+      $ readTilEOF (\x -> modifyIORef' rout (<> BL.fromStrict x)) pout
+    doneErr <- newEmptyMVar
+    void
+      $ forkIO
+      $ hideError eofErrorType
+      $ flip EX.finally (putMVar doneErr ())
+      $ readTilEOF (\x -> modifyIORef' rerr (<> BL.fromStrict x)) perr
+    takeMVar doneOut
+    takeMVar doneErr
+
+  readTilEOF ~action' fd' = do
+    bs <- SPIB.fdRead fd' 512
+    void $ action' bs
+    readTilEOF action' fd'
+
+
+actionWithPipes :: ((Fd, Fd) -> IO b) -> IO b
+actionWithPipes a =
+  createPipe >>= \(p1, p2) -> flip finally (cleanup [p1, p2]) $ a (p1, p2)
+
+cleanup :: [Fd] -> IO ()
+cleanup fds = for_ fds $ \fd -> handleIO (\_ -> pure ()) $ closeFd fd
+
+
+
+-- | Create a new regular file in write-only mode. The file must not exist.
+createRegularFileFd :: FileMode -> FilePath -> IO Fd
+createRegularFileFd fm dest =
+  openFd dest WriteOnly (Just fm) defaultFileFlags{ exclusive = True }
+
+
+-- | Thin wrapper around `executeFile`.
+exec :: MonadIO m
+     => String           -- ^ thing to execute
+     -> [String]         -- ^ args for the thing
+     -> Maybe FilePath   -- ^ optionally chdir into this
+     -> Maybe [(String, String)] -- ^ optional environment
+     -> m (Either ProcessError ())
+exec exe args chdir env = liftIO $ do
+  pid <- SPP.forkProcess $ do
+    maybe (pure ()) changeWorkingDirectory chdir
+    SPP.executeFile exe (not ("./" `isPrefixOf` exe)) args env
+
+  fmap (toProcessError exe args) $ SPP.getProcessStatus True True pid
+
+
+toProcessError :: FilePath
+               -> [String]
+               -> Maybe ProcessStatus
+               -> Either ProcessError ()
+toProcessError exe args mps = case mps of
+  Just (SPP.Exited (ExitFailure xi)) -> Left $ NonZeroExit xi exe args
+  Just (SPP.Exited ExitSuccess    ) -> Right ()
+  Just (Terminated _ _             ) -> Left $ PTerminated exe args
+  Just (Stopped _                  ) -> Left $ PStopped exe args
+  Nothing                            -> Left $ NoSuchPid exe args
+
+
+
diff --git a/lib/GHCup/Prelude/Process/Windows.hs b/lib/GHCup/Prelude/Process/Windows.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Process/Windows.hs
@@ -0,0 +1,278 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleContexts  #-}
+{-# LANGUAGE DataKinds  #-}
+
+{-|
+Module      : GHCup.Utils.Process.Windows
+Description : Process handling for windows
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : Windows
+-}
+module GHCup.Prelude.Process.Windows where
+
+import           GHCup.Utils.Dirs
+import           GHCup.Prelude.File.Search
+import           GHCup.Prelude.Logger.Internal
+import           GHCup.Types
+import           GHCup.Types.Optics
+
+import           Control.Concurrent
+import           Control.DeepSeq
+import           Control.Exception.Safe
+import           Control.Monad
+import           Control.Monad.Reader
+import           Data.List
+import           Foreign.C.Error
+import           GHC.IO.Exception
+import           GHC.IO.Handle
+import           System.Environment
+import           System.FilePath
+import           System.IO
+import           System.Process
+
+import qualified Control.Exception             as EX
+import qualified Data.ByteString               as BS
+import qualified Data.ByteString.Lazy          as BL
+import qualified Data.Map.Strict               as Map
+import qualified Data.Text                     as T
+
+
+
+
+toProcessError :: FilePath
+               -> [FilePath]
+               -> ExitCode
+               -> Either ProcessError ()
+toProcessError exe args exitcode = case exitcode of
+  (ExitFailure xi) -> Left $ NonZeroExit xi exe args
+  ExitSuccess -> Right ()
+
+
+-- | @readCreateProcessWithExitCode@ works exactly like 'readProcessWithExitCode' except that it
+-- lets you pass 'CreateProcess' giving better flexibility.
+--
+-- Note that @Handle@s provided for @std_in@, @std_out@, or @std_err@ via the CreateProcess
+-- record will be ignored.
+--
+-- @since 1.2.3.0
+readCreateProcessWithExitCodeBS
+    :: CreateProcess
+    -> BL.ByteString
+    -> IO (ExitCode, BL.ByteString, BL.ByteString) -- ^ exitcode, stdout, stderr
+readCreateProcessWithExitCodeBS cp input = do
+    let cp_opts = cp {
+                    std_in  = CreatePipe,
+                    std_out = CreatePipe,
+                    std_err = CreatePipe
+                  }
+    withCreateProcess_ "readCreateProcessWithExitCodeBS" cp_opts $
+      \mb_inh mb_outh mb_errh ph ->
+        case (mb_inh, mb_outh, mb_errh) of
+          (Just inh, Just outh, Just errh) -> do
+
+            out <- BS.hGetContents outh
+            err <- BS.hGetContents errh
+
+            -- fork off threads to start consuming stdout & stderr
+            withForkWait  (EX.evaluate $ rnf out) $ \waitOut ->
+             withForkWait (EX.evaluate $ rnf err) $ \waitErr -> do
+
+              -- now write any input
+              unless (BL.null input) $
+                ignoreSigPipe $ BL.hPut inh input
+              -- hClose performs implicit hFlush, and thus may trigger a SIGPIPE
+              ignoreSigPipe $ hClose inh
+
+              -- wait on the output
+              waitOut
+              waitErr
+
+              hClose outh
+              hClose errh
+
+            -- wait on the process
+            ex <- waitForProcess ph
+            return (ex, BL.fromStrict out, BL.fromStrict err)
+
+          (Nothing,_,_) -> error "readCreateProcessWithExitCodeBS: Failed to get a stdin handle."
+          (_,Nothing,_) -> error "readCreateProcessWithExitCodeBS: Failed to get a stdout handle."
+          (_,_,Nothing) -> error "readCreateProcessWithExitCodeBS: Failed to get a stderr handle."
+ where
+  ignoreSigPipe :: IO () -> IO ()
+  ignoreSigPipe = EX.handle $ \e -> case e of
+                                     IOError { ioe_type  = ResourceVanished
+                                             , ioe_errno = Just ioe }
+                                       | Errno ioe == ePIPE -> return ()
+                                     _ -> throwIO e
+  -- wrapper so we can get exceptions with the appropriate function name.
+  withCreateProcess_
+    :: String
+    -> CreateProcess
+    -> (Maybe Handle -> Maybe Handle -> Maybe Handle -> ProcessHandle -> IO a)
+    -> IO a
+  withCreateProcess_ fun c action =
+      EX.bracketOnError (createProcess_ fun c) cleanupProcess
+                       (\(m_in, m_out, m_err, ph) -> action m_in m_out m_err ph)
+
+-- | Fork a thread while doing something else, but kill it if there's an
+-- exception.
+--
+-- This is important in the cases above because we want to kill the thread
+-- that is holding the Handle lock, because when we clean up the process we
+-- try to close that handle, which could otherwise deadlock.
+--
+withForkWait :: IO () -> (IO () ->  IO a) -> IO a
+withForkWait async' body = do
+  waitVar <- newEmptyMVar :: IO (MVar (Either SomeException ()))
+  mask $ \restore -> do
+    tid <- forkIO $ try (restore async') >>= putMVar waitVar
+    let wait' = takeMVar waitVar >>= either throwIO return
+    restore (body wait') `EX.onException` killThread tid
+
+
+-- | Execute the given command and collect the stdout, stderr and the exit code.
+-- The command is run in a subprocess.
+executeOut :: MonadIO m
+           => FilePath          -- ^ command as filename, e.g. 'ls'
+           -> [String]          -- ^ arguments to the command
+           -> Maybe FilePath    -- ^ chdir to this path
+           -> m CapturedProcess
+executeOut path args chdir = do
+  cp <- createProcessWithMingwPath ((proc path args){ cwd = chdir })
+  (exit, out, err) <- liftIO $ readCreateProcessWithExitCodeBS cp ""
+  pure $ CapturedProcess exit out err
+
+
+execLogged :: ( MonadReader env m
+              , HasDirs env
+              , HasLog env
+              , HasSettings env
+              , MonadIO m
+              , MonadThrow m)
+           => FilePath         -- ^ thing to execute
+           -> [String]         -- ^ args for the thing
+           -> Maybe FilePath   -- ^ optionally chdir into this
+           -> FilePath         -- ^ log filename (opened in append mode)
+           -> Maybe [(String, String)] -- ^ optional environment
+           -> m (Either ProcessError ())
+execLogged exe args chdir lfile env = do
+  Dirs {..} <- getDirs
+  logDebug $ T.pack $ "Running " <> exe <> " with arguments " <> show args
+  let stdoutLogfile = fromGHCupPath logsDir </> lfile <> ".stdout.log"
+      stderrLogfile = fromGHCupPath logsDir </> lfile <> ".stderr.log"
+  cp <- createProcessWithMingwPath ((proc exe args)
+    { cwd = chdir
+    , env = env
+    , std_in = CreatePipe
+    , std_out = CreatePipe
+    , std_err = CreatePipe
+    })
+  fmap (toProcessError exe args)
+    $ liftIO
+    $ withCreateProcess cp
+    $ \_ mout merr ph ->
+        case (mout, merr) of
+          (Just cStdout, Just cStderr) -> do
+            withForkWait (tee stdoutLogfile cStdout) $ \waitOut ->
+              withForkWait (tee stderrLogfile cStderr) $ \waitErr -> do
+                waitOut
+                waitErr
+            waitForProcess ph
+          _ -> fail "Could not acquire out/err handle"
+
+ where
+  tee :: FilePath -> Handle -> IO ()
+  tee logFile handle' = go
+    where
+      go = do
+        some <- BS.hGetSome handle' 512
+        if BS.null some
+          then pure ()
+          else do
+            void $ BS.appendFile logFile some
+            -- subprocess stdout also goes to stderr for logging
+            void $ BS.hPut stderr some
+            go
+
+
+-- | Thin wrapper around `executeFile`.
+exec :: MonadIO m
+     => FilePath       -- ^ thing to execute
+     -> [FilePath]     -- ^ args for the thing
+     -> Maybe FilePath   -- ^ optionally chdir into this
+     -> Maybe [(String, String)] -- ^ optional environment
+     -> m (Either ProcessError ())
+exec exe args chdir env = do
+  -- https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/375
+  forM_ (Map.fromList <$> env) $ \cEnv -> do
+    let paths = ["PATH", "Path"]
+        curPaths = (\x -> maybe [] splitSearchPath (Map.lookup x cEnv)) =<< paths
+        newPath = intercalate [searchPathSeparator] curPaths
+    liftIO $ setEnv "PATH" ""
+    liftIO $ setEnv "Path" newPath
+  cp <- createProcessWithMingwPath ((proc exe args) { cwd = chdir, env = env })
+  exit_code <- liftIO $ withCreateProcess cp $ \_ _ _ p -> waitForProcess p
+  pure $ toProcessError exe args exit_code
+
+-- | Like 'exec', except doesn't add msys2 stuff to PATH.
+execNoMinGW :: MonadIO m
+     => FilePath       -- ^ thing to execute
+     -> [FilePath]     -- ^ args for the thing
+     -> Maybe FilePath   -- ^ optionally chdir into this
+     -> Maybe [(String, String)] -- ^ optional environment
+     -> m (Either ProcessError ())
+execNoMinGW exe args chdir env = do
+  -- https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/375
+  forM_ (Map.fromList <$> env) $ \cEnv -> do
+    let paths = ["PATH", "Path"]
+        curPaths = (\x -> maybe [] splitSearchPath (Map.lookup x cEnv)) =<< paths
+        newPath = intercalate [searchPathSeparator] curPaths
+    liftIO $ setEnv "PATH" ""
+    liftIO $ setEnv "Path" newPath
+  let cp = (proc exe args) { cwd = chdir, env = env }
+  exit_code <- liftIO $ withCreateProcess cp $ \_ _ _ p -> waitForProcess p
+  pure $ toProcessError exe args exit_code
+
+
+-- | Thin wrapper around `executeFile`.
+execShell :: MonadIO m
+          => FilePath       -- ^ thing to execute
+          -> [FilePath]     -- ^ args for the thing
+          -> Maybe FilePath   -- ^ optionally chdir into this
+          -> Maybe [(String, String)] -- ^ optional environment
+          -> m (Either ProcessError ())
+execShell exe args chdir env = do
+  let cmd = exe <> " " <> concatMap (' ':) args
+  cp <- createProcessWithMingwPath ((shell cmd) { cwd = chdir, env = env })
+  exit_code <- liftIO $ withCreateProcess cp $ \_ _ _ p -> waitForProcess p
+  pure $ toProcessError cmd [] exit_code
+
+
+createProcessWithMingwPath :: MonadIO m
+                          => CreateProcess
+                          -> m CreateProcess
+createProcessWithMingwPath cp = do
+  msys2Dir <- liftIO ghcupMsys2Dir
+  cEnv <- Map.fromList <$> maybe (liftIO getEnvironment) pure (env cp)
+  let mingWPaths = [msys2Dir </> "mingw64" </> "bin"
+                   ,msys2Dir </> "usr" </> "bin"
+                   ]
+      paths = ["PATH", "Path"]
+      curPaths = (\x -> maybe [] splitSearchPath (Map.lookup x cEnv)) =<< paths
+      newPath = intercalate [searchPathSeparator] (mingWPaths ++ curPaths)
+      envWithoutPath = foldr (\x y -> Map.delete x y) cEnv paths
+      envWithNewPath = Map.insert "Path" newPath envWithoutPath
+  liftIO $ setEnv "Path" newPath
+  pure $ cp { env = Just $ Map.toList envWithNewPath }
+
+ghcupMsys2Dir :: IO FilePath
+ghcupMsys2Dir =
+  lookupEnv "GHCUP_MSYS2" >>= \case
+    Just fp -> pure fp
+    Nothing -> do
+      baseDir <- liftIO ghcupBaseDir
+      pure (fromGHCupPath baseDir </> "msys64")
+
diff --git a/lib/GHCup/Prelude/String/QQ.hs b/lib/GHCup/Prelude/String/QQ.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/String/QQ.hs
@@ -0,0 +1,57 @@
+{-# LANGUAGE TemplateHaskellQuotes #-}
+
+{-|
+Module      : GHCup.Utils.String.QQ
+Description : String quasi quoters
+Copyright   : (c) Audrey Tang <audreyt@audreyt.org> 2019, Julian Ospald <hasufell@posteo.de> 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+
+QuasiQuoter for non-interpolated strings, texts and bytestrings.
+
+The "s" quoter contains a multi-line string with no interpolation at all,
+except that the leading newline is trimmed and carriage returns stripped.
+
+@
+{-\# LANGUAGE QuasiQuotes #-}
+import Data.Text (Text)
+import Data.String.QQ
+foo :: Text -- "String", "ByteString" etc also works
+foo = [s|
+Well here is a
+    multi-line string!
+|]
+@
+
+Any instance of the IsString type is permitted.
+
+(For GHC versions 6, write "[$s||]" instead of "[s||]".)
+
+-}
+module GHCup.Prelude.String.QQ
+  ( s
+  )
+where
+
+
+import           Data.Char
+import           GHC.Exts                       ( IsString(..) )
+import           Language.Haskell.TH.Quote
+
+-- | QuasiQuoter for a non-interpolating ASCII IsString literal.
+-- The pattern portion is undefined.
+s :: QuasiQuoter
+s = QuasiQuoter
+  (\s' -> case all isAscii s' of
+    True  -> (\a -> [|fromString a|]) . trimLeadingNewline . removeCRs $ s'
+    False -> fail "Not ascii"
+  )
+  (error "Cannot use s as a pattern")
+  (error "Cannot use s as a type")
+  (error "Cannot use s as a dec")
+ where
+  removeCRs = filter (/= '\r')
+  trimLeadingNewline ('\n' : xs) = xs
+  trimLeadingNewline xs          = xs
diff --git a/lib/GHCup/Prelude/Version/QQ.hs b/lib/GHCup/Prelude/Version/QQ.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Version/QQ.hs
@@ -0,0 +1,107 @@
+{-# OPTIONS_GHC -Wno-orphans    #-}
+{-# LANGUAGE CPP                #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE DeriveLift         #-}
+{-# LANGUAGE FlexibleInstances  #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE TemplateHaskellQuotes #-}
+
+
+{-|
+Module      : GHCup.Utils.Version.QQ
+Description : Version quasi-quoters
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+-}
+module GHCup.Prelude.Version.QQ where
+
+import           Data.Data
+import           Data.Text                      ( Text )
+import           Data.Versions
+#if !MIN_VERSION_base(4,13,0)
+import           GHC.Base
+#endif
+import           Language.Haskell.TH
+import           Language.Haskell.TH.Quote      ( QuasiQuoter(..) )
+import           Language.Haskell.TH.Syntax     ( Lift
+                                                , dataToExpQ
+                                                )
+import qualified Data.Text                     as T
+import qualified Language.Haskell.TH.Syntax    as TH
+
+
+
+deriving instance Data Versioning
+deriving instance Lift Versioning
+deriving instance Data Version
+deriving instance Lift Version
+deriving instance Data SemVer
+deriving instance Lift SemVer
+deriving instance Data Mess
+deriving instance Lift Mess
+deriving instance Data MChunk
+deriving instance Lift MChunk
+deriving instance Data PVP
+deriving instance Lift PVP
+deriving instance Lift VSep
+deriving instance Data VSep
+deriving instance Lift VUnit
+deriving instance Data VUnit
+
+#if !MIN_VERSION_base(4,13,0)
+deriving instance Lift (NonEmpty Word)
+deriving instance Lift (NonEmpty VChunk)
+deriving instance Lift (NonEmpty MChunk)
+deriving instance Lift (NonEmpty VUnit)
+#endif
+
+qq :: (Text -> Q Exp) -> QuasiQuoter
+qq quoteExp' = QuasiQuoter
+  { quoteExp  = \s -> quoteExp' . T.pack $ s
+  , quotePat  = \_ ->
+    fail "illegal QuasiQuote (allowed as expression only, used as a pattern)"
+  , quoteType = \_ ->
+    fail "illegal QuasiQuote (allowed as expression only, used as a type)"
+  , quoteDec  = \_ -> fail
+    "illegal QuasiQuote (allowed as expression only, used as a declaration)"
+  }
+
+vver :: QuasiQuoter
+vver = qq mkV
+ where
+  mkV :: Text -> Q Exp
+  mkV = either (fail . show) liftDataWithText . version
+
+mver :: QuasiQuoter
+mver = qq mkV
+ where
+  mkV :: Text -> Q Exp
+  mkV = either (fail . show) liftDataWithText . mess
+
+sver :: QuasiQuoter
+sver = qq mkV
+ where
+  mkV :: Text -> Q Exp
+  mkV = either (fail . show) liftDataWithText . semver
+
+vers :: QuasiQuoter
+vers = qq mkV
+ where
+  mkV :: Text -> Q Exp
+  mkV = either (fail . show) liftDataWithText . versioning
+
+pver :: QuasiQuoter
+pver = qq mkV
+ where
+  mkV :: Text -> Q Exp
+  mkV = either (fail . show) liftDataWithText . pvp
+
+-- https://stackoverflow.com/questions/38143464/cant-find-inerface-file-declaration-for-variable
+liftText :: T.Text -> Q Exp
+liftText txt = AppE (VarE 'T.pack) <$> TH.lift (T.unpack txt)
+
+liftDataWithText :: Data a => a -> Q Exp
+liftDataWithText = dataToExpQ (fmap liftText . cast)
diff --git a/lib/GHCup/Prelude/Windows.hs b/lib/GHCup/Prelude/Windows.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prelude/Windows.hs
@@ -0,0 +1,53 @@
+{-# LANGUAGE CPP                   #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE OverloadedStrings     #-}
+
+module GHCup.Prelude.Windows where
+
+
+import           Control.Exception.Safe
+import           Control.Monad
+#if !MIN_VERSION_base(4,13,0)
+import           Control.Monad.Fail             ( MonadFail )
+#endif
+import           Data.Bits
+
+import           System.Win32.Console
+import           System.Win32.File     hiding ( copyFile )
+import           System.Win32.Types
+
+
+
+
+-- | Enables ANSI support on windows, does nothing on unix.
+--
+-- Returns 'Left str' on errors and 'Right bool' on success, where
+-- 'bool' markes whether ansi support was already enabled.
+--
+-- This function never crashes.
+--
+-- Rip-off of https://docs.rs/ansi_term/0.12.1/x86_64-pc-windows-msvc/src/ansi_term/windows.rs.html#10-61
+enableAnsiSupport :: IO (Either String Bool)
+enableAnsiSupport = handleIO (pure . Left . displayException) $ do
+  -- ref: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
+  -- Using `CreateFileW("CONOUT$", ...)` to retrieve the console handle works correctly even if STDOUT and/or STDERR are redirected
+  h <- createFile "CONOUT$" (gENERIC_WRITE .|. gENERIC_READ)
+    fILE_SHARE_WRITE Nothing oPEN_EXISTING 0 Nothing
+  when (h == iNVALID_HANDLE_VALUE ) $ fail "invalid handle value"
+
+  -- ref: https://docs.microsoft.com/en-us/windows/console/getconsolemode
+  m <- getConsoleMode h
+
+  -- VT processing not already enabled?
+  if m .&. eNABLE_VIRTUAL_TERMINAL_PROCESSING == 0
+  -- https://docs.microsoft.com/en-us/windows/console/setconsolemode
+  then setConsoleMode h (m .|. eNABLE_VIRTUAL_TERMINAL_PROCESSING)
+    >> pure (Right False)
+  else pure (Right True)
+
+
+isWindows, isNotWindows :: Bool
+isWindows = True
+isNotWindows = not isWindows
+
diff --git a/lib/GHCup/Prompts.hs b/lib/GHCup/Prompts.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Prompts.hs
@@ -0,0 +1,28 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleContexts #-}
+
+module GHCup.Prompts
+  ( PromptQuestion,
+    PromptResponse (..),
+    getUserPromptResponse,
+  )
+where
+
+import Control.Monad.Reader
+import qualified Data.Text.IO as TIO
+import GHCup.Prelude.Logger
+import GHCup.Types.Optics
+import GHCup.Types (PromptQuestion, PromptResponse(..))
+
+getUserPromptResponse :: ( HasLog env
+                         , MonadReader env m
+                         , MonadIO m)
+                      => PromptQuestion
+                      -> m PromptResponse
+
+getUserPromptResponse prompt = do
+  logInfo prompt
+  resp <- liftIO TIO.getLine
+  if resp `elem` ["YES", "yes", "y", "Y"]
+    then pure PromptYes
+    else pure PromptNo
diff --git a/lib/GHCup/Stack.hs b/lib/GHCup/Stack.hs
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Stack.hs
@@ -0,0 +1,283 @@
+{-# LANGUAGE CPP                   #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings     #-}
+
+{-|
+Module      : GHCup.Stack
+Description : GHCup installation functions for Stack
+Copyright   : (c) Julian Ospald, 2020
+License     : LGPL-3.0
+Maintainer  : hasufell@hasufell.de
+Stability   : experimental
+Portability : portable
+-}
+module GHCup.Stack where
+
+import           GHCup.Download
+import           GHCup.Errors
+import           GHCup.Types
+import           GHCup.Types.JSON               ( )
+import           GHCup.Types.Optics
+import           GHCup.Utils
+import           GHCup.Prelude
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger
+
+import           Codec.Archive                  ( ArchiveResult )
+import           Control.Applicative
+import           Control.Exception.Safe
+import           Control.Monad
+#if !MIN_VERSION_base(4,13,0)
+import           Control.Monad.Fail             ( MonadFail )
+#endif
+import           Control.Monad.Reader
+import           Control.Monad.Trans.Resource
+                                         hiding ( throwM )
+import           Data.Either
+import           Data.List
+import           Data.Maybe
+import           Data.Versions                hiding ( patch )
+import           Haskus.Utils.Variant.Excepts
+import           Optics
+import           Prelude                 hiding ( abs
+                                                , writeFile
+                                                )
+import           Safe                    hiding ( at )
+import           System.FilePath
+import           System.IO.Error
+
+import qualified Data.Text                     as T
+import Text.PrettyPrint.HughesPJClass (prettyShow)
+
+
+
+    --------------------
+    --[ Installation ]--
+    --------------------
+
+
+-- | Installs stack into @~\/.ghcup\/bin/stack-\<ver\>@ and
+-- creates a default @stack -> stack-x.y.z.q@ symlink for
+-- the latest installed version.
+installStackBin :: ( MonadMask m
+                   , MonadCatch m
+                   , MonadReader env m
+                   , HasDirs env
+                   , HasSettings env
+                   , HasPlatformReq env
+                   , HasGHCupInfo env
+                   , HasLog env
+                   , MonadResource m
+                   , MonadIO m
+                   , MonadUnliftIO m
+                   , MonadFail m
+                   )
+                => Version
+                -> InstallDir
+                -> Bool            -- ^ Force install
+                -> Excepts
+                     '[ AlreadyInstalled
+                      , CopyError
+                      , DigestError
+                      , GPGError
+                      , DownloadFailed
+                      , NoDownload
+                      , NotInstalled
+                      , UnknownArchive
+                      , TarDirDoesNotExist
+                      , ArchiveResult
+                      , FileAlreadyExistsError
+                      ]
+                     m
+                     ()
+installStackBin ver installDir forceInstall = do
+  dlinfo <- liftE $ getDownloadInfo Stack ver
+  installStackBindist dlinfo ver installDir forceInstall
+
+
+-- | Like 'installStackBin', except takes the 'DownloadInfo' as
+-- argument instead of looking it up from 'GHCupDownloads'.
+installStackBindist :: ( MonadMask m
+                       , MonadCatch m
+                       , MonadReader env m
+                       , HasPlatformReq env
+                       , HasDirs env
+                       , HasSettings env
+                       , HasLog env
+                       , MonadResource m
+                       , MonadIO m
+                       , MonadUnliftIO m
+                       , MonadFail m
+                       )
+                    => DownloadInfo
+                    -> Version
+                    -> InstallDir
+                    -> Bool           -- ^ Force install
+                    -> Excepts
+                         '[ AlreadyInstalled
+                          , CopyError
+                          , DigestError
+                          , GPGError
+                          , DownloadFailed
+                          , NoDownload
+                          , NotInstalled
+                          , UnknownArchive
+                          , TarDirDoesNotExist
+                          , ArchiveResult
+                          , FileAlreadyExistsError
+                          ]
+                         m
+                         ()
+installStackBindist dlinfo ver installDir forceInstall = do
+  lift $ logDebug $ "Requested to install stack version " <> prettyVer ver
+
+  PlatformRequest {..} <- lift getPlatformReq
+  Dirs {..} <- lift getDirs
+
+  regularStackInstalled <- lift $ stackInstalled ver
+
+  if
+    | not forceInstall
+    , regularStackInstalled
+    , GHCupInternal <- installDir -> do
+        throwE $ AlreadyInstalled Stack ver
+
+    | forceInstall
+    , regularStackInstalled
+    , GHCupInternal <- installDir -> do
+        lift $ logInfo "Removing the currently installed version of Stack first!"
+        liftE $ rmStackVer ver
+
+    | otherwise -> pure ()
+
+  -- download (or use cached version)
+  dl <- liftE $ downloadCached dlinfo Nothing
+
+  -- unpack
+  tmpUnpack <- lift withGHCupTmpDir
+  liftE $ cleanUpOnError tmpUnpack (unpackToDir (fromGHCupPath tmpUnpack) dl)
+  liftE $ catchWarn $ lEM @_ @'[ProcessError] $ darwinNotarization _rPlatform (fromGHCupPath tmpUnpack)
+
+  -- the subdir of the archive where we do the work
+  workdir <- maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
+
+  case installDir of
+    IsolateDir isoDir -> do                 -- isolated install
+      lift $ logInfo $ "isolated installing Stack to " <> T.pack isoDir
+      liftE $ installStackUnpacked workdir (IsolateDirResolved isoDir) ver forceInstall
+    GHCupInternal -> do                     -- regular install
+      liftE $ installStackUnpacked workdir (GHCupBinDir binDir) ver forceInstall
+
+
+-- | Install an unpacked stack distribution.
+installStackUnpacked :: (MonadReader env m, HasLog env, MonadCatch m, MonadIO m)
+              => GHCupPath      -- ^ Path to the unpacked stack bindist (where the executable resides)
+              -> InstallDirResolved
+              -> Version
+              -> Bool          -- ^ Force install
+              -> Excepts '[CopyError, FileAlreadyExistsError] m ()
+installStackUnpacked path installDir ver forceInstall = do
+  lift $ logInfo "Installing stack"
+  let stackFile = "stack"
+  liftIO $ createDirRecursive' (fromInstallDir installDir)
+  let destFileName = stackFile
+                     <> (case installDir of
+                          IsolateDirResolved _ -> ""
+                          _ -> ("-" <>) .  T.unpack . prettyVer $ ver
+                        )
+                     <> exeExt
+      destPath = fromInstallDir installDir </> destFileName
+
+  copyFileE
+    (fromGHCupPath path </> stackFile <> exeExt)
+    destPath
+    (not forceInstall)
+  lift $ chmod_755 destPath
+
+
+
+    -----------------
+    --[ Set stack ]--
+    -----------------
+
+
+-- | Set the @~\/.ghcup\/bin\/stack@ symlink.
+setStack :: ( MonadMask m
+            , MonadReader env m
+            , HasDirs env
+            , HasLog env
+            , MonadThrow m
+            , MonadFail m
+            , MonadIO m
+            , MonadUnliftIO m
+            )
+         => Version
+         -> Excepts '[NotInstalled] m ()
+setStack ver = do
+  let targetFile = "stack-" <> T.unpack (prettyVer ver) <> exeExt
+
+  -- symlink destination
+  Dirs {..} <- lift getDirs
+
+  whenM (liftIO $ not <$> doesFileExist (binDir </> targetFile))
+    $ throwE
+    $ NotInstalled Stack (GHCTargetVersion Nothing ver)
+
+  let stackbin = binDir </> "stack" <> exeExt
+
+  lift $ createLink targetFile stackbin
+
+  liftIO (isShadowed stackbin) >>= \case
+    Nothing -> pure ()
+    Just pa -> lift $ logWarn $ T.pack $ prettyShow (ToolShadowed Cabal pa stackbin ver)
+
+  pure ()
+
+
+unsetStack :: ( MonadMask m
+              , MonadReader env m
+              , HasDirs env
+              , MonadIO m)
+           => m ()
+unsetStack = do
+  Dirs {..} <- getDirs
+  let stackbin = binDir </> "stack" <> exeExt
+  hideError doesNotExistErrorType $ rmLink stackbin
+
+
+    ----------------
+    --[ Rm stack ]--
+    ----------------
+
+-- | Delete a stack version. Will try to fix the @stack@ symlink
+-- after removal (e.g. setting it to an older version).
+rmStackVer :: ( MonadMask m
+              , MonadReader env m
+              , HasDirs env
+              , MonadThrow m
+              , HasLog env
+              , MonadIO m
+              , MonadFail m
+              , MonadCatch m
+              , MonadUnliftIO m
+              )
+           => Version
+           -> Excepts '[NotInstalled] m ()
+rmStackVer ver = do
+  whenM (lift $ fmap not $ stackInstalled ver) $ throwE (NotInstalled Stack (GHCTargetVersion Nothing ver))
+
+  sSet      <- lift stackSet
+
+  Dirs {..} <- lift getDirs
+
+  let stackFile = "stack-" <> T.unpack (prettyVer ver) <> exeExt
+  lift $ hideError doesNotExistErrorType $ recycleFile (binDir </> stackFile)
+
+  when (Just ver == sSet) $ do
+    sVers <- lift $ fmap rights getInstalledStacks
+    case headMay . reverse . sort $ sVers of
+      Just latestver -> setStack latestver
+      Nothing        -> lift $ rmLink (binDir </> "stack" <> exeExt)
diff --git a/lib/GHCup/Types.hs b/lib/GHCup/Types.hs
--- a/lib/GHCup/Types.hs
+++ b/lib/GHCup/Types.hs
@@ -26,6 +26,8 @@
   )
   where
 
+import {-# SOURCE #-} GHCup.Utils.Dirs          ( fromGHCupPath, GHCupPath )
+
 import           Control.DeepSeq                ( NFData, rnf )
 import           Data.Map.Strict                ( Map )
 import           Data.List.NonEmpty             ( NonEmpty (..) )
@@ -405,6 +407,9 @@
 
 instance NFData AppState
 
+fromAppState :: AppState -> LeanAppState
+fromAppState AppState {..} = LeanAppState {..}
+
 data LeanAppState = LeanAppState
   { settings :: Settings
   , dirs :: Dirs
@@ -438,12 +443,14 @@
 instance NFData Settings
 
 data Dirs = Dirs
-  { baseDir  :: FilePath
-  , binDir   :: FilePath
-  , cacheDir :: FilePath
-  , logsDir  :: FilePath
-  , confDir  :: FilePath
-  , recycleDir :: FilePath -- mainly used on windows
+  { baseDir    :: GHCupPath
+  , binDir     :: FilePath
+  , cacheDir   :: GHCupPath
+  , logsDir    :: GHCupPath
+  , confDir    :: GHCupPath
+  , dbDir      :: GHCupPath
+  , recycleDir :: GHCupPath -- mainly used on windows
+  , tmpDir     :: GHCupPath
   }
   deriving (Show, GHC.Generic)
 
@@ -635,9 +642,22 @@
   deriving (Eq, Show)
 
 data InstallDirResolved = IsolateDirResolved FilePath
-                        | GHCupDir FilePath
+                        | GHCupDir GHCupPath
+                        | GHCupBinDir FilePath
   deriving (Eq, Show)
 
 fromInstallDir :: InstallDirResolved -> FilePath
 fromInstallDir (IsolateDirResolved fp) = fp
-fromInstallDir (GHCupDir fp) = fp
+fromInstallDir (GHCupDir fp) = fromGHCupPath fp
+fromInstallDir (GHCupBinDir fp) = fp
+
+
+isSafeDir :: InstallDirResolved -> Bool
+isSafeDir (IsolateDirResolved _) = False
+isSafeDir (GHCupDir _)           = True
+isSafeDir (GHCupBinDir _)        = False
+
+type PromptQuestion = Text
+
+data PromptResponse = PromptYes | PromptNo
+  deriving (Show, Eq)
diff --git a/lib/GHCup/Types/JSON.hs b/lib/GHCup/Types/JSON.hs
--- a/lib/GHCup/Types/JSON.hs
+++ b/lib/GHCup/Types/JSON.hs
@@ -23,7 +23,7 @@
 
 import           GHCup.Types
 import           GHCup.Types.JSON.Utils
-import           GHCup.Utils.MegaParsec
+import           GHCup.Prelude.MegaParsec
 
 import           Control.Applicative            ( (<|>) )
 import           Data.Aeson              hiding (Key)
@@ -79,37 +79,6 @@
 instance ToJSON URI where
   toJSON = toJSON . E.decodeUtf8With E.lenientDecode . serializeURIRef'
 
-instance FromJSON URLSource where
-  parseJSON v =
-        parseGHCupURL v
-    <|> parseOwnSourceLegacy v
-    <|> parseOwnSourceNew1 v
-    <|> parseOwnSourceNew2 v
-    <|> parseOwnSpec v
-    <|> legacyParseAddSource v
-    <|> newParseAddSource v
-   where
-    parseOwnSourceLegacy = withObject "URLSource" $ \o -> do
-      r :: URI <- o .: "OwnSource"
-      pure (OwnSource [Right r])
-    parseOwnSourceNew1 = withObject "URLSource" $ \o -> do
-      r :: [URI] <- o .: "OwnSource"
-      pure (OwnSource (fmap Right r))
-    parseOwnSourceNew2 = withObject "URLSource" $ \o -> do
-      r :: [Either GHCupInfo URI] <- o .: "OwnSource"
-      pure (OwnSource r)
-    parseOwnSpec = withObject "URLSource" $ \o -> do
-      r :: GHCupInfo <- o .: "OwnSpec"
-      pure (OwnSpec r)
-    parseGHCupURL = withObject "URLSource" $ \o -> do
-      _ :: [Value] <- o .: "GHCupURL"
-      pure GHCupURL
-    legacyParseAddSource = withObject "URLSource" $ \o -> do
-      r :: Either GHCupInfo URI <- o .: "AddSource"
-      pure (AddSource [r])
-    newParseAddSource = withObject "URLSource" $ \o -> do
-      r :: [Either GHCupInfo URI] <- o .: "AddSource"
-      pure (AddSource r)
 
 instance FromJSON URI where
   parseJSON = withText "URL" $ \t ->
@@ -349,7 +318,40 @@
 deriveToJSON defaultOptions { sumEncoding = ObjectWithSingleField } ''URLSource
 deriveJSON defaultOptions { sumEncoding = ObjectWithSingleField } ''Key
 deriveJSON defaultOptions { fieldLabelModifier = \str' -> maybe str' T.unpack . T.stripPrefix (T.pack "k-") . T.pack . kebab $ str' } ''UserKeyBindings
-deriveJSON defaultOptions { fieldLabelModifier = \str' -> maybe str' T.unpack . T.stripPrefix (T.pack "u-") . T.pack . kebab $ str' } ''UserSettings
-
 deriveToJSON defaultOptions { fieldLabelModifier = kebab } ''Settings
 deriveToJSON defaultOptions { fieldLabelModifier = drop 2 . kebab } ''KeyBindings -- move under key-bindings key
+
+instance FromJSON URLSource where
+  parseJSON v =
+        parseGHCupURL v
+    <|> parseOwnSourceLegacy v
+    <|> parseOwnSourceNew1 v
+    <|> parseOwnSourceNew2 v
+    <|> parseOwnSpec v
+    <|> legacyParseAddSource v
+    <|> newParseAddSource v
+   where
+    parseOwnSourceLegacy = withObject "URLSource" $ \o -> do
+      r :: URI <- o .: "OwnSource"
+      pure (OwnSource [Right r])
+    parseOwnSourceNew1 = withObject "URLSource" $ \o -> do
+      r :: [URI] <- o .: "OwnSource"
+      pure (OwnSource (fmap Right r))
+    parseOwnSourceNew2 = withObject "URLSource" $ \o -> do
+      r :: [Either GHCupInfo URI] <- o .: "OwnSource"
+      pure (OwnSource r)
+    parseOwnSpec = withObject "URLSource" $ \o -> do
+      r :: GHCupInfo <- o .: "OwnSpec"
+      pure (OwnSpec r)
+    parseGHCupURL = withObject "URLSource" $ \o -> do
+      _ :: [Value] <- o .: "GHCupURL"
+      pure GHCupURL
+    legacyParseAddSource = withObject "URLSource" $ \o -> do
+      r :: Either GHCupInfo URI <- o .: "AddSource"
+      pure (AddSource [r])
+    newParseAddSource = withObject "URLSource" $ \o -> do
+      r :: [Either GHCupInfo URI] <- o .: "AddSource"
+      pure (AddSource r)
+
+deriveJSON defaultOptions { fieldLabelModifier = \str' -> maybe str' T.unpack . T.stripPrefix (T.pack "u-") . T.pack . kebab $ str' } ''UserSettings
+
diff --git a/lib/GHCup/Utils.hs b/lib/GHCup/Utils.hs
--- a/lib/GHCup/Utils.hs
+++ b/lib/GHCup/Utils.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP                   #-}
+{-# LANGUAGE BangPatterns          #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE FlexibleContexts      #-}
 {-# LANGUAGE OverloadedStrings     #-}
@@ -22,18 +23,18 @@
   ( module GHCup.Utils.Dirs
   , module GHCup.Utils
 #if defined(IS_WINDOWS)
-  , module GHCup.Utils.Windows
+  , module GHCup.Prelude.Windows
 #else
-  , module GHCup.Utils.Posix
+  , module GHCup.Prelude.Posix
 #endif
   )
 where
 
 
 #if defined(IS_WINDOWS)
-import GHCup.Utils.Windows
+import GHCup.Prelude.Windows
 #else
-import GHCup.Utils.Posix
+import GHCup.Prelude.Posix
 #endif
 import           GHCup.Download
 import           GHCup.Errors
@@ -41,11 +42,13 @@
 import           GHCup.Types.Optics
 import           GHCup.Types.JSON               ( )
 import           GHCup.Utils.Dirs
-import           GHCup.Utils.File
-import           GHCup.Utils.Logger
-import           GHCup.Utils.MegaParsec
-import           GHCup.Utils.Prelude
-import           GHCup.Utils.String.QQ
+import           GHCup.Version
+import           GHCup.Prelude
+import           GHCup.Prelude.File
+import           GHCup.Prelude.Logger.Internal
+import           GHCup.Prelude.MegaParsec
+import           GHCup.Prelude.Process
+import           GHCup.Prelude.String.QQ
 
 import           Codec.Archive           hiding ( Directory )
 import           Control.Applicative
@@ -58,6 +61,7 @@
 import           Control.Monad.Trans.Resource
                                          hiding ( throwM )
 import           Control.Monad.IO.Unlift        ( MonadUnliftIO( withRunInIO ) )
+import           Data.Char                      ( isHexDigit )
 import           Data.Bifunctor                 ( first )
 import           Data.ByteString                ( ByteString )
 import           Data.Either
@@ -71,10 +75,10 @@
 import           Haskus.Utils.Variant.Excepts
 import           Optics
 import           Safe
-import           System.Directory      hiding   ( findFiles )
 import           System.FilePath
 import           System.IO.Error
 import           Text.Regex.Posix
+import           Text.PrettyPrint.HughesPJClass (prettyShow)
 import           URI.ByteString
 
 import qualified Codec.Compression.BZip        as BZip
@@ -86,6 +90,9 @@
 import qualified Data.Text.Encoding            as E
 import qualified Text.Megaparsec               as MP
 import qualified Data.List.NonEmpty            as NE
+import qualified Streamly.Prelude              as S
+import Control.DeepSeq (force)
+import GHC.IO (evaluate)
 
 
 -- $setup
@@ -96,14 +103,14 @@
 -- >>> import System.Directory
 -- >>> import URI.ByteString
 -- >>> import qualified Data.Text as T
--- >>> import GHCup.Utils.Prelude
+-- >>> import GHCup.Prelude
 -- >>> import GHCup.Download
 -- >>> import GHCup.Version
 -- >>> import GHCup.Errors
 -- >>> import GHCup.Types
 -- >>> import GHCup.Types.Optics
 -- >>> import Optics
--- >>> import GHCup.Utils.Version.QQ
+-- >>> import GHCup.Prelude.Version.QQ
 -- >>> import qualified Data.Text.Encoding as E
 -- >>> import Control.Monad.Reader
 -- >>> import Haskus.Utils.Variant.Excepts
@@ -277,14 +284,14 @@
 ghcInstalled :: (MonadIO m, MonadReader env m, HasDirs env, MonadThrow m) => GHCTargetVersion -> m Bool
 ghcInstalled ver = do
   ghcdir <- ghcupGHCDir ver
-  liftIO $ doesDirectoryExist ghcdir
+  liftIO $ doesDirectoryExist (fromGHCupPath ghcdir)
 
 
 -- | Whether the given GHC version is installed from source.
 ghcSrcInstalled :: (MonadIO m, MonadReader env m, HasDirs env, MonadThrow m) => GHCTargetVersion -> m Bool
 ghcSrcInstalled ver = do
   ghcdir <- ghcupGHCDir ver
-  liftIO $ doesFileExist (ghcdir </> ghcUpSrcBuiltFile)
+  liftIO $ doesFileExist (fromGHCupPath ghcdir </> ghcUpSrcBuiltFile)
 
 
 -- | Whether the given GHC version is set as the current.
@@ -327,7 +334,7 @@
 getInstalledGHCs :: (MonadReader env m, HasDirs env, MonadIO m) => m [Either FilePath GHCTargetVersion]
 getInstalledGHCs = do
   ghcdir <- ghcupGHCBaseDir
-  fs     <- liftIO $ hideErrorDef [NoSuchThing] [] $ listDirectory ghcdir
+  fs     <- liftIO $ hideErrorDef [NoSuchThing] [] $ listDirectory (fromGHCupPath ghcdir)
   forM fs $ \f -> case parseGHCupGHCDir f of
     Right r -> pure $ Right r
     Left  _ -> pure $ Left f
@@ -430,7 +437,7 @@
         Nothing        -> pure $ Left f
 
   hlsdir <- ghcupHLSBaseDir
-  fs     <- liftIO $ hideErrorDef [NoSuchThing] [] $ listDirectory hlsdir
+  fs     <- liftIO $ hideErrorDef [NoSuchThing] [] $ listDirectory (fromGHCupPath hlsdir)
   new <- forM fs $ \f -> case parseGHCupHLSDir f of
     Right r -> pure $ Right r
     Left  _ -> pure $ Left f
@@ -515,7 +522,7 @@
 isLegacyHLS :: (MonadIO m, MonadReader env m, HasDirs env, MonadCatch m) => Version -> m Bool
 isLegacyHLS ver = do
   bdir <- ghcupHLSDir ver
-  not <$> liftIO (doesDirectoryExist bdir)
+  not <$> liftIO (doesDirectoryExist $ fromGHCupPath bdir)
 
 
 -- Return the currently set hls version, if any.
@@ -616,7 +623,7 @@
                           -> m [FilePath]
 hlsInternalServerScripts ver mghcVer = do
   dir <- ghcupHLSDir ver
-  let bdir = dir </> "bin"
+  let bdir = fromGHCupPath dir </> "bin"
   fmap (bdir </>) . filter (\f -> maybe True (\gv -> ("-" <> T.unpack (prettyVer gv)) `isSuffixOf` f) mghcVer)
     <$> liftIO (listDirectory bdir)
 
@@ -627,7 +634,7 @@
                           -> Maybe Version   -- ^ optional GHC version
                           -> m [FilePath]
 hlsInternalServerBinaries ver mghcVer = do
-  dir <- ghcupHLSDir ver
+  dir <- fromGHCupPath <$> ghcupHLSDir ver
   let regex = makeRegexOpts compExtended execBlank ([s|^haskell-language-server-.*$|] :: ByteString)
   (Just bdir) <- fmap headMay $ liftIO $ expandFilePath [Left (dir </> "lib"), Right regex, Left "bin"]
   fmap (bdir </>) . filter (\f -> maybe True (\gv -> ("-" <> T.unpack (prettyVer gv)) `isSuffixOf` f) mghcVer)
@@ -641,7 +648,7 @@
                       -> Version   -- ^ GHC version
                       -> m [FilePath]
 hlsInternalServerLibs ver ghcVer = do
-  dir <- ghcupHLSDir ver
+  dir <- fromGHCupPath <$> ghcupHLSDir ver
   let regex = makeRegexOpts compExtended execBlank ([s|^haskell-language-server-.*$|] :: ByteString)
   (Just bdir) <- fmap headMay $ liftIO $ expandFilePath [Left (dir </> "lib"), Right regex, Left ("lib" </> T.unpack (prettyVer ghcVer))]
   fmap (bdir </>) <$> liftIO (listDirectory bdir)
@@ -845,21 +852,21 @@
 
 
 intoSubdir :: (MonadReader env m, HasLog env, MonadIO m, MonadThrow m, MonadCatch m)
-           => FilePath       -- ^ unpacked tar dir
+           => GHCupPath       -- ^ unpacked tar dir
            -> TarDir         -- ^ how to descend
-           -> Excepts '[TarDirDoesNotExist] m FilePath
+           -> Excepts '[TarDirDoesNotExist] m GHCupPath
 intoSubdir bdir tardir = case tardir of
   RealDir pr -> do
-    whenM (fmap not . liftIO . doesDirectoryExist $ (bdir </> pr))
+    whenM (fmap not . liftIO . doesDirectoryExist $ fromGHCupPath (bdir `appendGHCupPath` pr))
           (throwE $ TarDirDoesNotExist tardir)
-    pure (bdir </> pr)
+    pure (bdir `appendGHCupPath` pr)
   RegexDir r -> do
     let rs = split (`elem` pathSeparators) r
     foldlM
       (\y x ->
-        (handleIO (\_ -> pure []) . liftIO . findFiles y . regex $ x) >>= (\case
+        (handleIO (\_ -> pure []) . liftIO . findFiles (fromGHCupPath y) . regex $ x) >>= (\case
           []      -> throwE $ TarDirDoesNotExist tardir
-          (p : _) -> pure (y </> p)) . sort
+          (p : _) -> pure (y `appendGHCupPath` p)) . sort
       )
       bdir
       rs
@@ -905,7 +912,7 @@
                   => GHCTargetVersion
                   -> m FilePath
 ghcInternalBinDir ver = do
-  ghcdir <- ghcupGHCDir ver
+  ghcdir <- fromGHCupPath <$> ghcupGHCDir ver
   pure (ghcdir </> "bin")
 
 
@@ -1016,6 +1023,28 @@
     !? PatchFailed
 
 
+applyAnyPatch :: ( MonadReader env m
+                 , HasDirs env
+                 , HasLog env
+                 , HasSettings env
+                 , MonadUnliftIO m
+                 , MonadCatch m
+                 , MonadResource m
+                 , MonadThrow m
+                 , MonadMask m
+                 , MonadIO m)
+              => Maybe (Either FilePath [URI])
+              -> FilePath
+              -> Excepts '[PatchFailed, DownloadFailed, DigestError, GPGError] m ()
+applyAnyPatch Nothing _                   = pure ()
+applyAnyPatch (Just (Left pdir)) workdir  = liftE $ applyPatches pdir workdir
+applyAnyPatch (Just (Right uris)) workdir = do
+  tmpUnpack <- fromGHCupPath <$> lift withGHCupTmpDir
+  forM_ uris $ \uri -> do
+    patch <- liftE $ download uri Nothing Nothing tmpUnpack Nothing False
+    liftE $ applyPatch patch workdir
+
+
 -- | https://gitlab.haskell.org/ghc/ghc/-/issues/17353
 darwinNotarization :: (MonadReader env m, HasDirs env, MonadIO m)
                    => Platform
@@ -1029,6 +1058,8 @@
 darwinNotarization _ _ = pure $ Right ()
 
 
+
+
 getChangeLog :: GHCupDownloads -> Tool -> Either Version Tag -> Maybe URI
 getChangeLog dls tool (Left v') =
   preview (ix tool % ix v' % viChangeLog % _Just) dls
@@ -1039,7 +1070,6 @@
 -- | Execute a build action while potentially cleaning up:
 --
 --   1. the build directory, depending on the KeepDirs setting
---   2. the install destination, depending on whether the build failed
 runBuildAction :: ( MonadReader env m
                   , HasDirs env
                   , HasSettings env
@@ -1050,15 +1080,12 @@
                   , MonadFail m
                   , MonadCatch m
                   )
-               => FilePath        -- ^ build directory (cleaned up depending on Settings)
-               -> Maybe FilePath  -- ^ dir to *always* clean up on exception
+               => GHCupPath        -- ^ build directory (cleaned up depending on Settings)
                -> Excepts e m a
                -> Excepts e m a
-runBuildAction bdir instdir action = do
+runBuildAction bdir action = do
   Settings {..} <- lift getSettings
   let exAction = do
-        forM_ instdir $ \dir ->
-          hideError doesNotExistErrorType $ recyclePathForcibly dir
         when (keepDirs == Never)
           $ rmBDir bdir
   v <-
@@ -1070,7 +1097,8 @@
 
 -- | Clean up the given directory if the action fails,
 -- depending on the Settings.
-cleanUpOnError :: ( MonadReader env m
+cleanUpOnError :: forall e m a env .
+                  ( MonadReader env m
                   , HasDirs env
                   , HasSettings env
                   , MonadIO m
@@ -1080,7 +1108,7 @@
                   , MonadFail m
                   , MonadCatch m
                   )
-               => FilePath        -- ^ build directory (cleaned up depending on Settings)
+               => GHCupPath        -- ^ build directory (cleaned up depending on Settings)
                -> Excepts e m a
                -> Excepts e m a
 cleanUpOnError bdir action = do
@@ -1089,13 +1117,33 @@
   flip onException (lift exAction) $ onE_ exAction action
 
 
+-- | Clean up the given directory if the action fails,
+-- depending on the Settings.
+cleanFinally :: ( MonadReader env m
+                  , HasDirs env
+                  , HasSettings env
+                  , MonadIO m
+                  , MonadMask m
+                  , HasLog env
+                  , MonadUnliftIO m
+                  , MonadFail m
+                  , MonadCatch m
+                  )
+               => GHCupPath        -- ^ build directory (cleaned up depending on Settings)
+               -> Excepts e m a
+               -> Excepts e m a
+cleanFinally bdir action = do
+  Settings {..} <- lift getSettings
+  let exAction = when (keepDirs == Never) $ rmBDir bdir
+  flip finally (lift exAction) $ onE_ exAction action
 
+
 -- | Remove a build directory, ignoring if it doesn't exist and gracefully
 -- printing other errors without crashing.
-rmBDir :: (MonadReader env m, HasLog env, MonadUnliftIO m, MonadIO m) => FilePath -> m ()
+rmBDir :: (MonadReader env m, HasLog env, MonadUnliftIO m, MonadIO m) => GHCupPath -> m ()
 rmBDir dir = withRunInIO (\run -> run $
            liftIO $ handleIO (\e -> run $ logWarn $
-               "Couldn't remove build dir " <> T.pack dir <> ", error was: " <> T.pack (displayException e))
+               "Couldn't remove build dir " <> T.pack (fromGHCupPath dir) <> ", error was: " <> T.pack (displayException e))
            $ hideError doesNotExistErrorType
            $ rmPathForcibly dir)
 
@@ -1113,97 +1161,6 @@
     )
 
 
--- | The file extension for executables.
-exeExt :: String
-exeExt
-  | isWindows = ".exe"
-  | otherwise = ""
-
--- | The file extension for executables.
-exeExt' :: ByteString
-exeExt'
-  | isWindows = ".exe"
-  | otherwise = ""
-
-
-
-
--- | On unix, we can use symlinks, so we just get the
--- symbolic link target.
---
--- On windows, we have to emulate symlinks via shims,
--- see 'createLink'.
-getLinkTarget :: FilePath -> IO FilePath
-getLinkTarget fp
-  | isWindows = do
-      content <- readFile (dropExtension fp <.> "shim")
-      [p] <- pure . filter ("path = " `isPrefixOf`) . lines $ content
-      pure $ stripNewline $ dropPrefix "path = " p
-  | otherwise = getSymbolicLinkTarget fp
-
-
--- | Checks whether the path is a link.
-pathIsLink :: FilePath -> IO Bool
-pathIsLink fp
-  | isWindows = doesPathExist (dropExtension fp <.> "shim")
-  | otherwise = pathIsSymbolicLink fp
-
-
-rmLink :: (MonadReader env m, HasDirs env, MonadIO m, MonadMask m) => FilePath -> m ()
-rmLink fp
-  | isWindows = do
-      hideError doesNotExistErrorType . recycleFile $ fp
-      hideError doesNotExistErrorType . recycleFile $ (dropExtension fp <.> "shim")
-  | otherwise = hideError doesNotExistErrorType . recycleFile $ fp
-
-
--- | Creates a symbolic link on unix and a fake symlink on windows for
--- executables, which:
---     1. is a shim exe
---     2. has a corresponding .shim file in the same directory that
---        contains the target
---
--- This overwrites previously existing files.
---
--- On windows, this requires that 'ensureGlobalTools' was run beforehand.
-createLink :: ( MonadMask m
-              , MonadThrow m
-              , HasLog env
-              , MonadIO m
-              , MonadReader env m
-              , HasDirs env
-              , MonadUnliftIO m
-              , MonadFail m
-              )
-           => FilePath      -- ^ path to the target executable
-           -> FilePath      -- ^ path to be created
-           -> m ()
-createLink link exe
-  | isWindows = do
-      dirs <- getDirs
-      let shimGen = cacheDir dirs </> "gs.exe"
-
-      let shim = dropExtension exe <.> "shim"
-          -- For hardlinks, link needs to be absolute.
-          -- If link is relative, it's relative to the target exe.
-          -- Note that (</>) drops lhs when rhs is absolute.
-          fullLink = takeDirectory exe </> link
-          shimContents = "path = " <> fullLink
-
-      logDebug $ "rm -f " <> T.pack exe
-      rmLink exe
-
-      logDebug $ "ln -s " <> T.pack fullLink <> " " <> T.pack exe
-      liftIO $ copyFile shimGen exe
-      liftIO $ writeFile shim shimContents
-  | otherwise = do
-      logDebug $ "rm -f " <> T.pack exe
-      hideError doesNotExistErrorType $ recycleFile exe
-
-      logDebug $ "ln -s " <> T.pack link <> " " <> T.pack exe
-      liftIO $ createFileLink link exe
-
-
 ensureGlobalTools :: ( MonadMask m
                      , MonadThrow m
                      , HasLog env
@@ -1225,8 +1182,8 @@
       let dl = downloadCached' shimDownload (Just "gs.exe") Nothing
       void $ (\DigestError{} -> do
           lift $ logWarn "Digest doesn't match, redownloading gs.exe..."
-          lift $ logDebug ("rm -f " <> T.pack (cacheDir dirs </> "gs.exe"))
-          lift $ hideError doesNotExistErrorType $ recycleFile (cacheDir dirs </> "gs.exe")
+          lift $ logDebug ("rm -f " <> T.pack (fromGHCupPath (cacheDir dirs) </> "gs.exe"))
+          lift $ hideError doesNotExistErrorType $ recycleFile (fromGHCupPath (cacheDir dirs) </> "gs.exe")
           liftE @'[GPGError, DigestError , DownloadFailed] $ dl
         ) `catchE` liftE @'[GPGError, DigestError , DownloadFailed] dl
   | otherwise = pure ()
@@ -1234,14 +1191,17 @@
 
 -- | Ensure ghcup directory structure exists.
 ensureDirectories :: Dirs -> IO ()
-ensureDirectories (Dirs baseDir binDir cacheDir logsDir confDir trashDir) = do
-  createDirRecursive' baseDir
-  createDirRecursive' (baseDir </> "ghc")
+ensureDirectories (Dirs baseDir binDir cacheDir logsDir confDir trashDir dbDir tmpDir) = do
+  createDirRecursive' (fromGHCupPath baseDir)
+  createDirRecursive' (fromGHCupPath baseDir </> "ghc")
+  createDirRecursive' (fromGHCupPath baseDir </> "hls")
   createDirRecursive' binDir
-  createDirRecursive' cacheDir
-  createDirRecursive' logsDir
-  createDirRecursive' confDir
-  createDirRecursive' trashDir
+  createDirRecursive' (fromGHCupPath cacheDir)
+  createDirRecursive' (fromGHCupPath logsDir)
+  createDirRecursive' (fromGHCupPath confDir)
+  createDirRecursive' (fromGHCupPath trashDir)
+  createDirRecursive' (fromGHCupPath dbDir)
+  createDirRecursive' (fromGHCupPath tmpDir)
   pure ()
 
 
@@ -1264,11 +1224,88 @@
 --   3. if it exists and is non-empty -> panic and leave the house
 installDestSanityCheck :: ( MonadIO m
                           , MonadCatch m
+                          , MonadMask m
                           ) =>
                           InstallDirResolved ->
                           Excepts '[DirNotEmpty] m ()
 installDestSanityCheck (IsolateDirResolved isoDir) = do
   hideErrorDef [doesNotExistErrorType] () $ do
-    contents <- liftIO $ getDirectoryContentsRecursive isoDir
-    unless (null contents) (throwE $ DirNotEmpty isoDir)
+    empty' <- liftIO $ S.null $ getDirectoryContentsRecursiveUnsafe isoDir
+    when (not empty') (throwE $ DirNotEmpty isoDir)
 installDestSanityCheck _ = pure ()
+
+
+-- | Returns 'Nothing' for legacy installs.
+getInstalledFiles :: ( MonadIO m
+                     , MonadCatch m
+                     , MonadReader env m
+                     , HasDirs env
+                     , MonadFail m
+                     )
+                  => Tool
+                  -> GHCTargetVersion
+                  -> m (Maybe [FilePath])
+getInstalledFiles t v' = hideErrorDef [doesNotExistErrorType] Nothing $ do
+  f <- recordedInstallationFile t v'
+  (force -> !c) <- liftIO
+    (readFile f >>= evaluate)
+  pure (Just $ lines c)
+
+
+-- | Warn if the installed and set HLS is not compatible with the installed and
+-- set GHC version.
+warnAboutHlsCompatibility :: ( MonadReader env m
+                             , HasDirs env
+                             , HasLog env
+                             , MonadThrow m
+                             , MonadCatch m
+                             , MonadIO m
+                             )
+                          => m ()
+warnAboutHlsCompatibility = do
+  supportedGHC <- hlsGHCVersions
+  currentGHC   <- fmap _tvVersion <$> ghcSet Nothing
+  currentHLS   <- hlsSet
+
+  case (currentGHC, currentHLS) of
+    (Just gv, Just hv) | gv `notElem` supportedGHC -> do
+      logWarn $
+        "GHC " <> T.pack (prettyShow gv) <> " is not compatible with " <>
+        "Haskell Language Server " <> T.pack (prettyShow hv) <> "." <> "\n" <>
+        "Haskell IDE support may not work until this is fixed." <> "\n" <>
+        "Install a different HLS version, or install and set one of the following GHCs:" <> "\n" <>
+        T.pack (prettyShow supportedGHC)
+
+    _ -> return ()
+
+
+
+    -----------
+    --[ Git ]--
+    -----------
+
+
+
+isCommitHash :: String -> Bool
+isCommitHash str' = let hex = all isHexDigit str'
+                        len = length str'
+                    in hex && len == 40
+
+
+gitOut :: (MonadReader env m, HasLog env, MonadIO m) => [String] -> FilePath -> Excepts '[ProcessError] m T.Text
+gitOut args dir = do
+  CapturedProcess {..} <- lift $ executeOut "git" args (Just dir)
+  case _exitCode of
+    ExitSuccess   -> pure $ T.pack $ stripNewlineEnd $ T.unpack $ decUTF8Safe' _stdOut
+    ExitFailure c -> do
+      let pe = NonZeroExit c "git" args
+      lift $ logDebug $ T.pack (prettyShow pe)
+      throwE pe
+
+processBranches :: T.Text -> [String]
+processBranches str' = let lines'   = lines (T.unpack str')
+                           words'   = fmap words lines'
+                           refs     = catMaybes $ fmap (`atMay` 1) words'
+                           branches = catMaybes $ fmap (stripPrefix "refs/heads/") $ filter (isPrefixOf "refs/heads/") refs
+                       in branches
+
diff --git a/lib/GHCup/Utils.hs-boot b/lib/GHCup/Utils.hs-boot
deleted file mode 100644
--- a/lib/GHCup/Utils.hs-boot
+++ /dev/null
@@ -1,4 +0,0 @@
-module GHCup.Utils where
-
-getLinkTarget :: FilePath -> IO FilePath
-pathIsLink :: FilePath -> IO Bool
diff --git a/lib/GHCup/Utils/Dirs.hs b/lib/GHCup/Utils/Dirs.hs
--- a/lib/GHCup/Utils/Dirs.hs
+++ b/lib/GHCup/Utils/Dirs.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE OverloadedStrings     #-}
 {-# LANGUAGE FlexibleContexts      #-}
 {-# LANGUAGE ViewPatterns          #-}
+{-# LANGUAGE QuasiQuotes           #-}
 
 {-|
 Module      : GHCup.Utils.Dirs
@@ -30,6 +31,74 @@
   , getConfigFilePath
   , useXDG
   , cleanupTrash
+
+  , GHCupPath
+  , appendGHCupPath
+  , fromGHCupPath
+  , createTempGHCupDirectory
+  , getGHCupTmpDirs
+
+  , removeDirectory
+  , removeDirectoryRecursive
+  , removePathForcibly
+
+  -- System.Directory re-exports
+  , createDirectory
+  , createDirectoryIfMissing
+  , renameDirectory
+  , listDirectory
+  , getDirectoryContents
+  , getCurrentDirectory
+  , setCurrentDirectory
+  , withCurrentDirectory
+  , getHomeDirectory
+  , XdgDirectory(..)
+  , getXdgDirectory
+  , XdgDirectoryList(..)
+  , getXdgDirectoryList
+  , getAppUserDataDirectory
+  , getUserDocumentsDirectory
+  , getTemporaryDirectory
+  , removeFile
+  , renameFile
+  , renamePath
+  , getFileSize
+  , canonicalizePath
+  , makeAbsolute
+  , makeRelativeToCurrentDirectory
+  , doesPathExist
+  , doesFileExist
+  , doesDirectoryExist
+  , findExecutable
+  , findExecutables
+  , findExecutablesInDirectories
+  , findFile
+  , findFileWith
+  , findFilesWith
+  , exeExtension
+  , createFileLink
+  , createDirectoryLink
+  , removeDirectoryLink
+  , pathIsSymbolicLink
+  , getSymbolicLinkTarget
+  , Permissions
+  , emptyPermissions
+  , readable
+  , writable
+  , executable
+  , searchable
+  , setOwnerReadable
+  , setOwnerWritable
+  , setOwnerExecutable
+  , setOwnerSearchable
+  , getPermissions
+  , setPermissions
+  , copyPermissions
+  , getAccessTime
+  , getModificationTime
+  , setAccessTime
+  , setModificationTime
+  , isSymbolicLink
   )
 where
 
@@ -38,35 +107,86 @@
 import           GHCup.Types
 import           GHCup.Types.JSON               ( )
 import           GHCup.Types.Optics
-import           GHCup.Utils.MegaParsec
-import           GHCup.Utils.Logger
-import           GHCup.Utils.Prelude
+import           GHCup.Prelude.MegaParsec
+import           GHCup.Prelude.File.Search
+import           GHCup.Prelude.String.QQ
+import           GHCup.Prelude.Logger.Internal (logWarn, logDebug)
+#if defined(IS_WINDOWS)
+import           GHCup.Prelude.Windows ( isWindows )
+#else
+import           GHCup.Prelude.Posix   ( isWindows )
+#endif
 
+import           Control.DeepSeq (NFData, rnf)
 import           Control.Exception.Safe
 import           Control.Monad
 import           Control.Monad.IO.Unlift
 import           Control.Monad.Reader
 import           Control.Monad.Trans.Resource hiding (throwM)
+import           Data.List
+import           Data.ByteString                ( ByteString )
 import           Data.Bifunctor
 import           Data.Maybe
 import           Data.Versions
 import           GHC.IO.Exception               ( IOErrorType(NoSuchThing) )
 import           Haskus.Utils.Variant.Excepts
 import           Optics
-import           System.Directory                                                
-import           System.DiskSpace                                                
+import           Safe
+import           System.Directory hiding ( removeDirectory
+                                         , removeDirectoryRecursive
+                                         , removePathForcibly
+                                         , findFiles
+                                         )
+import qualified System.Directory              as SD
+
 import           System.Environment
 import           System.FilePath
 import           System.IO.Temp
+import           Text.Regex.Posix
 
 import qualified Data.ByteString               as BS
 import qualified Data.Text                     as T
 import qualified Data.Yaml.Aeson               as Y
 import qualified Text.Megaparsec               as MP
-import Control.Concurrent (threadDelay)
+import System.IO.Error (ioeGetErrorType)
 
 
 
+    ---------------------------
+    --[ GHCupPath utilities ]--
+    ---------------------------
+
+-- | A 'GHCupPath' is a safe sub-path that can be recursively deleted.
+--
+-- The constructor is not exported.
+newtype GHCupPath = GHCupPath FilePath
+  deriving (Show, Eq, Ord)
+
+instance NFData GHCupPath where
+  rnf (GHCupPath fp) = rnf fp
+
+appendGHCupPath :: GHCupPath -> FilePath -> GHCupPath
+appendGHCupPath (GHCupPath gp) fp = GHCupPath (gp </> fp)
+
+fromGHCupPath :: GHCupPath -> FilePath
+fromGHCupPath (GHCupPath gp) = gp
+
+createTempGHCupDirectory :: GHCupPath -> FilePath -> IO GHCupPath
+createTempGHCupDirectory (GHCupPath gp) d = GHCupPath <$> createTempDirectory gp d
+
+
+getGHCupTmpDirs :: IO [GHCupPath]
+getGHCupTmpDirs = do
+  tmpdir <- fromGHCupPath <$> ghcupTMPDir
+  ghcup_dirs <- handleIO (\_ -> pure []) $ findFiles
+    tmpdir
+    (makeRegexOpts compExtended
+                   execBlank
+                   ([s|^ghcup-.*$|] :: ByteString)
+    )
+  pure (fmap (\p -> GHCupPath (tmpdir </> p)) $ filter (maybe False ("ghcup-" `isPrefixOf`) . lastMay . splitPath) ghcup_dirs)
+
+
     ------------------------------
     --[ GHCup base directories ]--
     ------------------------------
@@ -76,11 +196,11 @@
 --
 -- If 'GHCUP_USE_XDG_DIRS' is set (to anything),
 -- then uses 'XDG_DATA_HOME/ghcup' as per xdg spec.
-ghcupBaseDir :: IO FilePath
+ghcupBaseDir :: IO GHCupPath
 ghcupBaseDir
   | isWindows = do
       bdir <- fromMaybe "C:\\" <$> lookupEnv "GHCUP_INSTALL_BASE_PREFIX"
-      pure (bdir </> "ghcup")
+      pure (GHCupPath (bdir </> "ghcup"))
   | otherwise = do
       xdg <- useXDG
       if xdg
@@ -90,19 +210,19 @@
             Nothing -> do
               home <- liftIO getHomeDirectory
               pure (home </> ".local" </> "share")
-          pure (bdir </> "ghcup")
+          pure (GHCupPath (bdir </> "ghcup"))
         else do
           bdir <- lookupEnv "GHCUP_INSTALL_BASE_PREFIX" >>= \case
             Just r  -> pure r
             Nothing -> liftIO getHomeDirectory
-          pure (bdir </> ".ghcup")
+          pure (GHCupPath (bdir </> ".ghcup"))
 
 
 -- | ~/.ghcup by default
 --
 -- If 'GHCUP_USE_XDG_DIRS' is set (to anything),
 -- then uses 'XDG_CONFIG_HOME/ghcup' as per xdg spec.
-ghcupConfigDir :: IO FilePath
+ghcupConfigDir :: IO GHCupPath
 ghcupConfigDir
   | isWindows = ghcupBaseDir
   | otherwise = do
@@ -114,12 +234,12 @@
             Nothing -> do
               home <- liftIO getHomeDirectory
               pure (home </> ".config")
-          pure (bdir </> "ghcup")
+          pure (GHCupPath (bdir </> "ghcup"))
         else do
           bdir <- lookupEnv "GHCUP_INSTALL_BASE_PREFIX" >>= \case
             Just r  -> pure r
             Nothing -> liftIO getHomeDirectory
-          pure (bdir </> ".ghcup")
+          pure (GHCupPath (bdir </> ".ghcup"))
 
 
 -- | If 'GHCUP_USE_XDG_DIRS' is set (to anything),
@@ -127,7 +247,7 @@
 -- (which, sadly is not strictly xdg spec).
 ghcupBinDir :: IO FilePath
 ghcupBinDir
-  | isWindows = ghcupBaseDir <&> (</> "bin")
+  | isWindows = (fromGHCupPath <$> ghcupBaseDir) <&> (</> "bin")
   | otherwise = do
       xdg <- useXDG
       if xdg
@@ -137,16 +257,16 @@
             Nothing -> do
               home <- liftIO getHomeDirectory
               pure (home </> ".local" </> "bin")
-        else ghcupBaseDir <&> (</> "bin")
+        else (fromGHCupPath <$> ghcupBaseDir) <&> (</> "bin")
 
 
 -- | Defaults to '~/.ghcup/cache'.
 --
 -- If 'GHCUP_USE_XDG_DIRS' is set (to anything),
 -- then uses 'XDG_CACHE_HOME/ghcup' as per xdg spec.
-ghcupCacheDir :: IO FilePath
+ghcupCacheDir :: IO GHCupPath
 ghcupCacheDir
-  | isWindows = ghcupBaseDir <&> (</> "cache")
+  | isWindows = ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "cache"))
   | otherwise = do
       xdg <- useXDG
       if xdg
@@ -156,17 +276,17 @@
             Nothing -> do
               home <- liftIO getHomeDirectory
               pure (home </> ".cache")
-          pure (bdir </> "ghcup")
-        else ghcupBaseDir <&> (</> "cache")
+          pure (GHCupPath (bdir </> "ghcup"))
+        else ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "cache"))
 
 
 -- | Defaults to '~/.ghcup/logs'.
 --
 -- If 'GHCUP_USE_XDG_DIRS' is set (to anything),
 -- then uses 'XDG_CACHE_HOME/ghcup/logs' as per xdg spec.
-ghcupLogsDir :: IO FilePath
+ghcupLogsDir :: IO GHCupPath
 ghcupLogsDir
-  | isWindows = ghcupBaseDir <&> (</> "logs")
+  | isWindows = ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "logs"))
   | otherwise = do
       xdg <- useXDG
       if xdg
@@ -176,17 +296,56 @@
             Nothing -> do
               home <- liftIO getHomeDirectory
               pure (home </> ".cache")
-          pure (bdir </> "ghcup" </> "logs")
-        else ghcupBaseDir <&> (</> "logs")
+          pure (GHCupPath (bdir </> "ghcup" </> "logs"))
+        else ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "logs"))
 
 
+-- | Defaults to '~/.ghcup/db.
+--
+-- If 'GHCUP_USE_XDG_DIRS' is set (to anything),
+-- then uses 'XDG_CACHE_HOME/ghcup/db as per xdg spec.
+ghcupDbDir :: IO GHCupPath
+ghcupDbDir
+  | isWindows = ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "db"))
+  | otherwise = do
+      xdg <- useXDG
+      if xdg
+        then do
+          bdir <- lookupEnv "XDG_CACHE_HOME" >>= \case
+            Just r  -> pure r
+            Nothing -> do
+              home <- liftIO getHomeDirectory
+              pure (home </> ".cache")
+          pure (GHCupPath (bdir </> "ghcup" </> "db"))
+        else ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "db"))
+
+
 -- | '~/.ghcup/trash'.
 -- Mainly used on windows to improve file removal operations
-ghcupRecycleDir :: IO FilePath
-ghcupRecycleDir = ghcupBaseDir <&> (</> "trash")
+ghcupRecycleDir :: IO GHCupPath
+ghcupRecycleDir = ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "trash"))
 
 
+-- | Defaults to '~/.ghcup/tmp.
+--
+-- If 'GHCUP_USE_XDG_DIRS' is set (to anything),
+-- then uses 'XDG_CACHE_HOME/ghcup/tmp as per xdg spec.
+ghcupTMPDir :: IO GHCupPath
+ghcupTMPDir
+  | isWindows = ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "tmp"))
+  | otherwise = do
+      xdg <- useXDG
+      if xdg
+        then do
+          bdir <- lookupEnv "XDG_CACHE_HOME" >>= \case
+            Just r  -> pure r
+            Nothing -> do
+              home <- liftIO getHomeDirectory
+              pure (home </> ".cache")
+          pure (GHCupPath (bdir </> "ghcup" </> "tmp"))
+        else ghcupBaseDir <&> (\(GHCupPath gp) -> GHCupPath (gp </> "tmp"))
 
+
 getAllDirs :: IO Dirs
 getAllDirs = do
   baseDir    <- ghcupBaseDir
@@ -195,6 +354,8 @@
   logsDir    <- ghcupLogsDir
   confDir    <- ghcupConfigDir
   recycleDir <- ghcupRecycleDir
+  tmpDir     <- ghcupTMPDir
+  dbDir      <- ghcupDbDir
   pure Dirs { .. }
 
 
@@ -206,16 +367,21 @@
 getConfigFilePath :: (MonadIO m) => m FilePath
 getConfigFilePath = do
   confDir <- liftIO ghcupConfigDir
-  pure $ confDir </> "config.yaml"
+  pure $ fromGHCupPath confDir </> "config.yaml"
 
 ghcupConfigFile :: (MonadIO m)
                 => Excepts '[JSONError] m UserSettings
 ghcupConfigFile = do
   filepath <- getConfigFilePath
-  contents <- liftIO $ handleIO' NoSuchThing (\_ -> pure Nothing) $ Just <$> BS.readFile filepath
+  contents <- liftIO $ handleIO (\e -> if NoSuchThing == ioeGetErrorType e then pure Nothing else liftIO $ ioError e) $ Just <$> BS.readFile filepath
   case contents of
       Nothing -> pure defaultUserSettings
-      Just contents' -> lE' JSONDecodeError . first displayException . Y.decodeEither' $ contents'
+      Just contents' -> liftE
+        . veitherToExcepts @_ @'[JSONError]
+        . either (VLeft . V) VRight
+        . first (JSONDecodeError . displayException)
+        . Y.decodeEither'
+        $ contents'
 
 
     -------------------------
@@ -224,10 +390,10 @@
 
 
 -- | ~/.ghcup/ghc by default.
-ghcupGHCBaseDir :: (MonadReader env m, HasDirs env) => m FilePath
+ghcupGHCBaseDir :: (MonadReader env m, HasDirs env) => m GHCupPath
 ghcupGHCBaseDir = do
   Dirs {..}  <- getDirs
-  pure (baseDir </> "ghc")
+  pure (baseDir `appendGHCupPath` "ghc")
 
 
 -- | Gets '~/.ghcup/ghc/<ghcupGHCDir>'.
@@ -236,11 +402,11 @@
 --   * 8.8.4
 ghcupGHCDir :: (MonadReader env m, HasDirs env, MonadThrow m)
             => GHCTargetVersion
-            -> m FilePath
+            -> m GHCupPath
 ghcupGHCDir ver = do
   ghcbasedir <- ghcupGHCBaseDir
   let verdir = T.unpack $ tVerToText ver
-  pure (ghcbasedir </> verdir)
+  pure (ghcbasedir `appendGHCupPath` verdir)
 
 
 -- | See 'ghcupToolParser'.
@@ -252,21 +418,28 @@
 parseGHCupHLSDir (T.pack -> fp) =
   throwEither $ MP.parse version' "" fp
 
+-- TODO: inlined from GHCup.Prelude
+throwEither :: (Exception a, MonadThrow m) => Either a b -> m b
+throwEither a = case a of
+  Left  e -> throwM e
+  Right r -> pure r
+
 -- | ~/.ghcup/hls by default, for new-style installs.
-ghcupHLSBaseDir :: (MonadReader env m, HasDirs env) => m FilePath
+ghcupHLSBaseDir :: (MonadReader env m, HasDirs env) => m GHCupPath
 ghcupHLSBaseDir = do
   Dirs {..}  <- getDirs
-  pure (baseDir </> "hls")
+  pure (baseDir `appendGHCupPath` "hls")
 
 -- | Gets '~/.ghcup/hls/<hls-ver>' for new-style installs.
 ghcupHLSDir :: (MonadReader env m, HasDirs env, MonadThrow m)
             => Version
-            -> m FilePath
+            -> m GHCupPath
 ghcupHLSDir ver = do
   basedir <- ghcupHLSBaseDir
   let verdir = T.unpack $ prettyVer ver
-  pure (basedir </> verdir)
+  pure (basedir `appendGHCupPath` verdir)
 
+
 mkGhcupTmpDir :: ( MonadReader env m
                  , HasDirs env
                  , MonadUnliftIO m
@@ -275,31 +448,10 @@
                  , MonadThrow m
                  , MonadMask m
                  , MonadIO m)
-              => m FilePath
-mkGhcupTmpDir = do
-  tmpdir <- liftIO getCanonicalTemporaryDirectory
-
-  let minSpace = 5000 -- a rough guess, aight?
-  space <- handleIO (\_ -> pure Nothing) $ fmap Just $ liftIO $ getAvailSpace tmpdir
-  when (maybe False (toBytes minSpace >) space) $ do
-    logWarn ("Possibly insufficient disk space on "
-      <> T.pack tmpdir
-      <> ". At least "
-      <> T.pack (show minSpace)
-      <> " MB are recommended, but only "
-      <> toMB (fromJust space)
-      <> " are free. Consider freeing up disk space or setting TMPDIR env variable.")
-    logWarn
-      "...waiting for 10 seconds before continuing anyway, you can still abort..."
-    liftIO $ threadDelay 10000000 -- give the user a sec to intervene
-
-  liftIO $ createTempDirectory tmpdir "ghcup"
- where
-  toBytes mb = mb * 1024 * 1024
-  toMB b = T.pack $ show (truncate' (fromIntegral b / (1024 * 1024) :: Double) 2)
-  truncate' :: Double -> Int -> Double
-  truncate' x n = fromIntegral (floor (x * t) :: Integer) / t
-      where t = 10^n
+              => m GHCupPath
+mkGhcupTmpDir = GHCupPath <$> do
+  Dirs { tmpDir } <- getDirs
+  liftIO $ createTempDirectory (fromGHCupPath tmpDir) "ghcup"
 
 
 withGHCupTmpDir :: ( MonadReader env m
@@ -312,15 +464,15 @@
                    , MonadThrow m
                    , MonadMask m
                    , MonadIO m)
-                => m FilePath
+                => m GHCupPath
 withGHCupTmpDir = snd <$> withRunInIO (\run ->
   run
     $ allocate
         (run mkGhcupTmpDir)
         (\fp ->
             handleIO (\e -> run
-                $ logDebug ("Resource cleanup failed for " <> T.pack fp <> ", error was: " <> T.pack (displayException e)))
-            . rmPathForcibly
+                $ logDebug ("Resource cleanup failed for " <> T.pack (fromGHCupPath fp) <> ", error was: " <> T.pack (displayException e)))
+            . removePathForcibly
             $ fp))
 
 
@@ -360,12 +512,28 @@
              => m ()
 cleanupTrash = do
   Dirs { recycleDir } <- getDirs
-  contents <- liftIO $ listDirectory recycleDir
+  contents <- liftIO $ listDirectory (fromGHCupPath recycleDir)
   if null contents
   then pure ()
   else do
-    logWarn ("Removing leftover files in " <> T.pack recycleDir)
+    logWarn ("Removing leftover files in " <> T.pack (fromGHCupPath recycleDir))
     forM_ contents (\fp -> handleIO (\e ->
         logDebug ("Resource cleanup failed for " <> T.pack fp <> ", error was: " <> T.pack (displayException e))
-      ) $ liftIO $ removePathForcibly (recycleDir </> fp))
+      ) $ liftIO $ removePathForcibly (recycleDir `appendGHCupPath` fp))
+
+
+
+-- System.Directory re-exports with GHCupPath
+
+removeDirectory :: GHCupPath -> IO ()
+removeDirectory (GHCupPath fp) = SD.removeDirectory fp
+
+removeDirectoryRecursive :: GHCupPath -> IO ()
+removeDirectoryRecursive (GHCupPath fp) = SD.removeDirectoryRecursive fp
+
+removePathForcibly :: GHCupPath -> IO ()
+removePathForcibly (GHCupPath fp) = SD.removePathForcibly fp
+
+
+
 
diff --git a/lib/GHCup/Utils/Dirs.hs-boot b/lib/GHCup/Utils/Dirs.hs-boot
new file mode 100644
--- /dev/null
+++ b/lib/GHCup/Utils/Dirs.hs-boot
@@ -0,0 +1,37 @@
+module GHCup.Utils.Dirs
+ ( GHCupPath
+ , appendGHCupPath
+ , fromGHCupPath
+ , createTempGHCupDirectory
+ , removeDirectory
+ , removeDirectoryRecursive
+ , removePathForcibly
+ )
+ where
+
+import Control.DeepSeq (NFData)
+
+
+-- | A 'GHCupPath' is a safe sub-path that can be recursively deleted.
+newtype GHCupPath = GHCupPath FilePath
+
+instance Show GHCupPath where
+
+instance Eq GHCupPath where
+
+instance Ord GHCupPath where
+
+instance NFData GHCupPath where
+
+appendGHCupPath :: GHCupPath -> FilePath -> GHCupPath
+
+fromGHCupPath :: GHCupPath -> FilePath
+
+createTempGHCupDirectory :: GHCupPath -> FilePath -> IO GHCupPath
+
+removeDirectory :: GHCupPath -> IO ()
+
+removeDirectoryRecursive :: GHCupPath -> IO ()
+
+removePathForcibly :: GHCupPath -> IO ()
+
diff --git a/lib/GHCup/Utils/File.hs b/lib/GHCup/Utils/File.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/File.hs
+++ /dev/null
@@ -1,17 +0,0 @@
-{-# LANGUAGE CPP #-}
-
-module GHCup.Utils.File (
-  module GHCup.Utils.File.Common,
-#if IS_WINDOWS
-  module GHCup.Utils.File.Windows
-#else
-  module GHCup.Utils.File.Posix
-#endif
-) where
-
-import GHCup.Utils.File.Common
-#if IS_WINDOWS
-import GHCup.Utils.File.Windows
-#else
-import GHCup.Utils.File.Posix
-#endif
diff --git a/lib/GHCup/Utils/File/Common.hs b/lib/GHCup/Utils/File/Common.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/File/Common.hs
+++ /dev/null
@@ -1,111 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE FlexibleContexts  #-}
-
-module GHCup.Utils.File.Common (
-  module GHCup.Utils.File.Common
-  , ProcessError(..)
-  , CapturedProcess(..)
-  ) where
-
-import           GHCup.Utils.Prelude
-import           GHCup.Types(ProcessError(..), CapturedProcess(..))
-
-import           Control.Monad.Reader
-import           Data.Maybe
-import           Data.Text               ( Text )
-import           Data.Void
-import           GHC.IO.Exception
-import           Optics                  hiding ((<|), (|>))
-import           System.Directory        hiding (findFiles)
-import           System.FilePath
-import           Text.PrettyPrint.HughesPJClass hiding ( (<>) )
-import           Text.Regex.Posix
-
-import qualified Data.Text                     as T
-import qualified Data.ByteString.Lazy          as BL
-import qualified Text.Megaparsec               as MP
-
-
-
--- | Search for a file in the search paths.
---
--- Catches `PermissionDenied` and `NoSuchThing` and returns `Nothing`.
-searchPath :: [FilePath] -> FilePath -> IO (Maybe FilePath)
-searchPath paths needle = go paths
- where
-  go [] = pure Nothing
-  go (x : xs) =
-    hideErrorDefM [InappropriateType, PermissionDenied, NoSuchThing] (go xs)
-      $ do
-          contents <- listDirectory x
-          findM (isMatch x) contents >>= \case
-            Just _ -> pure $ Just (x </> needle)
-            Nothing -> go xs
-  isMatch basedir p = do
-    if p == needle
-      then isExecutable (basedir </> needle)
-      else pure False
-
-  isExecutable :: FilePath -> IO Bool
-  isExecutable file = executable <$> getPermissions file
-
-
--- | Check wether a binary is shadowed by another one that comes before
--- it in PATH. Returns the path to said binary, if any.
-isShadowed :: FilePath -> IO (Maybe FilePath)
-isShadowed p = do
-  let dir = takeDirectory p
-  let fn = takeFileName p
-  spaths <- liftIO getSearchPath
-  if dir `elem` spaths
-  then do
-    let shadowPaths = takeWhile (/= dir) spaths
-    searchPath shadowPaths fn
-  else pure Nothing
-
-
--- | Check whether the binary is in PATH. This returns only `True`
--- if the directory containing the binary is part of PATH.
-isInPath :: FilePath -> IO Bool
-isInPath p = do
-  let dir = takeDirectory p
-  let fn = takeFileName p
-  spaths <- liftIO getSearchPath
-  if dir `elem` spaths
-  then isJust <$> searchPath [dir] fn
-  else pure False
-
-
--- | Follows the first match in case of Regex.
-expandFilePath :: [Either FilePath Regex] -> IO [FilePath]
-expandFilePath = go ""
- where
-  go :: FilePath -> [Either FilePath Regex] -> IO [FilePath]
-  go p [] = pure [p]
-  go p (x:xs) = do
-    case x of
-      Left s -> go (p </> s) xs
-      Right regex -> do
-        fps <- findFiles p regex
-        res <- forM fps $ \fp -> go (p </> fp) xs
-        pure $ mconcat res
-
-
-findFiles :: FilePath -> Regex -> IO [FilePath]
-findFiles path regex = do
-  contents <- listDirectory path
-  pure $ filter (match regex) contents
-
-findFilesDeep :: FilePath -> Regex -> IO [FilePath]
-findFilesDeep path regex = do
-  contents <- getDirectoryContentsRecursive path
-  pure $ filter (match regex) contents
-
-findFiles' :: FilePath -> MP.Parsec Void Text a -> IO [FilePath]
-findFiles' path parser = do
-  contents <- listDirectory path
-  pure $ filter (\fp -> either (const False) (const True) $ MP.parse parser "" (T.pack fp)) contents
-
-
-checkFileAlreadyExists :: (MonadIO m) => FilePath -> m Bool
-checkFileAlreadyExists fp = liftIO $ doesFileExist fp
diff --git a/lib/GHCup/Utils/File/Common.hs-boot b/lib/GHCup/Utils/File/Common.hs-boot
deleted file mode 100644
--- a/lib/GHCup/Utils/File/Common.hs-boot
+++ /dev/null
@@ -1,5 +0,0 @@
-module GHCup.Utils.File.Common where
-
-import           Text.Regex.Posix
-
-findFiles :: FilePath -> Regex -> IO [FilePath]
diff --git a/lib/GHCup/Utils/File/Posix.hs b/lib/GHCup/Utils/File/Posix.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/File/Posix.hs
+++ /dev/null
@@ -1,401 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE FlexibleContexts  #-}
-
-{-|
-Module      : GHCup.Utils.File.Posix
-Description : File and unix APIs
-Copyright   : (c) Julian Ospald, 2020
-License     : LGPL-3.0
-Maintainer  : hasufell@hasufell.de
-Stability   : experimental
-Portability : POSIX
-
-This module handles file and executable handling.
-Some of these functions use sophisticated logging.
--}
-module GHCup.Utils.File.Posix where
-
-import           GHCup.Utils.File.Common
-import           GHCup.Utils.Prelude
-import           GHCup.Utils.Logger
-import           GHCup.Types
-import           GHCup.Types.Optics
-
-import           Control.Concurrent
-import           Control.Concurrent.Async
-import           Control.Exception              ( evaluate )
-import           Control.Exception.Safe
-import           Control.Monad
-import           Control.Monad.Reader
-import           Control.Monad.Trans.State.Strict
-import           Data.ByteString                ( ByteString )
-import           Data.Foldable
-import           Data.IORef
-import           Data.Sequence                  ( Seq, (|>) )
-import           Data.List
-import           Data.Word8
-import           GHC.IO.Exception
-import           System.IO                      ( stderr )
-import           System.IO.Error
-import           System.FilePath
-import           System.Directory
-import           System.Posix.Directory
-import           System.Posix.Files
-import           System.Posix.IO
-import           System.Posix.Process           ( ProcessStatus(..) )
-import           System.Posix.Types
-
-
-import qualified Control.Exception             as EX
-import qualified Data.Sequence                 as Sq
-import qualified Data.Text                     as T
-import qualified Data.Text.Encoding            as E
-import qualified System.Posix.Process          as SPP
-import qualified System.Console.Terminal.Size  as TP
-import qualified Data.ByteString               as BS
-import qualified Data.ByteString.Lazy          as BL
-import qualified "unix-bytestring" System.Posix.IO.ByteString
-                                               as SPIB
-
-
-
--- | Execute the given command and collect the stdout, stderr and the exit code.
--- The command is run in a subprocess.
-executeOut :: MonadIO m
-           => FilePath          -- ^ command as filename, e.g. 'ls'
-           -> [String]          -- ^ arguments to the command
-           -> Maybe FilePath    -- ^ chdir to this path
-           -> m CapturedProcess
-executeOut path args chdir = liftIO $ captureOutStreams $ do
-  maybe (pure ()) changeWorkingDirectory chdir
-  SPP.executeFile path True args Nothing
-
-
-execLogged :: ( MonadReader env m
-              , HasSettings env
-              , HasLog env
-              , HasDirs env
-              , MonadIO m
-              , MonadThrow m)
-           => FilePath         -- ^ thing to execute
-           -> [String]         -- ^ args for the thing
-           -> Maybe FilePath   -- ^ optionally chdir into this
-           -> FilePath         -- ^ log filename (opened in append mode)
-           -> Maybe [(String, String)] -- ^ optional environment
-           -> m (Either ProcessError ())
-execLogged exe args chdir lfile env = do
-  Settings {..} <- getSettings
-  Dirs {..} <- getDirs
-  logDebug $ T.pack $ "Running " <> exe <> " with arguments " <> show args
-  let logfile = logsDir </> lfile <> ".log"
-  liftIO $ bracket (openFd logfile WriteOnly (Just newFilePerms) defaultFileFlags{ append = True })
-                   closeFd
-                   (action verbose noColor)
- where
-  action verbose no_color fd = do
-    actionWithPipes $ \(stdoutRead, stdoutWrite) -> do
-      -- start the thread that logs to stdout
-      pState <- newEmptyMVar
-      done   <- newEmptyMVar
-      void
-        $ forkIO
-        $ EX.handle (\(_ :: IOException) -> pure ())
-        $ EX.finally
-            (if verbose
-              then tee fd stdoutRead
-              else printToRegion fd stdoutRead 6 pState no_color
-            )
-            (putMVar done ())
-
-      -- fork the subprocess
-      pid <- SPP.forkProcess $ do
-        void $ dupTo stdoutWrite stdOutput
-        void $ dupTo stdoutWrite stdError
-        closeFd stdoutRead
-        closeFd stdoutWrite
-
-        -- execute the action
-        maybe (pure ()) changeWorkingDirectory chdir
-        void $ SPP.executeFile exe (not ("./" `isPrefixOf` exe)) args env
-
-      closeFd stdoutWrite
-
-      -- wait for the subprocess to finish
-      e <- toProcessError exe args <$!> SPP.getProcessStatus True True pid
-      putMVar pState (either (const False) (const True) e)
-
-      void $ race (takeMVar done) (threadDelay (1000000 * 3))
-      closeFd stdoutRead
-
-      pure e
-
-  tee :: Fd -> Fd -> IO ()
-  tee fileFd = readTilEOF lineAction
-
-   where
-    lineAction :: ByteString -> IO ()
-    lineAction bs' = do
-      void $ SPIB.fdWrite fileFd (bs' <> "\n")
-      void $ SPIB.fdWrite stdOutput (bs' <> "\n")
-
-  -- Reads fdIn and logs the output in a continous scrolling area
-  -- of 'size' terminal lines. Also writes to a log file.
-  printToRegion :: Fd -> Fd -> Int -> MVar Bool -> Bool -> IO ()
-  printToRegion fileFd fdIn size pState no_color = do
-    -- init region
-    forM_ [1..size] $ \_ -> BS.hPut stderr "\n"
-
-    void $ flip runStateT mempty
-      $ do
-        handle
-          (\(ex :: SomeException) -> do
-            ps <- liftIO $ takeMVar pState
-            when ps (liftIO $ BS.hPut stderr (pos1 <> moveLineUp size <> clearScreen))
-            throw ex
-          ) $ readTilEOF lineAction fdIn
-
-   where
-    clearScreen :: ByteString
-    clearScreen = "\x1b[0J"
-    clearLine :: ByteString
-    clearLine = "\x1b[2K"
-    moveLineUp :: Int -> ByteString
-    moveLineUp n = "\x1b[" <> E.encodeUtf8 (T.pack (show n)) <> "A"
-    moveLineDown :: Int -> ByteString
-    moveLineDown n = "\x1b[" <> E.encodeUtf8 (T.pack (show n)) <> "B"
-    pos1 :: ByteString
-    pos1 = "\r"
-    overwriteNthLine :: Int -> ByteString -> ByteString
-    overwriteNthLine n str = pos1 <> moveLineUp n <> clearLine <> str <> moveLineDown n <> pos1
-
-    blue :: ByteString -> ByteString
-    blue bs 
-      | no_color = bs
-      | otherwise = "\x1b[0;34m" <> bs <> "\x1b[0m"
-
-    -- action to perform line by line
-    lineAction :: (MonadMask m, MonadIO m)
-               => ByteString
-               -> StateT (Seq ByteString) m ()
-    lineAction = \bs' -> do
-      void $ liftIO $ SPIB.fdWrite fileFd (bs' <> "\n")
-      modify (swapRegs bs')
-      liftIO TP.size >>= \case
-        Nothing -> pure ()
-        Just (TP.Window _ w) -> do
-          regs <- get
-          liftIO $ forM_ (Sq.zip regs (Sq.fromList [0..(Sq.length regs - 1)])) $ \(bs, i) -> do
-              BS.hPut stderr
-              . overwriteNthLine (size - i)
-              . trim w
-              . blue
-              . (\b -> "[ " <> E.encodeUtf8 (T.pack lfile) <> " ] " <> b)
-              $ bs
-
-    swapRegs :: a -> Seq a -> Seq a
-    swapRegs bs = \regs -> if
-      | Sq.length regs < size -> regs |> bs
-      | otherwise             -> Sq.drop 1 regs |> bs
-
-    -- trim output line to terminal width
-    trim :: Int -> ByteString -> ByteString
-    trim w = \bs -> if
-      | BS.length bs > w && w > 5 -> BS.take (w - 4) bs <> "..."
-      | otherwise                 -> bs
-
-  -- Consecutively read from Fd in 512 chunks until we hit
-  -- newline or EOF.
-  readLine :: MonadIO m
-           => Fd          -- ^ input file descriptor
-           -> ByteString  -- ^ rest buffer (read across newline)
-           -> m (ByteString, ByteString, Bool) -- ^ (full line, rest, eof)
-  readLine fd = go
-   where
-    go inBs = do
-      -- if buffer is not empty, process it first
-      mbs <- if BS.length inBs == 0
-               -- otherwise attempt read
-               then liftIO
-                    $ handleIO (\e -> if isEOFError e then pure Nothing else ioError e)
-                    $ fmap Just
-                    $ SPIB.fdRead fd 512
-               else pure $ Just inBs
-      case mbs of
-        Nothing -> pure ("", "", True)
-        Just bs -> do
-          -- split on newline
-          let (line, rest) = BS.span (/= _lf) bs
-          if
-            | BS.length rest /= 0 -> pure (line, BS.tail rest, False)
-            -- if rest is empty, then there was no newline, process further
-            | otherwise           -> (\(l, r, b) -> (line <> l, r, b)) <$!> go mempty
-
-  readTilEOF :: MonadIO m => (ByteString -> m a) -> Fd -> m ()
-  readTilEOF ~action' fd' = go mempty
-   where
-    go bs' = do
-      (bs, rest, eof) <- readLine fd' bs'
-      if eof
-         then liftIO $ ioError (mkIOError eofErrorType "" Nothing Nothing)
-         else void (action' bs) >> go rest
-
-
--- | Capture the stdout and stderr of the given action, which
--- is run in a subprocess. Stdin is closed. You might want to
--- 'race' this to make sure it terminates.
-captureOutStreams :: IO a
-                     -- ^ the action to execute in a subprocess
-                  -> IO CapturedProcess
-captureOutStreams action = do
-  actionWithPipes $ \(parentStdoutRead, childStdoutWrite) ->
-    actionWithPipes $ \(parentStderrRead, childStderrWrite) -> do
-      pid <- SPP.forkProcess $ do
-        -- dup stdout
-        void $ dupTo childStdoutWrite stdOutput
-        closeFd childStdoutWrite
-        closeFd parentStdoutRead
-
-        -- dup stderr
-        void $ dupTo childStderrWrite stdError
-        closeFd childStderrWrite
-        closeFd parentStderrRead
-
-        -- execute the action
-        a <- action
-        void $ evaluate a
-
-      -- close everything we don't need
-      closeFd childStdoutWrite
-      closeFd childStderrWrite
-
-      -- start thread that writes the output
-      refOut <- newIORef BL.empty
-      refErr <- newIORef BL.empty
-      done   <- newEmptyMVar
-      _      <-
-        forkIO
-        $ EX.handle (\(_ :: IOException) -> pure ())
-        $ flip EX.finally (putMVar done ())
-        $ writeStds parentStdoutRead parentStderrRead refOut refErr
-
-      status <- SPP.getProcessStatus True True pid
-      void $ race (takeMVar done) (threadDelay (1000000 * 3))
-
-      case status of
-        -- readFd will take care of closing the fd
-        Just (SPP.Exited es) -> do
-          stdout' <- readIORef refOut
-          stderr' <- readIORef refErr
-          pure $ CapturedProcess { _exitCode = es
-                                 , _stdOut   = stdout'
-                                 , _stdErr   = stderr'
-                                 }
-
-        _ -> throwIO $ userError ("No such PID " ++ show pid)
-
- where
-  writeStds :: Fd -> Fd -> IORef BL.ByteString -> IORef BL.ByteString -> IO ()
-  writeStds pout perr rout rerr = do
-    doneOut <- newEmptyMVar
-    void
-      $ forkIO
-      $ hideError eofErrorType
-      $ flip EX.finally (putMVar doneOut ())
-      $ readTilEOF (\x -> modifyIORef' rout (<> BL.fromStrict x)) pout
-    doneErr <- newEmptyMVar
-    void
-      $ forkIO
-      $ hideError eofErrorType
-      $ flip EX.finally (putMVar doneErr ())
-      $ readTilEOF (\x -> modifyIORef' rerr (<> BL.fromStrict x)) perr
-    takeMVar doneOut
-    takeMVar doneErr
-
-  readTilEOF ~action' fd' = do
-    bs <- SPIB.fdRead fd' 512
-    void $ action' bs
-    readTilEOF action' fd'
-
-
-actionWithPipes :: ((Fd, Fd) -> IO b) -> IO b
-actionWithPipes a =
-  createPipe >>= \(p1, p2) -> flip finally (cleanup [p1, p2]) $ a (p1, p2)
-
-cleanup :: [Fd] -> IO ()
-cleanup fds = for_ fds $ \fd -> handleIO (\_ -> pure ()) $ closeFd fd
-
-
-
--- | Create a new regular file in write-only mode. The file must not exist.
-createRegularFileFd :: FileMode -> FilePath -> IO Fd
-createRegularFileFd fm dest =
-  openFd dest WriteOnly (Just fm) defaultFileFlags{ exclusive = True }
-
-
--- | Thin wrapper around `executeFile`.
-exec :: MonadIO m
-     => String           -- ^ thing to execute
-     -> [String]         -- ^ args for the thing
-     -> Maybe FilePath   -- ^ optionally chdir into this
-     -> Maybe [(String, String)] -- ^ optional environment
-     -> m (Either ProcessError ())
-exec exe args chdir env = liftIO $ do
-  pid <- SPP.forkProcess $ do
-    maybe (pure ()) changeWorkingDirectory chdir
-    SPP.executeFile exe (not ("./" `isPrefixOf` exe)) args env
-
-  fmap (toProcessError exe args) $ SPP.getProcessStatus True True pid
-
-
-toProcessError :: FilePath
-               -> [String]
-               -> Maybe ProcessStatus
-               -> Either ProcessError ()
-toProcessError exe args mps = case mps of
-  Just (SPP.Exited (ExitFailure xi)) -> Left $ NonZeroExit xi exe args
-  Just (SPP.Exited ExitSuccess    ) -> Right ()
-  Just (Terminated _ _             ) -> Left $ PTerminated exe args
-  Just (Stopped _                  ) -> Left $ PStopped exe args
-  Nothing                            -> Left $ NoSuchPid exe args
-
-
-
-chmod_755 :: (MonadReader env m, HasLog env, MonadIO m) => FilePath -> m ()
-chmod_755 fp = do
-  let exe_mode =
-          nullFileMode
-            `unionFileModes` ownerExecuteMode
-            `unionFileModes` ownerReadMode
-            `unionFileModes` ownerWriteMode
-            `unionFileModes` groupExecuteMode
-            `unionFileModes` groupReadMode
-            `unionFileModes` otherExecuteMode
-            `unionFileModes` otherReadMode
-  logDebug ("chmod 755 " <> T.pack fp)
-  liftIO $ setFileMode fp exe_mode
-
-
--- |Default permissions for a new file.
-newFilePerms :: FileMode
-newFilePerms =
-  ownerWriteMode
-    `unionFileModes` ownerReadMode
-    `unionFileModes` groupWriteMode
-    `unionFileModes` groupReadMode
-    `unionFileModes` otherWriteMode
-    `unionFileModes` otherReadMode
-
-
--- | Checks whether the binary is a broken link.
-isBrokenSymlink :: FilePath -> IO Bool
-isBrokenSymlink fp = do
-  try (pathIsSymbolicLink fp) >>= \case
-    Right True -> do
-      let symDir = takeDirectory fp
-      tfp <- getSymbolicLinkTarget fp
-      not <$> doesPathExist
-        -- this drops 'symDir' if 'tfp' is absolute
-        (symDir </> tfp)
-    Right b -> pure b
-    Left e | isDoesNotExistError e -> pure False
-           | otherwise -> throwIO e
diff --git a/lib/GHCup/Utils/File/Windows.hs b/lib/GHCup/Utils/File/Windows.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/File/Windows.hs
+++ /dev/null
@@ -1,271 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE FlexibleContexts  #-}
-
-{-|
-Module      : GHCup.Utils.File.Windows
-Description : File and windows APIs
-Copyright   : (c) Julian Ospald, 2020
-License     : LGPL-3.0
-Maintainer  : hasufell@hasufell.de
-Stability   : experimental
-Portability : Windows
-
-This module handles file and executable handling.
-Some of these functions use sophisticated logging.
--}
-module GHCup.Utils.File.Windows where
-
-import {-# SOURCE #-} GHCup.Utils ( getLinkTarget, pathIsLink )
-import           GHCup.Utils.Dirs
-import           GHCup.Utils.File.Common
-import           GHCup.Utils.Logger
-import           GHCup.Types
-import           GHCup.Types.Optics
-
-import           Control.Concurrent
-import           Control.DeepSeq
-import           Control.Exception.Safe
-import           Control.Monad
-import           Control.Monad.Reader
-import           Data.List
-import           Foreign.C.Error
-import           GHC.IO.Exception
-import           GHC.IO.Handle
-import           System.Directory
-import           System.Environment
-import           System.FilePath
-import           System.IO
-import           System.Process
- 
-import qualified Control.Exception             as EX
-import qualified Data.ByteString               as BS
-import qualified Data.ByteString.Lazy          as BL
-import qualified Data.Map.Strict               as Map
-import qualified Data.Text                     as T
-
-
-
-toProcessError :: FilePath
-               -> [FilePath]
-               -> ExitCode
-               -> Either ProcessError ()
-toProcessError exe args exitcode = case exitcode of
-  (ExitFailure xi) -> Left $ NonZeroExit xi exe args
-  ExitSuccess -> Right ()
-
-
--- | @readCreateProcessWithExitCode@ works exactly like 'readProcessWithExitCode' except that it
--- lets you pass 'CreateProcess' giving better flexibility.
---
--- Note that @Handle@s provided for @std_in@, @std_out@, or @std_err@ via the CreateProcess
--- record will be ignored.
---
--- @since 1.2.3.0
-readCreateProcessWithExitCodeBS
-    :: CreateProcess
-    -> BL.ByteString
-    -> IO (ExitCode, BL.ByteString, BL.ByteString) -- ^ exitcode, stdout, stderr
-readCreateProcessWithExitCodeBS cp input = do
-    let cp_opts = cp {
-                    std_in  = CreatePipe,
-                    std_out = CreatePipe,
-                    std_err = CreatePipe
-                  }
-    withCreateProcess_ "readCreateProcessWithExitCodeBS" cp_opts $
-      \mb_inh mb_outh mb_errh ph ->
-        case (mb_inh, mb_outh, mb_errh) of
-          (Just inh, Just outh, Just errh) -> do
-
-            out <- BS.hGetContents outh
-            err <- BS.hGetContents errh
-
-            -- fork off threads to start consuming stdout & stderr
-            withForkWait  (EX.evaluate $ rnf out) $ \waitOut ->
-             withForkWait (EX.evaluate $ rnf err) $ \waitErr -> do
-
-              -- now write any input
-              unless (BL.null input) $
-                ignoreSigPipe $ BL.hPut inh input
-              -- hClose performs implicit hFlush, and thus may trigger a SIGPIPE
-              ignoreSigPipe $ hClose inh
-
-              -- wait on the output
-              waitOut
-              waitErr
-
-              hClose outh
-              hClose errh
-
-            -- wait on the process
-            ex <- waitForProcess ph
-            return (ex, BL.fromStrict out, BL.fromStrict err)
-
-          (Nothing,_,_) -> error "readCreateProcessWithExitCodeBS: Failed to get a stdin handle."
-          (_,Nothing,_) -> error "readCreateProcessWithExitCodeBS: Failed to get a stdout handle."
-          (_,_,Nothing) -> error "readCreateProcessWithExitCodeBS: Failed to get a stderr handle."
- where
-  ignoreSigPipe :: IO () -> IO ()
-  ignoreSigPipe = EX.handle $ \e -> case e of
-                                     IOError { ioe_type  = ResourceVanished
-                                             , ioe_errno = Just ioe }
-                                       | Errno ioe == ePIPE -> return ()
-                                     _ -> throwIO e
-  -- wrapper so we can get exceptions with the appropriate function name.
-  withCreateProcess_
-    :: String
-    -> CreateProcess
-    -> (Maybe Handle -> Maybe Handle -> Maybe Handle -> ProcessHandle -> IO a)
-    -> IO a
-  withCreateProcess_ fun c action =
-      EX.bracketOnError (createProcess_ fun c) cleanupProcess
-                       (\(m_in, m_out, m_err, ph) -> action m_in m_out m_err ph)
-
--- | Fork a thread while doing something else, but kill it if there's an
--- exception.
---
--- This is important in the cases above because we want to kill the thread
--- that is holding the Handle lock, because when we clean up the process we
--- try to close that handle, which could otherwise deadlock.
---
-withForkWait :: IO () -> (IO () ->  IO a) -> IO a
-withForkWait async' body = do
-  waitVar <- newEmptyMVar :: IO (MVar (Either SomeException ()))
-  mask $ \restore -> do
-    tid <- forkIO $ try (restore async') >>= putMVar waitVar
-    let wait' = takeMVar waitVar >>= either throwIO return
-    restore (body wait') `EX.onException` killThread tid
-
-
--- | Execute the given command and collect the stdout, stderr and the exit code.
--- The command is run in a subprocess.
-executeOut :: MonadIO m
-           => FilePath          -- ^ command as filename, e.g. 'ls'
-           -> [String]          -- ^ arguments to the command
-           -> Maybe FilePath    -- ^ chdir to this path
-           -> m CapturedProcess
-executeOut path args chdir = do
-  cp <- createProcessWithMingwPath ((proc path args){ cwd = chdir })
-  (exit, out, err) <- liftIO $ readCreateProcessWithExitCodeBS cp ""
-  pure $ CapturedProcess exit out err
-
-
-execLogged :: ( MonadReader env m
-              , HasDirs env
-              , HasLog env
-              , HasSettings env
-              , MonadIO m
-              , MonadThrow m)
-           => FilePath         -- ^ thing to execute
-           -> [String]         -- ^ args for the thing
-           -> Maybe FilePath   -- ^ optionally chdir into this
-           -> FilePath         -- ^ log filename (opened in append mode)
-           -> Maybe [(String, String)] -- ^ optional environment
-           -> m (Either ProcessError ())
-execLogged exe args chdir lfile env = do
-  Dirs {..} <- getDirs
-  logDebug $ T.pack $ "Running " <> exe <> " with arguments " <> show args
-  let stdoutLogfile = logsDir </> lfile <> ".stdout.log"
-      stderrLogfile = logsDir </> lfile <> ".stderr.log"
-  cp <- createProcessWithMingwPath ((proc exe args)
-    { cwd = chdir
-    , env = env
-    , std_in = CreatePipe
-    , std_out = CreatePipe
-    , std_err = CreatePipe
-    })
-  fmap (toProcessError exe args)
-    $ liftIO
-    $ withCreateProcess cp
-    $ \_ mout merr ph ->
-        case (mout, merr) of
-          (Just cStdout, Just cStderr) -> do
-            withForkWait (tee stdoutLogfile cStdout) $ \waitOut ->
-              withForkWait (tee stderrLogfile cStderr) $ \waitErr -> do
-                waitOut
-                waitErr
-            waitForProcess ph
-          _ -> fail "Could not acquire out/err handle"
-
- where
-  tee :: FilePath -> Handle -> IO ()
-  tee logFile handle' = go
-    where
-      go = do
-        some <- BS.hGetSome handle' 512
-        if BS.null some
-          then pure ()
-          else do
-            void $ BS.appendFile logFile some
-            -- subprocess stdout also goes to stderr for logging
-            void $ BS.hPut stderr some
-            go
-        
-
--- | Thin wrapper around `executeFile`.
-exec :: MonadIO m
-     => FilePath       -- ^ thing to execute
-     -> [FilePath]     -- ^ args for the thing
-     -> Maybe FilePath   -- ^ optionally chdir into this
-     -> Maybe [(String, String)] -- ^ optional environment
-     -> m (Either ProcessError ())
-exec exe args chdir env = do
-  cp <- createProcessWithMingwPath ((proc exe args) { cwd = chdir, env = env })
-  exit_code <- liftIO $ withCreateProcess cp $ \_ _ _ p -> waitForProcess p
-  pure $ toProcessError exe args exit_code
-
-
--- | Thin wrapper around `executeFile`.
-execShell :: MonadIO m
-          => FilePath       -- ^ thing to execute
-          -> [FilePath]     -- ^ args for the thing
-          -> Maybe FilePath   -- ^ optionally chdir into this
-          -> Maybe [(String, String)] -- ^ optional environment
-          -> m (Either ProcessError ())
-execShell exe args chdir env = do
-  let cmd = exe <> " " <> concatMap (' ':) args
-  cp <- createProcessWithMingwPath ((shell cmd) { cwd = chdir, env = env })
-  exit_code <- liftIO $ withCreateProcess cp $ \_ _ _ p -> waitForProcess p
-  pure $ toProcessError cmd [] exit_code
-
-
-chmod_755 :: MonadIO m => FilePath -> m ()
-chmod_755 fp =
-  let perm = setOwnerWritable True emptyPermissions
-  in liftIO $ setPermissions fp perm
-
-
-createProcessWithMingwPath :: MonadIO m
-                          => CreateProcess
-                          -> m CreateProcess
-createProcessWithMingwPath cp = do
-  msys2Dir <- liftIO ghcupMsys2Dir
-  cEnv <- Map.fromList <$> maybe (liftIO getEnvironment) pure (env cp)
-  let mingWPaths = [msys2Dir </> "usr" </> "bin"
-                   ,msys2Dir </> "mingw64" </> "bin"]
-      paths = ["PATH", "Path"]
-      curPaths = (\x -> maybe [] splitSearchPath (Map.lookup x cEnv)) =<< paths
-      newPath = intercalate [searchPathSeparator] (mingWPaths ++ curPaths)
-      envWithoutPath = foldr (\x y -> Map.delete x y) cEnv paths
-      envWithNewPath = Map.insert "Path" newPath envWithoutPath
-  liftIO $ setEnv "Path" newPath
-  pure $ cp { env = Just $ Map.toList envWithNewPath }
-
-ghcupMsys2Dir :: IO FilePath
-ghcupMsys2Dir =
-  lookupEnv "GHCUP_MSYS2" >>= \case
-    Just fp -> pure fp
-    Nothing -> do
-      baseDir <- liftIO ghcupBaseDir
-      pure (baseDir </> "msys64")
-
--- | Checks whether the binary is a broken link.
-isBrokenSymlink :: FilePath -> IO Bool
-isBrokenSymlink fp = do
-  b <- pathIsLink fp
-  if b
-  then do
-    tfp <- getLinkTarget fp
-    not <$> doesPathExist
-      -- this drops 'symDir' if 'tfp' is absolute
-      (takeDirectory fp </> tfp)
-  else pure False
diff --git a/lib/GHCup/Utils/Logger.hs b/lib/GHCup/Utils/Logger.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/Logger.hs
+++ /dev/null
@@ -1,130 +0,0 @@
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE DataKinds        #-}
-{-# LANGUAGE OverloadedStrings   #-}
-
-{-|
-Module      : GHCup.Utils.Logger
-Description : logger definition
-Copyright   : (c) Julian Ospald, 2020
-License     : LGPL-3.0
-Maintainer  : hasufell@hasufell.de
-Stability   : experimental
-Portability : portable
-
-Here we define our main logger.
--}
-module GHCup.Utils.Logger where
-
-import           GHCup.Types
-import           GHCup.Types.Optics
-import {-# SOURCE #-} GHCup.Utils.File.Common (findFiles)
-import           GHCup.Utils.String.QQ
-
-import           Control.Exception.Safe
-import           Control.Monad
-import           Control.Monad.IO.Class
-import           Control.Monad.Reader
-import           Data.Text               ( Text )
-import           Optics
-import           Prelude                 hiding ( appendFile )
-import           System.Console.Pretty
-import           System.FilePath
-import           System.IO.Error
-import           Text.Regex.Posix
-
-import qualified Data.ByteString               as B
-import GHCup.Utils.Prelude
-import qualified Data.Text                     as T
-
-logInfo :: ( MonadReader env m
-           , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
-           , MonadIO m
-           )
-        => Text
-        -> m ()
-logInfo = logInternal Info
-
-logWarn :: ( MonadReader env m
-           , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
-           , MonadIO m
-           )
-        => Text
-        -> m ()
-logWarn = logInternal Warn
-
-logDebug :: ( MonadReader env m
-            , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
-            , MonadIO m
-            )
-         => Text
-         -> m ()
-logDebug = logInternal Debug
-
-logError :: ( MonadReader env m
-            , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
-            , MonadIO m
-            )
-         => Text
-         -> m ()
-logError = logInternal Error
-
-
-logInternal :: ( MonadReader env m
-               , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
-               , MonadIO m
-               ) => LogLevel
-                 -> Text
-                 -> m ()
-logInternal logLevel msg = do
-  LoggerConfig {..} <- gets @"loggerConfig"
-  let color' c = if fancyColors then color c else id
-  let style' = case logLevel of
-        Debug   -> style Bold . color' Blue
-        Info    -> style Bold . color' Green
-        Warn    -> style Bold . color' Yellow
-        Error   -> style Bold . color' Red
-  let l = case logLevel of
-        Debug   -> style' "[ Debug ]"
-        Info    -> style' "[ Info  ]"
-        Warn    -> style' "[ Warn  ]"
-        Error   -> style' "[ Error ]"
-  let strs = T.split (== '\n') msg
-  let out = case strs of
-              [] -> T.empty
-              (x:xs) -> 
-                  foldr (\a b -> a <> "\n" <> b) mempty
-                . ((l <> " " <> x) :)
-                . fmap (\line' -> style' "[ ...   ] " <> line' )
-                $ xs
-
-  when (lcPrintDebug || (not lcPrintDebug && (logLevel /= Debug)))
-    $ liftIO $ consoleOutter out
-
-  -- raw output
-  let lr = case logLevel of
-        Debug   -> "Debug:"
-        Info    -> "Info:"
-        Warn    -> "Warn:"
-        Error   -> "Error:"
-  let outr = lr <> " " <> msg <> "\n"
-  liftIO $ fileOutter outr
-
-
-initGHCupFileLogging :: ( MonadReader env m
-                        , HasDirs env
-                        , MonadIO m
-                        , MonadMask m
-                        ) => m FilePath
-initGHCupFileLogging = do
-  Dirs { logsDir } <- getDirs
-  let logfile = logsDir </> "ghcup.log"
-  logFiles <- liftIO $ findFiles
-    logsDir
-    (makeRegexOpts compExtended
-                   execBlank
-                   ([s|^.*\.log$|] :: B.ByteString)
-    )
-  forM_ logFiles $ hideError doesNotExistErrorType . recycleFile . (logsDir </>)
-
-  liftIO $ writeFile logfile ""
-  pure logfile
diff --git a/lib/GHCup/Utils/Logger.hs-boot b/lib/GHCup/Utils/Logger.hs-boot
deleted file mode 100644
--- a/lib/GHCup/Utils/Logger.hs-boot
+++ /dev/null
@@ -1,19 +0,0 @@
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE DataKinds        #-}
-
-module GHCup.Utils.Logger where
-
-import           GHCup.Types
-
-import           Control.Monad.IO.Class
-import           Control.Monad.Reader
-import           Data.Text               ( Text )
-import           Optics
-
-logWarn :: ( MonadReader env m
-           , LabelOptic' "loggerConfig" A_Lens env LoggerConfig
-           , MonadIO m
-           )
-        => Text
-        -> m ()
-
diff --git a/lib/GHCup/Utils/MegaParsec.hs b/lib/GHCup/Utils/MegaParsec.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/MegaParsec.hs
+++ /dev/null
@@ -1,124 +0,0 @@
-{-# LANGUAGE CPP                  #-}
-{-# LANGUAGE OverloadedStrings    #-}
-
-{-|
-Module      : GHCup.Utils.MegaParsec
-Description : MegaParsec utilities
-Copyright   : (c) Julian Ospald, 2020
-License     : LGPL-3.0
-Maintainer  : hasufell@hasufell.de
-Stability   : experimental
-Portability : portable
--}
-module GHCup.Utils.MegaParsec where
-
-import           GHCup.Types
-
-import           Control.Applicative
-#if !MIN_VERSION_base(4,13,0)
-import           Control.Monad.Fail             ( MonadFail )
-#endif
-import           Data.Functor
-import           Data.Maybe
-import           Data.Text                      ( Text )
-import           Data.Versions
-import           Data.Void
-import           System.FilePath
-
-import qualified Data.List.NonEmpty            as NE
-import qualified Data.Text                     as T
-import qualified Text.Megaparsec               as MP
-
-
-choice' :: (MonadFail f, MP.MonadParsec e s f) => [f a] -> f a
-choice' []       = fail "Empty list"
-choice' [x     ] = x
-choice' (x : xs) = MP.try x <|> choice' xs
-
-
-parseUntil :: MP.Parsec Void Text a -> MP.Parsec Void Text Text
-parseUntil p = do
-  (MP.try (MP.lookAhead p) $> mempty)
-    <|> (do
-          c  <- T.singleton <$> MP.anySingle
-          c2 <- parseUntil p
-          pure (c `mappend` c2)
-        )
-
-parseUntil1 :: MP.Parsec Void Text a -> MP.Parsec Void Text Text
-parseUntil1 p = do
-  i1 <- MP.getOffset
-  t <- parseUntil p
-  i2 <- MP.getOffset
-  if i1 == i2 then fail "empty parse" else pure t
-
-
-
--- | Parses e.g.
---   * armv7-unknown-linux-gnueabihf-ghc
---   * armv7-unknown-linux-gnueabihf-ghci
-ghcTargetBinP :: Text -> MP.Parsec Void Text (Maybe Text, Text)
-ghcTargetBinP t =
-  (,)
-    <$> (   MP.try
-            (Just <$> parseUntil1 (MP.chunk "-" *> MP.chunk t) <* MP.chunk "-"
-            )
-        <|> ((\ _ x -> x) Nothing <$> mempty)
-        )
-    <*> (MP.chunk t <* MP.eof)
-
-
--- | Extracts the version from @ProjectVersion="8.10.5"@.
-ghcProjectVersion :: MP.Parsec Void Text Version
-ghcProjectVersion = do
-  _ <- MP.chunk "ProjectVersion=\""
-  ver <- parseUntil1 $ MP.chunk "\""
-  MP.setInput ver
-  version'
-
-
--- | Extracts target triple and version from e.g.
---   * armv7-unknown-linux-gnueabihf-8.8.3
---   * armv7-unknown-linux-gnueabihf-8.8.3
-ghcTargetVerP :: MP.Parsec Void Text GHCTargetVersion
-ghcTargetVerP =
-  (\x y -> GHCTargetVersion x y)
-    <$> (MP.try (Just <$> parseUntil1 (MP.chunk "-" *> verP') <* MP.chunk "-")
-        <|> ((\ _ x -> x) Nothing <$> mempty)
-        )
-    <*> (version' <* MP.eof)
- where
-  verP' :: MP.Parsec Void Text Text
-  verP' = do
-    v <- version'
-    let startsWithDigists =
-          and
-            . take 3
-            . concatMap
-              (map
-                (\case
-                  (Digits _) -> True
-                  (Str    _) -> False
-                ) . NE.toList)
-            . NE.toList
-            $ _vChunks v
-    if startsWithDigists && isNothing (_vEpoch v)
-      then pure $ prettyVer v
-      else fail "Oh"
-
-
-verP :: MP.Parsec Void Text Text -> MP.Parsec Void Text Versioning
-verP suffix = do
-  ver <- parseUntil suffix
-  if T.null ver
-    then fail "empty version"
-    else do
-      rest <- MP.getInput
-      MP.setInput ver
-      v <- versioning'
-      MP.setInput rest
-      pure v
-
-
-pathSep :: MP.Parsec Void Text Char
-pathSep = MP.oneOf pathSeparators
diff --git a/lib/GHCup/Utils/Posix.hs b/lib/GHCup/Utils/Posix.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/Posix.hs
+++ /dev/null
@@ -1,14 +0,0 @@
-module GHCup.Utils.Posix where
-
-
--- | Enables ANSI support on windows, does nothing on unix.
---
--- Returns 'Left str' on errors and 'Right bool' on success, where
--- 'bool' markes whether ansi support was already enabled.
---
--- This function never crashes.
---
--- Rip-off of https://docs.rs/ansi_term/0.12.1/x86_64-pc-windows-msvc/src/ansi_term/windows.rs.html#10-61
-enableAnsiSupport :: IO (Either String Bool)
-enableAnsiSupport = pure (Right True)
-
diff --git a/lib/GHCup/Utils/Prelude.hs b/lib/GHCup/Utils/Prelude.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/Prelude.hs
+++ /dev/null
@@ -1,765 +0,0 @@
-{-# LANGUAGE CPP                 #-}
-{-# LANGUAGE DataKinds           #-}
-{-# LANGUAGE FlexibleContexts    #-}
-{-# LANGUAGE FlexibleInstances   #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeFamilies        #-}
-{-# LANGUAGE TypeOperators       #-}
-
-{-|
-Module      : GHCup.Utils.Prelude
-Description : MegaParsec utilities
-Copyright   : (c) Julian Ospald, 2020
-License     : LGPL-3.0
-Maintainer  : hasufell@hasufell.de
-Stability   : experimental
-Portability : portable
-
-GHCup specific prelude. Lots of Excepts functionality.
--}
-module GHCup.Utils.Prelude
-  (module GHCup.Utils.Prelude,
-#if defined(IS_WINDOWS)
-   module GHCup.Utils.Prelude.Windows
-#else
-   module GHCup.Utils.Prelude.Posix
-#endif
-  )
-where
-
-import           GHCup.Types
-import           GHCup.Errors
-import           GHCup.Types.Optics
-import {-# SOURCE #-} GHCup.Utils.Logger (logWarn)
-#if defined(IS_WINDOWS)
-import           GHCup.Utils.Prelude.Windows
-#else
-import           GHCup.Utils.Prelude.Posix
-#endif
-
-import           Control.Applicative
-import           Control.Exception.Safe
-import           Control.Monad
-import           Control.Monad.IO.Class
-import           Control.Monad.Reader
-import           Data.Bifunctor
-import           Data.ByteString                ( ByteString )
-import           Data.List                      ( nub, intercalate, stripPrefix, isPrefixOf, dropWhileEnd, intersperse )
-import           Data.Maybe
-import           Data.Foldable
-import           Data.List.NonEmpty             ( NonEmpty( (:|) ))
-import           Data.String
-import           Data.Text                      ( Text )
-import           Data.Versions
-import           Data.Word8                  hiding ( isDigit )
-import           Haskus.Utils.Types.List
-import           Haskus.Utils.Variant.Excepts
-import           Text.PrettyPrint.HughesPJClass ( prettyShow, Pretty )
-import           System.IO.Error
-import           System.IO.Temp
-import           System.IO.Unsafe
-import           System.Directory
-import           System.FilePath
-
-import           Control.Retry
-import           GHC.IO.Exception
-
-import qualified Data.ByteString               as B
-import qualified Data.ByteString.Lazy          as L
-import qualified Data.Strict.Maybe             as S
-import qualified Data.List.Split               as Split
-import qualified Data.List.NonEmpty            as NE
-import qualified Data.Text                     as T
-import qualified Data.Text.Encoding            as E
-import qualified Data.Text.Encoding.Error      as E
-import qualified Data.Text.Lazy                as TL
-import qualified Data.Text.Lazy.Builder        as B
-import qualified Data.Text.Lazy.Builder.Int    as B
-import qualified Data.Text.Lazy.Encoding       as TLE
-
-
--- $setup
--- >>> import Data.ByteString.Internal (c2w, w2c)
--- >>> import Test.QuickCheck
--- >>> import Data.Word8
--- >>> import qualified Data.Text as T
--- >>> import qualified Data.Char as C
--- >>> import Data.List
--- >>> instance Arbitrary T.Text where arbitrary = T.pack <$> arbitrary
-
-
-fS :: IsString a => String -> a
-fS = fromString
-
-fromStrictMaybe :: S.Maybe a -> Maybe a
-fromStrictMaybe = S.maybe Nothing Just
-
-fSM :: S.Maybe a -> Maybe a
-fSM = fromStrictMaybe
-
-toStrictMaybe :: Maybe a -> S.Maybe a
-toStrictMaybe = maybe S.Nothing S.Just
-
-tSM :: Maybe a -> S.Maybe a
-tSM = toStrictMaybe
-
-internalError :: String -> IO a
-internalError = fail . ("Internal error: " <>)
-
-iE :: String -> IO a
-iE = internalError
-
-
-showT :: Show a => a -> Text
-showT = fS . show
-
--- | Like 'when', but where the test can be monadic.
-whenM :: Monad m => m Bool -> m () -> m ()
-whenM ~b ~t = ifM b t (return ())
-
--- | Like 'unless', but where the test can be monadic.
-unlessM :: Monad m => m Bool -> m () -> m ()
-unlessM ~b ~f = ifM b (return ()) f
-
--- | Like @if@, but where the test can be monadic.
-ifM :: Monad m => m Bool -> m a -> m a -> m a
-ifM ~b ~t ~f = do
-  b' <- b
-  if b' then t else f
-
-whileM :: Monad m => m a -> (a -> m Bool) -> m a
-whileM ~action ~f = do
-  a  <- action
-  b' <- f a
-  if b' then whileM action f else pure a
-
-whileM_ :: Monad m => m a -> (a -> m Bool) -> m ()
-whileM_ ~action = void . whileM action
-
-guardM :: (Monad m, Alternative m) => m Bool -> m ()
-guardM ~f = guard =<< f
-
-
-handleIO' :: (MonadIO m, MonadCatch m)
-          => IOErrorType
-          -> (IOException -> m a)
-          -> m a
-          -> m a
-handleIO' err handler = handleIO
-  (\e -> if err == ioeGetErrorType e then handler e else liftIO $ ioError e)
-
-
-(??) :: forall e es a m . (Monad m, e :< es) => Maybe a -> e -> Excepts es m a
-(??) m e = maybe (throwE e) pure m
-
-
-(!?) :: forall e es a m
-      . (Monad m, e :< es)
-     => m (Maybe a)
-     -> e
-     -> Excepts es m a
-(!?) em e = lift em >>= (?? e)
-
-
-lE :: forall e es a m . (Monad m, e :< es) => Either e a -> Excepts es m a
-lE = liftE . veitherToExcepts . fromEither
-
-lE' :: forall e' e es a m
-     . (Monad m, e :< es)
-    => (e' -> e)
-    -> Either e' a
-    -> Excepts es m a
-lE' f = liftE . veitherToExcepts . fromEither . first f
-
-lEM :: forall e es a m . (Monad m, e :< es) => m (Either e a) -> Excepts es m a
-lEM em = lift em >>= lE
-
-lEM' :: forall e' e es a m
-      . (Monad m, e :< es)
-     => (e' -> e)
-     -> m (Either e' a)
-     -> Excepts es m a
-lEM' f em = lift em >>= lE . first f
-
--- for some obscure reason... this won't type-check if we move it to a different module
-catchWarn :: forall es m env . ( Pretty (V es)
-                             , MonadReader env m
-                             , HasLog env
-                             , MonadIO m
-                             , Monad m) => Excepts es m () -> Excepts '[] m ()
-catchWarn = catchAllE @_ @es (\v -> lift $ logWarn (T.pack . prettyShow $ v))
-
-fromEither :: Either a b -> VEither '[a] b
-fromEither = either (VLeft . V) VRight
-
-
-liftIOException' :: ( MonadCatch m
-                    , MonadIO m
-                    , Monad m
-                    , e :< es'
-                    , LiftVariant es es'
-                    )
-                 => IOErrorType
-                 -> e
-                 -> Excepts es m a
-                 -> Excepts es' m a
-liftIOException' errType ex =
-  handleIO
-      (\e ->
-        if errType == ioeGetErrorType e then throwE ex else liftIO $ ioError e
-      )
-    . liftE
-
-
-liftIOException :: (MonadCatch m, MonadIO m, Monad m, e :< es')
-                => IOErrorType
-                -> e
-                -> m a
-                -> Excepts es' m a
-liftIOException errType ex =
-  handleIO
-      (\e ->
-        if errType == ioeGetErrorType e then throwE ex else liftIO $ ioError e
-      )
-    . lift
-
-
--- | Uses safe-exceptions.
-hideError :: (MonadIO m, MonadCatch m) => IOErrorType -> m () -> m ()
-hideError err = handleIO (\e -> if err == ioeGetErrorType e then pure () else liftIO . ioError $ e)
-
-
-hideErrorDef :: (MonadIO m, MonadCatch m) => [IOErrorType] -> a -> m a -> m a
-hideErrorDef errs def =
-  handleIO (\e -> if ioeGetErrorType e `elem` errs then pure def else liftIO $ ioError e)
-
-
-hideErrorDefM :: (MonadIO m, MonadCatch m) => [IOErrorType] -> m a -> m a -> m a
-hideErrorDefM errs def =
-  handleIO (\e -> if ioeGetErrorType e `elem` errs then def else liftIO $ ioError e)
-
-
--- TODO: does this work?
-hideExcept :: forall e es es' a m
-            . (Monad m, e :< es, LiftVariant (Remove e es) es')
-           => e
-           -> a
-           -> Excepts es m a
-           -> Excepts es' m a
-hideExcept _ a =
-  catchLiftLeft ((\_ -> pure a) :: (e -> Excepts es' m a))
-
-
-hideExcept' :: forall e es es' m
-             . (Monad m, e :< es, LiftVariant (Remove e es) es')
-            => e
-            -> Excepts es m ()
-            -> Excepts es' m ()
-hideExcept' _ =
-  catchLiftLeft ((\_ -> pure ()) :: (e -> Excepts es' m ()))
-
-
-reThrowAll :: forall e es es' a m
-            . (Monad m, e :< es')
-           => (V es -> e)
-           -> Excepts es m a
-           -> Excepts es' m a
-reThrowAll f = catchAllE (throwE . f)
-
-
-reThrowAllIO :: forall e es es' a m
-              . (MonadCatch m, Monad m, MonadIO m, e :< es')
-             => (V es -> e)
-             -> (IOException -> e)
-             -> Excepts es m a
-             -> Excepts es' m a
-reThrowAllIO f g = handleIO (throwE . g) . catchAllE (throwE . f)
-
-
-throwEither :: (Exception a, MonadThrow m) => Either a b -> m b
-throwEither a = case a of
-  Left  e -> throwM e
-  Right r -> pure r
-
-
-throwEither' :: (Exception a, MonadThrow m) => a -> Either x b -> m b
-throwEither' e eth = case eth of
-  Left  _ -> throwM e
-  Right r -> pure r
-
-throwMaybe :: (Exception a, MonadThrow m) => a -> Maybe b -> m b
-throwMaybe a m = case m of
-  Nothing -> throwM a
-  Just r -> pure r
-
-throwMaybeM :: (Exception a, MonadThrow m) => a -> m (Maybe b) -> m b
-throwMaybeM a am = do
-  m <- am
-  throwMaybe a m
-
-
-verToBS :: Version -> ByteString
-verToBS = E.encodeUtf8 . prettyVer
-
-verToS :: Version -> String
-verToS = T.unpack . prettyVer
-
-intToText :: Integral a => a -> T.Text
-intToText = TL.toStrict . B.toLazyText . B.decimal
-
-
-pvpToVersion :: MonadThrow m => PVP -> Text -> m Version
-pvpToVersion pvp_ rest =
-  either (\_ -> throwM $ ParseError "Couldn't convert PVP to Version") pure . version . (<> rest) . prettyPVP $ pvp_
-
--- | Convert a version to a PVP and unparsable rest.
---
--- -- prop> \v -> let (Just (pvp', r)) = versionToPVP v in pvpToVersion pvp' r === Just v
-versionToPVP :: MonadThrow m => Version -> m (PVP, Text)
-versionToPVP (Version (Just _) _ _ _) = throwM $ ParseError "Unexpected epoch"
-versionToPVP v = either (\_ -> (, rest v) <$> alternative v) (pure . (, mempty)) . pvp . prettyVer $ v
- where
-  alternative :: MonadThrow m => Version -> m PVP
-  alternative v' = case NE.takeWhile isDigit (_vChunks v') of
-    [] -> throwM $ ParseError "Couldn't convert Version to PVP"
-    xs -> pure $ pvpFromList (unsafeDigit <$> xs)
-
-  rest :: Version -> Text
-  rest (Version _ cs pr me) =
-    let chunks = NE.dropWhile isDigit cs
-        ver = intersperse (T.pack ".") . chunksAsT $ chunks
-        me' = maybe [] (\m -> [T.pack "+",m]) me
-        pr' = foldable [] (T.pack "-" :) $ intersperse (T.pack ".") (chunksAsT pr)
-        prefix = case (ver, pr', me') of
-                   (_:_, _, _) -> T.pack "."
-                   _           -> T.pack ""
-    in prefix <> mconcat (ver <> pr' <> me')
-   where
-    chunksAsT :: Functor t => t VChunk -> t Text
-    chunksAsT = fmap (foldMap f)
-      where
-        f :: VUnit -> Text
-        f (Digits i) = T.pack $ show i
-        f (Str s)    = s
-
-    foldable :: Foldable f => f b -> (f a -> f b) -> f a -> f b
-    foldable d g f | null f    = d
-                   | otherwise = g f
-
-
-
-  isDigit :: VChunk -> Bool
-  isDigit (Digits _ :| []) = True
-  isDigit _                = False
-
-  unsafeDigit :: VChunk -> Int
-  unsafeDigit (Digits x :| []) = fromIntegral x
-  unsafeDigit _ = error "unsafeDigit: wrong input"
-
-pvpFromList :: [Int] -> PVP
-pvpFromList = PVP . NE.fromList . fmap fromIntegral
-
--- | Safe 'decodeUtf8With'. Replaces an invalid input byte with
--- the Unicode replacement character U+FFFD.
-decUTF8Safe :: ByteString -> Text
-decUTF8Safe = E.decodeUtf8With E.lenientDecode
-
-decUTF8Safe' :: L.ByteString -> Text
-decUTF8Safe' = TL.toStrict . TLE.decodeUtf8With E.lenientDecode
-
-
--- | Escape a version for use in regex
-escapeVerRex :: Version -> ByteString
-escapeVerRex = B.pack . go . B.unpack . verToBS
- where
-  go [] = []
-  go (x : xs) | x == _period = [_backslash, _period] ++ go xs
-              | otherwise    = x : go xs
-
--- | More permissive version of 'createDirRecursive'. This doesn't
--- error when the destination is a symlink to a directory.
-createDirRecursive' :: FilePath -> IO ()
-createDirRecursive' p =
-  handleIO (\e -> if isAlreadyExistsError e then isSymlinkDir e else throwIO e)
-    . createDirectoryIfMissing True
-    $ p
-
- where
-  isSymlinkDir e = do
-    ft <- pathIsSymbolicLink p
-    case ft of
-      True -> do
-        rp <- canonicalizePath p
-        rft <- doesDirectoryExist rp
-        case rft of
-          True -> pure ()
-          _ -> throwIO e
-      _ -> throwIO e
-
-
--- | Recursively copy the contents of one directory to another path.
---
--- This is a rip-off of Cabal library.
-copyDirectoryRecursive :: FilePath -> FilePath -> (FilePath -> FilePath -> IO ()) -> IO ()
-copyDirectoryRecursive srcDir destDir doCopy = do
-  srcFiles <- getDirectoryContentsRecursive srcDir
-  copyFilesWith destDir [ (srcDir, f)
-                          | f <- srcFiles ]
-  where
-    -- | Common implementation of 'copyFiles', 'installOrdinaryFiles',
-    -- 'installExecutableFiles' and 'installMaybeExecutableFiles'.
-    copyFilesWith :: FilePath -> [(FilePath, FilePath)] -> IO ()
-    copyFilesWith targetDir srcFiles = do
-
-      -- Create parent directories for everything
-      let dirs = map (targetDir </>) . nub . map (takeDirectory . snd) $ srcFiles
-      traverse_ (createDirectoryIfMissing True) dirs
-
-      -- Copy all the files
-      sequence_ [ let src  = srcBase   </> srcFile
-                      dest = targetDir </> srcFile
-                   in doCopy src dest
-                | (srcBase, srcFile) <- srcFiles ]
-
-
--- | List all the files in a directory and all subdirectories.
---
--- The order places files in sub-directories after all the files in their
--- parent directories. The list is generated lazily so is not well defined if
--- the source directory structure changes before the list is used.
---
-getDirectoryContentsRecursive :: FilePath -> IO [FilePath]
-getDirectoryContentsRecursive topdir = recurseDirectories [""]
-  where
-    recurseDirectories :: [FilePath] -> IO [FilePath]
-    recurseDirectories []         = return []
-    recurseDirectories (dir:dirs) = unsafeInterleaveIO $ do
-      (files, dirs') <- collect [] [] =<< getDirectoryContents (topdir </> dir)
-      files' <- recurseDirectories (dirs' ++ dirs)
-      return (files ++ files')
-
-      where
-        collect files dirs' []              = return (reverse files
-                                                     ,reverse dirs')
-        collect files dirs' (entry:entries) | ignore entry
-                                            = collect files dirs' entries
-        collect files dirs' (entry:entries) = do
-          let dirEntry = dir </> entry
-          isDirectory <- doesDirectoryExist (topdir </> dirEntry)
-          if isDirectory
-            then collect files (dirEntry:dirs') entries
-            else collect (dirEntry:files) dirs' entries
-
-        ignore ['.']      = True
-        ignore ['.', '.'] = True
-        ignore _          = False
-
-
--- https://github.com/haskell/directory/issues/110
--- https://github.com/haskell/directory/issues/96
--- https://www.sqlite.org/src/info/89f1848d7f
-recyclePathForcibly :: ( MonadIO m
-                       , MonadReader env m
-                       , HasDirs env
-                       , MonadMask m
-                       )
-                    => FilePath
-                    -> m ()
-recyclePathForcibly fp
-  | isWindows = do
-      Dirs { recycleDir } <- getDirs
-      tmp <- liftIO $ createTempDirectory recycleDir "recyclePathForcibly"
-      let dest = tmp </> takeFileName fp
-      liftIO (moveFile fp dest)
-          `catch`
-          (\e -> if | isDoesNotExistError e -> pure ()
-                    | isPermissionError e || ioeGetErrorType e == UnsupportedOperation {- EXDEV on windows -} -> recover (liftIO $ removePathForcibly fp)
-                    | otherwise -> throwIO e)
-          `finally`
-            liftIO (handleIO (\_ -> pure ()) $ removePathForcibly tmp)
-  | otherwise = liftIO $ removePathForcibly fp
-
-
-rmPathForcibly :: ( MonadIO m
-                  , MonadMask m
-                  )
-               => FilePath
-               -> m ()
-rmPathForcibly fp
-  | isWindows = recover (liftIO $ removePathForcibly fp)
-  | otherwise = liftIO $ removePathForcibly fp
-
-
-rmDirectory :: (MonadIO m, MonadMask m)
-            => FilePath
-            -> m ()
-rmDirectory fp
-  | isWindows = recover (liftIO $ removeDirectory fp)
-  | otherwise = liftIO $ removeDirectory fp
-
-
--- https://www.sqlite.org/src/info/89f1848d7f
--- https://github.com/haskell/directory/issues/96
-recycleFile :: ( MonadIO m
-               , MonadMask m
-               , MonadReader env m
-               , HasDirs env
-               )
-            => FilePath
-            -> m ()
-recycleFile fp
-  | isWindows = do
-      Dirs { recycleDir } <- getDirs
-      liftIO $ whenM (doesDirectoryExist fp) $ ioError (IOError Nothing InappropriateType "recycleFile" "" Nothing (Just fp))
-      tmp <- liftIO $ createTempDirectory recycleDir "recycleFile"
-      let dest = tmp </> takeFileName fp
-      liftIO (moveFile fp dest)
-        `catch`
-          (\e -> if isPermissionError e || ioeGetErrorType e == UnsupportedOperation {- EXDEV on windows -} then recover (liftIO $ removePathForcibly fp) else throwIO e)
-        `finally`
-          liftIO (handleIO (\_ -> pure ()) $ removePathForcibly tmp)
-  | otherwise = liftIO $ removeFile fp
-
-
-rmFile :: ( MonadIO m
-          , MonadMask m
-          )
-      => FilePath
-      -> m ()
-rmFile fp
-  | isWindows = recover (liftIO $ removeFile fp)
-  | otherwise = liftIO $ removeFile fp
-
-
-rmDirectoryLink :: (MonadIO m, MonadMask m, MonadReader env m, HasDirs env)
-                => FilePath
-                -> m ()
-rmDirectoryLink fp
-  | isWindows = recover (liftIO $ removeDirectoryLink fp)
-  | otherwise = liftIO $ removeDirectoryLink fp
-
-
-recover :: (MonadIO m, MonadMask m) => m a -> m a
-recover action = 
-  recovering (fullJitterBackoff 25000 <> limitRetries 10)
-    [\_ -> Handler (\e -> pure $ isPermissionError e)
-    ,\_ -> Handler (\e -> pure (ioeGetErrorType e == InappropriateType))
-    ,\_ -> Handler (\e -> pure (ioeGetErrorType e == UnsatisfiedConstraints))
-    ]
-    (\_ -> action)
-
-
-copyFileE :: (CopyError :< xs, MonadCatch m, MonadIO m) => FilePath -> FilePath -> Excepts xs m ()
-copyFileE from = handleIO (throwE . CopyError . show) . liftIO . copyFile from
-
-
--- | Gathering monoidal values
---
--- >>> traverseFold (pure . (:["0"])) ["1","2"]
--- ["1","0","2","0"]
--- >>> traverseFold Just ["1","2","3","4","5"]
--- Just "12345"
---
--- prop> \t -> traverseFold Just t === Just (mconcat t)
-traverseFold :: (Foldable t, Applicative m, Monoid b) => (a -> m b) -> t a -> m b
-traverseFold f = foldl (\mb a -> (<>) <$> mb <*> f a) (pure mempty)
-
--- | Gathering monoidal values
-forFold :: (Foldable t, Applicative m, Monoid b) => t a -> (a -> m b) -> m b
-forFold = \t -> (`traverseFold` t)
-
-
--- | Strip @\\r@ and @\\n@ from 'String's
---
--- >>> stripNewline "foo\n\n\n"
--- "foo"
--- >>> stripNewline "foo\n\n\nfoo"
--- "foofoo"
--- >>> stripNewline "foo\r"
--- "foo"
--- >>> stripNewline "foo"
--- "foo"
---
--- prop> \t -> stripNewline (t <> "\n") === stripNewline t
--- prop> \t -> not (any (isNewLine . c2w) t) ==> stripNewline t == t
-stripNewline :: String -> String
-stripNewline = filter (`notElem` "\n\r")
-
-
--- | Strip @\\r@ and @\\n@ from end of 'String'.
---
--- >>> stripNewlineEnd "foo\n\n\n"
--- "foo"
--- >>> stripNewlineEnd "foo\n\n\nfoo"
--- "foo\n\n\nfoo"
--- >>> stripNewlineEnd "foo\r"
--- "foo"
--- >>> stripNewlineEnd "foo"
--- "foo"
---
--- prop> \t -> stripNewlineEnd (t <> "\n") === stripNewlineEnd t
--- prop> \t -> not (any (isNewLine . c2w) t) ==> stripNewlineEnd t == t
-stripNewlineEnd :: String -> String
-stripNewlineEnd = dropWhileEnd (`elem` "\n\r")
-
-
--- | Strip @\\r@ and @\\n@ from 'Text's
---
--- >>> stripNewline' "foo\n\n\n"
--- "foo"
--- >>> stripNewline' "foo\n\n\nfoo"
--- "foofoo"
--- >>> stripNewline' "foo\r"
--- "foo"
--- >>> stripNewline' "foo"
--- "foo"
---
--- prop> \t -> stripNewline' (t <> "\n") === stripNewline' t
--- prop> \t -> not (T.any (isNewLine . c2w) t) ==> stripNewline' t == t
-stripNewline' :: T.Text -> T.Text
-stripNewline' = T.filter (`notElem` "\n\r")
-
-
--- | Is the word8 a newline?
---
--- >>> isNewLine (c2w '\n')
--- True
--- >>> isNewLine (c2w '\r')
--- True
---
--- prop> \w -> w /= _lf && w /= _cr ==> not (isNewLine w)
-isNewLine :: Word8 -> Bool
-isNewLine w
-  | w == _lf = True
-  | w == _cr = True
-  | otherwise = False
-
-
--- | Split on a PVP suffix.
---
--- >>> splitOnPVP "-" "ghc-iserv-dyn-9.3.20210706"
--- ("ghc-iserv-dyn","9.3.20210706")
--- >>> splitOnPVP "-" "ghc-iserv-dyn"
--- ("ghc-iserv-dyn","")
-splitOnPVP :: String -> String -> (String, String)
-splitOnPVP c s = case Split.splitOn c s of
-  []  -> def
-  [_] -> def
-  xs
-    | let l = last xs
-    , (Right _) <- pvp (T.pack l) -> (intercalate c (init xs), l)
-    | otherwise -> def
- where
-  def = (s, "")
-
-
-
--- | Like 'find', but where the test can be monadic.
---
--- >>> findM (Just . C.isUpper) "teST"
--- Just (Just 'S')
--- >>> findM (Just . C.isUpper) "test"
--- Just Nothing
--- >>> findM (Just . const True) ["x",undefined]
--- Just (Just "x")
-findM :: Monad m => (a -> m Bool) -> [a] -> m (Maybe a)
-findM ~p = foldr (\x -> ifM (p x) (pure $ Just x)) (pure Nothing)
-
-
--- | Drops the given suffix from a list.
---   It returns the original sequence if the sequence doesn't end with the given suffix.
---
--- >>> dropSuffix "!" "Hello World!"
--- "Hello World"
--- >>> dropSuffix "!" "Hello World!!"
--- "Hello World!"
--- >>> dropSuffix "!" "Hello World."
--- "Hello World."
-dropSuffix :: Eq a => [a] -> [a] -> [a]
-dropSuffix a b = fromMaybe b $ stripSuffix a b
-
--- | Return the prefix of the second list if its suffix
---   matches the entire first list.
---
--- >>> stripSuffix "bar" "foobar"
--- Just "foo"
--- >>> stripSuffix ""    "baz"
--- Just "baz"
--- >>> stripSuffix "foo" "quux"
--- Nothing
-stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]
-stripSuffix a b = reverse <$> stripPrefix (reverse a) (reverse b)
-
-
--- | Drops the given prefix from a list.
---   It returns the original sequence if the sequence doesn't start with the given prefix.
---
--- >>> dropPrefix "Mr. " "Mr. Men"
--- "Men"
--- >>> dropPrefix "Mr. " "Dr. Men"
--- "Dr. Men"
-dropPrefix :: Eq a => [a] -> [a] -> [a]
-dropPrefix a b = fromMaybe b $ stripPrefix a b
-
-
-
--- | Break a list into pieces separated by the first
--- list argument, consuming the delimiter. An empty delimiter is
--- invalid, and will cause an error to be raised.
---
--- >>> splitOn "\r\n" "a\r\nb\r\nd\r\ne"
--- ["a","b","d","e"]
--- >>> splitOn "aaa"  "aaaXaaaXaaaXaaa"
--- ["","X","X","X",""]
--- >>> splitOn "x"    "x"
--- ["",""]
--- >>> splitOn "x"    ""
--- [""]
---
--- prop> \s x -> s /= "" ==> intercalate s (splitOn s x) == x
--- prop> \c x -> splitOn [c] x                           == split (==c) x
-splitOn :: Eq a => [a] -> [a] -> [[a]]
-splitOn [] _ = error "splitOn, needle may not be empty"
-splitOn _ [] = [[]]
-splitOn needle haystack = a : if null b then [] else splitOn needle $ drop (length needle) b
-    where (a,b) = breakOn needle haystack
-
-
--- | Splits a list into components delimited by separators,
--- where the predicate returns True for a separator element.  The
--- resulting components do not contain the separators.  Two adjacent
--- separators result in an empty component in the output.
---
--- >>> split (== 'a') "aabbaca"
--- ["","","bb","c",""]
--- >>> split (== 'a') ""
--- [""]
--- >>> split (== ':') "::xyz:abc::123::"
--- ["","","xyz","abc","","123","",""]
--- >>> split (== ',') "my,list,here"
--- ["my","list","here"]
-split :: (a -> Bool) -> [a] -> [[a]]
-split _ [] = [[]]
-split f (x:xs)
-  | f x = [] : split f xs
-  | y:ys <- split f xs = (x:y) : ys
-  | otherwise = [[]]
-
-
--- | Find the first instance of @needle@ in @haystack@.
--- The first element of the returned tuple
--- is the prefix of @haystack@ before @needle@ is matched.  The second
--- is the remainder of @haystack@, starting with the match.
--- If you want the remainder /without/ the match, use 'stripInfix'.
---
--- >>> breakOn "::" "a::b::c"
--- ("a","::b::c")
--- >>> breakOn "/" "foobar"
--- ("foobar","")
---
--- prop> \needle haystack -> let (prefix,match) = breakOn needle haystack in prefix ++ match == haystack
-breakOn :: Eq a => [a] -> [a] -> ([a], [a])
-breakOn needle haystack | needle `isPrefixOf` haystack = ([], haystack)
-breakOn _ [] = ([], [])
-breakOn needle (x:xs) = first (x:) $ breakOn needle xs
-
diff --git a/lib/GHCup/Utils/Prelude/Posix.hs b/lib/GHCup/Utils/Prelude/Posix.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/Prelude/Posix.hs
+++ /dev/null
@@ -1,20 +0,0 @@
-module GHCup.Utils.Prelude.Posix where
-
-import System.Directory
-import System.Posix.Files
-
-
-isWindows, isNotWindows :: Bool
-isWindows = False
-isNotWindows = not isWindows
-
-
-moveFile :: FilePath -> FilePath -> IO ()
-moveFile = rename
-
-
-moveFilePortable :: FilePath -> FilePath -> IO ()
-moveFilePortable from to = do
-  copyFile from to
-  removeFile from
-  
diff --git a/lib/GHCup/Utils/Prelude/Windows.hs b/lib/GHCup/Utils/Prelude/Windows.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/Prelude/Windows.hs
+++ /dev/null
@@ -1,17 +0,0 @@
-module GHCup.Utils.Prelude.Windows where
-
-import qualified System.Win32.File             as Win32
-
-
-isWindows, isNotWindows :: Bool
-isWindows = True
-isNotWindows = not isWindows
-
-
-moveFile :: FilePath -> FilePath -> IO ()
-moveFile from to = Win32.moveFileEx from (Just to) 0
-
-
-moveFilePortable :: FilePath -> FilePath -> IO ()
-moveFilePortable = Win32.moveFile
-
diff --git a/lib/GHCup/Utils/String/QQ.hs b/lib/GHCup/Utils/String/QQ.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/String/QQ.hs
+++ /dev/null
@@ -1,57 +0,0 @@
-{-# LANGUAGE TemplateHaskellQuotes #-}
-
-{-|
-Module      : GHCup.Utils.String.QQ
-Description : String quasi quoters
-Copyright   : (c) Audrey Tang <audreyt@audreyt.org> 2019, Julian Ospald <hasufell@posteo.de> 2020
-License     : LGPL-3.0
-Maintainer  : hasufell@hasufell.de
-Stability   : experimental
-Portability : portable
-
-QuasiQuoter for non-interpolated strings, texts and bytestrings.
-
-The "s" quoter contains a multi-line string with no interpolation at all,
-except that the leading newline is trimmed and carriage returns stripped.
-
-@
-{-\# LANGUAGE QuasiQuotes #-}
-import Data.Text (Text)
-import Data.String.QQ
-foo :: Text -- "String", "ByteString" etc also works
-foo = [s|
-Well here is a
-    multi-line string!
-|]
-@
-
-Any instance of the IsString type is permitted.
-
-(For GHC versions 6, write "[$s||]" instead of "[s||]".)
-
--}
-module GHCup.Utils.String.QQ
-  ( s
-  )
-where
-
-
-import           Data.Char
-import           GHC.Exts                       ( IsString(..) )
-import           Language.Haskell.TH.Quote
-
--- | QuasiQuoter for a non-interpolating ASCII IsString literal.
--- The pattern portion is undefined.
-s :: QuasiQuoter
-s = QuasiQuoter
-  (\s' -> case all isAscii s' of
-    True  -> (\a -> [|fromString a|]) . trimLeadingNewline . removeCRs $ s'
-    False -> fail "Not ascii"
-  )
-  (error "Cannot use s as a pattern")
-  (error "Cannot use s as a type")
-  (error "Cannot use s as a dec")
- where
-  removeCRs = filter (/= '\r')
-  trimLeadingNewline ('\n' : xs) = xs
-  trimLeadingNewline xs          = xs
diff --git a/lib/GHCup/Utils/Version/QQ.hs b/lib/GHCup/Utils/Version/QQ.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/Version/QQ.hs
+++ /dev/null
@@ -1,107 +0,0 @@
-{-# OPTIONS_GHC -Wno-orphans    #-}
-{-# LANGUAGE CPP                #-}
-{-# LANGUAGE DeriveDataTypeable #-}
-{-# LANGUAGE DeriveLift         #-}
-{-# LANGUAGE FlexibleInstances  #-}
-{-# LANGUAGE StandaloneDeriving #-}
-{-# LANGUAGE TemplateHaskellQuotes #-}
-
-
-{-|
-Module      : GHCup.Utils.Version.QQ
-Description : Version quasi-quoters
-Copyright   : (c) Julian Ospald, 2020
-License     : LGPL-3.0
-Maintainer  : hasufell@hasufell.de
-Stability   : experimental
-Portability : portable
--}
-module GHCup.Utils.Version.QQ where
-
-import           Data.Data
-import           Data.Text                      ( Text )
-import           Data.Versions
-#if !MIN_VERSION_base(4,13,0)
-import           GHC.Base
-#endif
-import           Language.Haskell.TH
-import           Language.Haskell.TH.Quote      ( QuasiQuoter(..) )
-import           Language.Haskell.TH.Syntax     ( Lift
-                                                , dataToExpQ
-                                                )
-import qualified Data.Text                     as T
-import qualified Language.Haskell.TH.Syntax    as TH
-
-
-
-deriving instance Data Versioning
-deriving instance Lift Versioning
-deriving instance Data Version
-deriving instance Lift Version
-deriving instance Data SemVer
-deriving instance Lift SemVer
-deriving instance Data Mess
-deriving instance Lift Mess
-deriving instance Data MChunk
-deriving instance Lift MChunk
-deriving instance Data PVP
-deriving instance Lift PVP
-deriving instance Lift VSep
-deriving instance Data VSep
-deriving instance Lift VUnit
-deriving instance Data VUnit
-
-#if !MIN_VERSION_base(4,13,0)
-deriving instance Lift (NonEmpty Word)
-deriving instance Lift (NonEmpty VChunk)
-deriving instance Lift (NonEmpty MChunk)
-deriving instance Lift (NonEmpty VUnit)
-#endif
-
-qq :: (Text -> Q Exp) -> QuasiQuoter
-qq quoteExp' = QuasiQuoter
-  { quoteExp  = \s -> quoteExp' . T.pack $ s
-  , quotePat  = \_ ->
-    fail "illegal QuasiQuote (allowed as expression only, used as a pattern)"
-  , quoteType = \_ ->
-    fail "illegal QuasiQuote (allowed as expression only, used as a type)"
-  , quoteDec  = \_ -> fail
-    "illegal QuasiQuote (allowed as expression only, used as a declaration)"
-  }
-
-vver :: QuasiQuoter
-vver = qq mkV
- where
-  mkV :: Text -> Q Exp
-  mkV = either (fail . show) liftDataWithText . version
-
-mver :: QuasiQuoter
-mver = qq mkV
- where
-  mkV :: Text -> Q Exp
-  mkV = either (fail . show) liftDataWithText . mess
-
-sver :: QuasiQuoter
-sver = qq mkV
- where
-  mkV :: Text -> Q Exp
-  mkV = either (fail . show) liftDataWithText . semver
-
-vers :: QuasiQuoter
-vers = qq mkV
- where
-  mkV :: Text -> Q Exp
-  mkV = either (fail . show) liftDataWithText . versioning
-
-pver :: QuasiQuoter
-pver = qq mkV
- where
-  mkV :: Text -> Q Exp
-  mkV = either (fail . show) liftDataWithText . pvp
-
--- https://stackoverflow.com/questions/38143464/cant-find-inerface-file-declaration-for-variable
-liftText :: T.Text -> Q Exp
-liftText txt = AppE (VarE 'T.pack) <$> TH.lift (T.unpack txt)
-
-liftDataWithText :: Data a => a -> Q Exp
-liftDataWithText = dataToExpQ (fmap liftText . cast)
diff --git a/lib/GHCup/Utils/Windows.hs b/lib/GHCup/Utils/Windows.hs
deleted file mode 100644
--- a/lib/GHCup/Utils/Windows.hs
+++ /dev/null
@@ -1,48 +0,0 @@
-{-# LANGUAGE CPP                   #-}
-{-# LANGUAGE DataKinds             #-}
-{-# LANGUAGE FlexibleContexts      #-}
-{-# LANGUAGE OverloadedStrings     #-}
-
-module GHCup.Utils.Windows where
-
-
-import           Control.Exception.Safe
-import           Control.Monad
-#if !MIN_VERSION_base(4,13,0)
-import           Control.Monad.Fail             ( MonadFail )
-#endif
-import           Data.Bits
-
-import           System.Win32.Console
-import           System.Win32.File     hiding ( copyFile )
-import           System.Win32.Types
-
-
-
-
--- | Enables ANSI support on windows, does nothing on unix.
---
--- Returns 'Left str' on errors and 'Right bool' on success, where
--- 'bool' markes whether ansi support was already enabled.
---
--- This function never crashes.
---
--- Rip-off of https://docs.rs/ansi_term/0.12.1/x86_64-pc-windows-msvc/src/ansi_term/windows.rs.html#10-61
-enableAnsiSupport :: IO (Either String Bool)
-enableAnsiSupport = handleIO (pure . Left . displayException) $ do
-  -- ref: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
-  -- Using `CreateFileW("CONOUT$", ...)` to retrieve the console handle works correctly even if STDOUT and/or STDERR are redirected
-  h <- createFile "CONOUT$" (gENERIC_WRITE .|. gENERIC_READ)
-    fILE_SHARE_WRITE Nothing oPEN_EXISTING 0 Nothing
-  when (h == iNVALID_HANDLE_VALUE ) $ fail "invalid handle value"
-
-  -- ref: https://docs.microsoft.com/en-us/windows/console/getconsolemode
-  m <- getConsoleMode h
-
-  -- VT processing not already enabled?
-  if m .&. eNABLE_VIRTUAL_TERMINAL_PROCESSING == 0
-  -- https://docs.microsoft.com/en-us/windows/console/setconsolemode
-  then setConsoleMode h (m .|. eNABLE_VIRTUAL_TERMINAL_PROCESSING)
-    >> pure (Right False)
-  else pure (Right True)
-
diff --git a/lib/GHCup/Version.hs b/lib/GHCup/Version.hs
--- a/lib/GHCup/Version.hs
+++ b/lib/GHCup/Version.hs
@@ -16,12 +16,18 @@
 import           Paths_ghcup (version)
 
 import           Data.Version (Version(versionBranch))
-import           Data.Versions hiding (version)
 import           URI.ByteString
 import           URI.ByteString.QQ
 
 import qualified Data.List.NonEmpty            as NE
 import qualified Data.Text                     as T
+import qualified Data.Versions as V
+import Control.Exception.Safe (MonadThrow)
+import Data.Text (Text)
+import Data.List.NonEmpty (NonEmpty((:|)))
+import Data.List (intersperse)
+import Control.Monad.Catch (throwM)
+import GHCup.Errors (ParseError(..))
 
 -- | This reflects the API version of the YAML.
 --
@@ -31,22 +37,72 @@
 ghcupURL = [uri|https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-0.0.7.yaml|]
 
 -- | The current ghcup version.
-ghcUpVer :: PVP
-ghcUpVer = PVP . NE.fromList . fmap fromIntegral $ versionBranch version
+ghcUpVer :: V.PVP
+ghcUpVer = V.PVP . NE.fromList . fmap fromIntegral $ versionBranch version
 
 -- | ghcup version as numeric string.
 numericVer :: String
-numericVer = T.unpack . prettyPVP $ ghcUpVer
+numericVer = T.unpack . V.prettyPVP $ ghcUpVer
 
-versionCmp :: Versioning -> VersionCmp -> Bool
+versionCmp :: V.Versioning -> VersionCmp -> Bool
 versionCmp ver1 (VR_gt ver2)   = ver1 > ver2
 versionCmp ver1 (VR_gteq ver2) = ver1 >= ver2
 versionCmp ver1 (VR_lt ver2)   = ver1 < ver2
 versionCmp ver1 (VR_lteq ver2) = ver1 <= ver2
 versionCmp ver1 (VR_eq ver2)   = ver1 == ver2
 
-versionRange :: Versioning -> VersionRange -> Bool
+versionRange :: V.Versioning -> VersionRange -> Bool
 versionRange ver' (SimpleRange cmps) = and $ fmap (versionCmp ver') cmps
 versionRange ver' (OrRange cmps range) = 
   versionRange ver' (SimpleRange cmps) || versionRange ver' range
 
+pvpToVersion :: MonadThrow m => V.PVP -> Text -> m V.Version
+pvpToVersion pvp_ rest =
+  either (\_ -> throwM $ ParseError "Couldn't convert PVP to Version") pure . V.version . (<> rest) . V.prettyPVP $ pvp_
+
+-- | Convert a version to a PVP and unparsable rest.
+--
+-- -- prop> \v -> let (Just (pvp', r)) = versionToPVP v in pvpToVersion pvp' r === Just v
+versionToPVP :: MonadThrow m => V.Version -> m (V.PVP, Text)
+versionToPVP (V.Version (Just _) _ _ _) = throwM $ ParseError "Unexpected epoch"
+versionToPVP v = either (\_ -> (, rest v) <$> alternative v) (pure . (, mempty)) . V.pvp . V.prettyVer $ v
+ where
+  alternative :: MonadThrow m => V.Version -> m V.PVP
+  alternative v' = case NE.takeWhile isDigit (V._vChunks v') of
+    [] -> throwM $ ParseError "Couldn't convert Version to PVP"
+    xs -> pure $ pvpFromList (unsafeDigit <$> xs)
+
+  rest :: V.Version -> Text
+  rest (V.Version _ cs pr me) =
+    let chunks = NE.dropWhile isDigit cs
+        ver = intersperse (T.pack ".") . chunksAsT $ chunks
+        me' = maybe [] (\m -> [T.pack "+",m]) me
+        pr' = foldable [] (T.pack "-" :) $ intersperse (T.pack ".") (chunksAsT pr)
+        prefix = case (ver, pr', me') of
+                   (_:_, _, _) -> T.pack "."
+                   _           -> T.pack ""
+    in prefix <> mconcat (ver <> pr' <> me')
+   where
+    chunksAsT :: Functor t => t V.VChunk -> t Text
+    chunksAsT = fmap (foldMap f)
+      where
+        f :: V.VUnit -> Text
+        f (V.Digits i) = T.pack $ show i
+        f (V.Str s)    = s
+
+    foldable :: Foldable f => f b -> (f a -> f b) -> f a -> f b
+    foldable d g f | null f    = d
+                   | otherwise = g f
+
+
+
+  isDigit :: V.VChunk -> Bool
+  isDigit (V.Digits _ :| []) = True
+  isDigit _                = False
+
+  unsafeDigit :: V.VChunk -> Int
+  unsafeDigit (V.Digits x :| []) = fromIntegral x
+  unsafeDigit _ = error "unsafeDigit: wrong input"
+
+pvpFromList :: [Int] -> V.PVP
+pvpFromList = V.PVP . NE.fromList . fmap fromIntegral
diff --git a/test/GHCup/Utils/FileSpec.hs b/test/GHCup/Utils/FileSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/GHCup/Utils/FileSpec.hs
@@ -0,0 +1,58 @@
+module GHCup.Utils.FileSpec where
+
+import           GHCup.Prelude.File
+
+import           Data.List
+import           System.Directory
+import           System.FilePath
+import           System.IO.Unsafe
+import qualified Streamly.Prelude              as S
+
+import           Test.Hspec
+
+
+
+spec :: Spec
+spec = do
+  describe "GHCup.Utils.File" $ do
+    it "getDirectoryContentsRecursiveBFS" $ do
+      l1 <- sort <$> S.toList (getDirectoryContentsRecursiveBFSUnsafe "lib")
+      l2 <- sort <$> getDirectoryContentsRecursiveLazy "lib"
+      not (null l1) `shouldBe` True
+      not (null l2) `shouldBe` True
+      l1 `shouldBe` l2
+    it "getDirectoryContentsRecursiveDFS" $ do
+      l1 <- sort <$> S.toList (getDirectoryContentsRecursiveDFSUnsafe "lib")
+      l2 <- sort <$> getDirectoryContentsRecursiveLazy "lib"
+      not (null l1) `shouldBe` True
+      not (null l2) `shouldBe` True
+      l1 `shouldBe` l2
+
+
+getDirectoryContentsRecursiveLazy :: FilePath -> IO [FilePath]
+getDirectoryContentsRecursiveLazy topdir = recurseDirectories [""]
+  where
+    recurseDirectories :: [FilePath] -> IO [FilePath]
+    recurseDirectories []         = return []
+    recurseDirectories (dir:dirs) = unsafeInterleaveIO $ do
+      (files, dirs') <- collect [] [] =<< getDirectoryContents (topdir </> dir)
+      files' <- recurseDirectories (dirs' ++ dirs)
+      return (files ++ files')
+
+      where
+        collect files dirs' []              = return (reverse files
+                                                     ,reverse dirs')
+        collect files dirs' (entry:entries) | ignore entry
+                                            = collect files dirs' entries
+        collect files dirs' (entry:entries) = do
+          let dirEntry = dir </> entry
+          isDirectory <- doesDirectoryExist (topdir </> dirEntry)
+          if isDirectory
+            then collect files (dirEntry:dirs') entries
+            else collect (dirEntry:files) dirs' entries
+
+        ignore ['.']      = True
+        ignore ['.', '.'] = True
+        ignore _          = False
+
+
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -1,10 +1,9 @@
 import Test.Hspec.Runner
-import Test.Hspec.Formatters
 import qualified Spec
 
 
 main :: IO ()
 main =
   hspecWith
-    defaultConfig { configFormatter = Just progress }
+    defaultConfig
     Spec.spec