diff --git a/ChangeLog.md b/ChangeLog.md
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--- /dev/null
+++ b/ChangeLog.md
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+# Revision history for stack-clean-old-work
+
+## 0.1 (2020-09-xx)
+- initial release with project and snapshots subcommands
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright (c) 2020, Jens Petersen
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Jens Petersen nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/Main.hs b/Main.hs
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--- /dev/null
+++ b/Main.hs
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+{-# LANGUAGE CPP #-}
+
+import Control.Monad.Extra
+import Data.List.Extra
+import Data.Maybe
+import Data.Version.Extra
+import SimpleCmd
+#if MIN_VERSION_simple_cmd(0,2,1)
+  hiding (ifM, whenM)
+#endif
+import SimpleCmdArgs
+import System.Directory
+import System.FilePath
+import Text.Printf
+
+import Paths_stack_clean_old (version)
+
+main :: IO ()
+main = do
+  simpleCmdArgs (Just version) "Stack clean up tool"
+    "Cleans away old stack-work builds (and pending: stack snapshots) to recover diskspace." $
+    subcommands
+    [ Subcommand "project" "Commands for project .stack-work builds" $
+      subcommands
+      [ Subcommand "size" "Total size of project's .stack-work/install" $
+        sizeStackWork <$> dirOption <*> notHumanOpt
+      , Subcommand "list" "list builds in .stack-work/install per ghc version" $
+        listGhcSnapshots . setStackWorkDir <$> dirOption <*> optional ghcVerArg
+      , Subcommand "remove-version" "remove builds in .stack-work/install for a ghc version" $
+        cleanGhcSnapshots . setStackWorkDir <$> dirOption <*> ghcVerArg
+      , Subcommand "remove-older" "purge older builds in .stack-work/install" $
+        cleanOldStackWork <$> keepOption <*> optional (strArg "PROJECTDIR")
+      ]
+    , Subcommand "snapshots" "Commands for ~/.stack/snapshots" $
+      subcommands
+      [ Subcommand "size" "Total size of all stack build snapshots" $
+        sizeSnapshots <$> notHumanOpt
+      , Subcommand "list" "List build snapshots per ghc version" $
+        listGhcSnapshots setStackSnapshotsDir <$> optional ghcVerArg
+      , Subcommand "remove-version" "Remove build snapshots for a ghc version" $
+        cleanGhcSnapshots setStackSnapshotsDir <$> ghcVerArg
+      ]
+    , Subcommand "ghc" "Commands on stack's ghc compiler installations" $
+      subcommands
+      [ Subcommand "size" "Total size of installed stack ghc compilers" $
+        sizeGhcInstalls <$> notHumanOpt
+      , Subcommand "list" "List installed stack ghc compiler versions" $
+        listGhcInstallation <$> optional ghcVerArg
+      , Subcommand "remove-version" "Remove installation of a stack ghc compiler version" $
+        removeGhcVersionInstallation <$> ghcVerArg
+      ]
+
+    ]
+  where
+    notHumanOpt = switchWith 'H' "not-human-size" "Do not use du --human-readable"
+
+    dirOption = optional (strOptionWith 'd' "dir" "PROJECTDIR" "Path to project")
+    ghcVerArg = strArg "GHCVER"
+
+    keepOption = positive <$> optionalWith auto 'k' "keep" "INT" "number of project builds per ghc version" 5
+
+    positive :: Int -> Int
+    positive n = if n > 0 then n else error' "Must be positive integer"
+
+stackWorkInstall :: FilePath
+stackWorkInstall = ".stack-work/install"
+
+sizeStackWork :: Maybe FilePath -> Bool -> IO ()
+sizeStackWork mdir nothuman = do
+  let path = fromMaybe "" mdir </> stackWorkInstall
+  whenM (doesDirectoryExist path) $
+    cmd_ "du" $ ["-h" | not nothuman] ++ ["-s", path]
+
+printTotalGhcSize :: [FilePath] -> IO ()
+printTotalGhcSize ds = do
+  total <- head . words . last <$> cmdLines "du" ("-shc":ds)
+  printf "%4s  %-6s (%d dirs)\n" total ((takeFileName . head) ds) (length ds)
+
+setStackWorkDir :: Maybe FilePath -> IO ()
+setStackWorkDir mdir = do
+  whenJust mdir $ \ dir -> setCurrentDirectory dir
+  switchToSystemDirUnder stackWorkInstall
+
+setStackSnapshotsDir :: IO ()
+setStackSnapshotsDir = do
+  home <- getHomeDirectory
+  switchToSystemDirUnder $ home </> ".stack/snapshots"
+
+getSnapshotDirs :: IO [FilePath]
+getSnapshotDirs = do
+  lines <$> shell ( unwords $ "ls" : ["-d", "*/*"])
+
+takeGhcSnapshots :: String -> [FilePath] -> [FilePath]
+takeGhcSnapshots ghcver =
+  map takeDirectory . filter ((== ghcver) . takeFileName)
+
+sizeSnapshots :: Bool -> IO ()
+sizeSnapshots nothuman = do
+  home <- getHomeDirectory
+  cmd_ "du" $ ["-h" | not nothuman] ++ ["-s", home </> ".stack/snapshots"]
+
+listGhcSnapshots :: IO () -> Maybe String -> IO ()
+listGhcSnapshots setdir mghcver = do
+  setdir
+  dirs <- sortOn (readVersion . takeFileName) <$> getSnapshotDirs
+  case mghcver of
+    Nothing -> do
+      let ghcs = groupOn takeFileName dirs
+      mapM_ printTotalGhcSize ghcs
+    Just ghcver -> do
+      let ds = takeGhcSnapshots ghcver dirs
+      unless (null dirs) $
+        cmd_ "du" ("-shc":ds)
+
+cleanGhcSnapshots :: IO () -> String -> IO ()
+cleanGhcSnapshots setDir ghcver = do
+  setDir
+  dirs <- takeGhcSnapshots ghcver <$> getSnapshotDirs
+  mapM_ removeDirectoryRecursive dirs
+  putStrLn $ show (length dirs) ++ " snapshots removed for " ++ ghcver
+
+switchToSystemDirUnder :: FilePath -> IO ()
+switchToSystemDirUnder dir = do
+  ifM (doesDirectoryExist dir)
+    (setCurrentDirectory dir)
+    (error' $ dir ++ "not found")
+  systems <- listDirectory "."
+  let system = case systems of
+        [] -> error' $ "No OS system in " ++ dir
+        [sys] -> sys
+        _ -> error' "More than one OS systems found " ++ dir ++ " (unsupported)"
+  setCurrentDirectory system
+
+cleanOldStackWork :: Int -> Maybe FilePath -> IO ()
+cleanOldStackWork keep mdir = do
+  setStackWorkDir mdir
+  dirs <- sortOn takeFileName . lines <$> shell ( unwords $ "ls" : ["-d", "*/*"])
+  let ghcs = groupOn takeFileName dirs
+  mapM_ removeOlder ghcs
+  where
+    removeOlder :: [FilePath] -> IO ()
+    removeOlder dirs = do
+      let ghcver = (takeFileName . head) dirs
+      oldfiles <- drop keep . reverse <$> sortedByAge
+      mapM_ (removeDirectoryRecursive . takeDirectory) oldfiles
+      unless (null oldfiles) $
+        putStrLn $ show (length oldfiles) ++ " dirs removed for " ++ ghcver
+      where
+        sortedByAge = do
+          fileTimes <- mapM newestTimeStamp dirs
+          return $ map fst $ sortOn snd fileTimes
+
+        newestTimeStamp dir = do
+          withCurrentDirectory dir $ do
+            files <- listDirectory "."
+            timestamp <- maximum <$> mapM getModificationTime files
+            return (dir, timestamp)
+
+stackProgramsDir :: FilePath
+stackProgramsDir = ".stack/programs"
+
+sizeGhcInstalls :: Bool -> IO ()
+sizeGhcInstalls nothuman = do
+  home <- getHomeDirectory
+  cmd_ "du" $ ["-h" | not nothuman] ++ ["-s", home </> stackProgramsDir]
+
+setStackProgramsDir :: IO ()
+setStackProgramsDir = do
+  home <- getHomeDirectory
+  switchToSystemDirUnder $ home </> stackProgramsDir
+
+getGhcInstallDirs :: IO [FilePath]
+getGhcInstallDirs = do
+  setStackProgramsDir
+  listDirectory "." >>= fmap sort . filterM doesDirectoryExist
+
+listGhcInstallation :: Maybe String -> IO ()
+listGhcInstallation mghcver = do
+  dirs <- getGhcInstallDirs
+  mapM_ putStrLn $ case mghcver of
+    Nothing -> dirs
+    Just ghcver -> filter (ghcver `isSuffixOf`) dirs
+
+removeGhcVersionInstallation :: String -> IO ()
+removeGhcVersionInstallation ghcver = do
+  dirs <- getGhcInstallDirs
+  case filter (ghcver `isSuffixOf`) dirs of
+    [] -> error' $ "stack ghc compiler version " ++ ghcver ++ " not found"
+    [g] -> removeDirectoryRecursive g >> removeFile (g <.> "installed")
+    _ -> error' "more than one match found!!"
diff --git a/README.md b/README.md
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+++ b/README.md
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+# stack-clean-old
+
+A small tool to clean away older Haskell [stack](https://docs.haskellstack.org)
+snapshot builds and ghc versions, to recover diskspace.
+
+## Usage
+```
+stack-clean-old [project|snapshots|ghc] [size|list|remove-version] [GHCVER]
+```
+These commands act respectively on:
+
+- the current local project (`.stack-work/install/`)
+- the user's stack snapshot builds (`~/.stack/snapshots/`)
+- installed stack ghc compilers  (`~/.stack/programs/`).
+
+`size`:
+    prints the total size of the above directory
+    (`size` does not take a GHCVER argument).
+
+`list`:
+    shows the total size and number of snapshots per ghc version
+    (the GHCVER argument is optional).
+
+`remove-version`:
+    removes all snapshots for the specified ghc version
+    (the GHCVER argument is required).
+
+NB: If you remove all snapshot builds for a version of ghc, then you would have to rebuild again for any projects still using them, so removal should be used cautiously, but it can recover a lot of diskspace.
+
+### Purging older stack project builds
+```
+stack-clean-old project remove-older
+```
+This command removes older stack builds from `.stack-work/install/`.
+By default it keeps 5 newest builds per ghc version.
+
+The preservation/deletion is calculated and done per ghc version.
+
+NB: If you regularly build multiple branches/tags against the same LTS or ghc version then it is probably safer to avoid using `remove-older`.
+
+## Installation
+
+Run `stack install` or `cabal install`
+
+## Contributing
+BSD license
+
+Project: https://github.com/juhp/stack-clean-old
+
+## Warning disclaimer
+Use at your own risk.
+
+The author takes no responsibility for any loss or damaged caused by using
+this tool. Bug reports, suggestions, and improvements are welcome.
diff --git a/stack-clean-old.cabal b/stack-clean-old.cabal
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+++ b/stack-clean-old.cabal
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+name:                stack-clean-old
+version:             0.1
+synopsis:            Clean away old stack build artefacts
+description:
+        A tool for cleaning away old stack snapshots and stack-work builds
+        to recover diskspace.
+license:             BSD3
+license-file:        LICENSE
+author:              Jens Petersen <juhpetersen@gmail.com>
+maintainer:          Jens Petersen <juhpetersen@gmail.com>
+copyright:           2020  Jens Petersen <juhpetersen@gmail.com>
+homepage:            https://github.com/juhp/stack-clean-old
+bug-reports:         https://github.com/juhp/stack-clean-old/issues
+build-type:          Simple
+category:            Distribution
+extra-doc-files:     README.md
+                     ChangeLog.md
+cabal-version:       1.18
+
+source-repository head
+  type:                git
+  location:            https://github.com/juhp/stack-clean-old.git
+
+executable stack-clean-old
+  main-is:             Main.hs
+  other-modules:       Paths_stack_clean_old
+--  hs-source-dirs:      app
+  build-depends:       base < 5
+                     , directory
+                     , extra
+                     , filepath
+                     , simple-cmd >= 0.1.4
+                     , simple-cmd-args >= 0.1.2
+  default-language:    Haskell2010
+  ghc-options:         -Wall
+  if impl(ghc >= 8.0)
+    ghc-options:       -Wcompat
+                       -Widentities
+                       -Wincomplete-uni-patterns
+                       -Wincomplete-record-updates
+                       -Wredundant-constraints
+  if impl(ghc >= 8.2)
+    ghc-options:       -fhide-source-paths
+  if impl(ghc >= 8.4)
+    ghc-options:       -Wmissing-export-lists
+                       -Wpartial-fields