diff --git a/shake-bench.cabal b/shake-bench.cabal
--- a/shake-bench.cabal
+++ b/shake-bench.cabal
@@ -1,6 +1,6 @@
 cabal-version: 2.2
 name:          shake-bench
-version:       0.1.0.3
+version:       0.1.1.0
 synopsis:      Build rules for historical benchmarking
 license:       Apache-2.0
 license-file:  LICENSE
@@ -29,6 +29,7 @@
         filepath,
         lens,
         lens-aeson,
+        mtl,
         shake,
         text
   default-language: Haskell2010
diff --git a/src/Development/Benchmark/Rules.hs b/src/Development/Benchmark/Rules.hs
--- a/src/Development/Benchmark/Rules.hs
+++ b/src/Development/Benchmark/Rules.hs
@@ -1,704 +1,719 @@
-{-# LANGUAGE AllowAmbiguousTypes       #-}
-{-# LANGUAGE ApplicativeDo             #-}
-{-# LANGUAGE ConstraintKinds           #-}
-{-# LANGUAGE DeriveAnyClass            #-}
-{-# LANGUAGE DerivingStrategies        #-}
-{-# LANGUAGE DuplicateRecordFields     #-}
-{-# LANGUAGE ExistentialQuantification #-}
-{-# LANGUAGE OverloadedStrings         #-}
-{-# LANGUAGE RankNTypes                #-}
-{-# LANGUAGE TypeFamilies              #-}
-
-{- |
-    This module provides a bunch of Shake rules to build multiple revisions of a
-    project and analyse their performance.
-
-    It assumes a project bench suite composed of examples that runs a fixed set
-    of experiments on every example
-
-    Your code must implement all of the GetFoo oracles and the IsExample class,
-    instantiate the Shake rules, and probably 'want' a set of targets.
-
-    The results of the benchmarks and the analysis are recorded in the file
-    system, using the following structure:
-
-    <build-folder>
-    ├── binaries
-    │   └── <git-reference>
-    │        ├── ghc.path                         - path to ghc used to build the executable
-    │        └── <executable>                     - binary for this version
-    │        └── commitid                         - Git commit id for this reference
-    ├─ <example>
-    │   ├── results.csv                           - aggregated results for all the versions
-    │   └── <git-reference>
-    │       ├── <experiment>.gcStats.log          - RTS -s output
-    │       ├── <experiment>.csv                  - stats for the experiment
-    │       ├── <experiment>.svg                  - Graph of bytes over elapsed time
-    │       ├── <experiment>.diff.svg             - idem, including the previous version
-    │       ├── <experiment>.heap.svg             - Heap profile
-    │       ├── <experiment>.log                  - bench stdout
-    │       └── results.csv                       - results of all the experiments for the example
-    ├── results.csv        - aggregated results of all the experiments and versions
-    └── <experiment>.svg   - graph of bytes over elapsed time, for all the included versions
-
-   For diff graphs, the "previous version" is the preceding entry in the list of versions
-   in the config file. A possible improvement is to obtain this info via `git rev-list`.
- -}
-{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
-module Development.Benchmark.Rules
-  (
-      buildRules, MkBuildRules(..),
-      benchRules, MkBenchRules(..), BenchProject(..), ProfilingMode(..),
-      csvRules,
-      svgRules,
-      heapProfileRules,
-      phonyRules,
-      allTargetsForExample,
-      GetExample(..), GetExamples(..),
-      IsExample(..), RuleResultForExample,
-      GetExperiments(..),
-      GetVersions(..),
-      GetCommitId(..),
-      GetBuildSystem(..),
-      BuildSystem(..), findGhcForBuildSystem,
-      Escaped(..), Unescaped(..), escapeExperiment, unescapeExperiment,
-      GitCommit
-
-  ) where
-
-import           Control.Applicative
-import           Control.Lens                              ((^.))
-import           Control.Monad
-import           Data.Aeson                                (FromJSON (..),
-                                                            ToJSON (..),
-                                                            Value (..), object,
-                                                            (.!=), (.:?), (.=))
-import           Data.Aeson.Lens                           (_Object)
-import           Data.Char                                 (isDigit)
-import           Data.List                                 (find, isInfixOf,
-                                                            stripPrefix,
-                                                            transpose)
-import           Data.List.Extra                           (lower)
-import           Data.Maybe                                (fromMaybe)
-import           Data.String                               (fromString)
-import           Data.Text                                 (Text)
-import qualified Data.Text                                 as T
-import           Development.Shake
-import           Development.Shake.Classes                 (Binary, Hashable,
-                                                            NFData, Typeable)
-import           GHC.Exts                                  (IsList (toList),
-                                                            fromList)
-import           GHC.Generics                              (Generic)
-import           GHC.Stack                                 (HasCallStack)
-import qualified Graphics.Rendering.Chart.Backend.Diagrams as E
-import qualified Graphics.Rendering.Chart.Easy             as E
-import           System.Directory                          (createDirectoryIfMissing,
-                                                            findExecutable,
-                                                            renameFile)
-import           System.FilePath
-import           System.Time.Extra                         (Seconds)
-import qualified Text.ParserCombinators.ReadP              as P
-import           Text.Printf
-import           Text.Read                                 (Read (..), get,
-                                                            readMaybe,
-                                                            readP_to_Prec)
-
-newtype GetExperiments = GetExperiments () deriving newtype (Binary, Eq, Hashable, NFData, Show)
-newtype GetVersions = GetVersions () deriving newtype (Binary, Eq, Hashable, NFData, Show)
-newtype GetParent = GetParent Text deriving newtype (Binary, Eq, Hashable, NFData, Show)
-newtype GetCommitId = GetCommitId String deriving newtype (Binary, Eq, Hashable, NFData, Show)
-newtype GetBuildSystem = GetBuildSystem () deriving newtype (Binary, Eq, Hashable, NFData, Show)
-newtype GetExample = GetExample String deriving newtype (Binary, Eq, Hashable, NFData, Show)
-newtype GetExamples = GetExamples () deriving newtype (Binary, Eq, Hashable, NFData, Show)
-
-type instance RuleResult GetExperiments = [Unescaped String]
-type instance RuleResult GetVersions = [GitCommit]
-type instance RuleResult GetParent = Text
-type instance RuleResult GetCommitId = String
-type instance RuleResult GetBuildSystem = BuildSystem
-
-type RuleResultForExample e =
-    ( RuleResult GetExample ~ Maybe e
-    , RuleResult GetExamples ~ [e]
-    , IsExample e)
-
--- | Knowledge needed to run an example
-class (Binary e, Eq e, Hashable e, NFData e, Show e, Typeable e) => IsExample e where
-    getExampleName :: e -> String
-
---------------------------------------------------------------------------------
-
-allTargetsForExample :: IsExample e => ProfilingMode -> FilePath -> e -> Action [FilePath]
-allTargetsForExample prof baseFolder ex = do
-    experiments <- askOracle $ GetExperiments ()
-    versions    <- askOracle $ GetVersions ()
-    let buildFolder = baseFolder </> profilingPath prof
-    return $
-        [buildFolder </> getExampleName ex </> "results.csv"]
-        ++ [ buildFolder </> getExampleName ex </> escaped (escapeExperiment e) <.> "svg"
-             | e <- experiments
-           ]
-        ++ [ buildFolder </>
-             getExampleName ex </>
-             T.unpack (humanName ver) </>
-             escaped (escapeExperiment e) <.> mode
-             | e <- experiments,
-               ver <- versions,
-               mode <- ["svg", "diff.svg"] ++ ["heap.svg" | prof /= NoProfiling]
-           ]
-
-allBinaries :: FilePath -> String -> Action [FilePath]
-allBinaries buildFolder executableName = do
-    versions <- askOracle $ GetVersions ()
-    return $
-        [ buildFolder </> "binaries" </> T.unpack (humanName ver) </> executableName
-        | ver <- versions]
-
--- | Generate a set of phony rules:
---     * <prefix>all
---     * <prefix><example>  for each example
-phonyRules
-    :: (Traversable t, IsExample e)
-    => String         -- ^ prefix
-    -> String         -- ^ Executable name
-    -> ProfilingMode
-    -> FilePath
-    -> t e
-    -> Rules ()
-phonyRules prefix executableName prof buildFolder examples = do
-    forM_ examples $ \ex ->
-        phony (prefix <> getExampleName ex) $ need =<<
-            allTargetsForExample prof buildFolder ex
-    phony (prefix <> "all") $ do
-        exampleTargets <- forM examples $ \ex ->
-            allTargetsForExample prof buildFolder ex
-        need $ (buildFolder </> profilingPath prof </> "results.csv")
-             : concat exampleTargets
-    phony (prefix <> "all-binaries") $ need =<< allBinaries buildFolder executableName
---------------------------------------------------------------------------------
-type OutputFolder = FilePath
-
-data MkBuildRules buildSystem = MkBuildRules
-  { -- | Return the path to the GHC executable to use for the project found in the cwd
-    findGhc            :: buildSystem -> FilePath -> IO FilePath
-    -- | Name of the binary produced by 'buildProject'
-  , executableName     :: String
-    -- | An action that captures the source dependencies, used for the HEAD build
-  , projectDepends     :: Action ()
-    -- | Build the project found in the cwd and save the build artifacts in the output folder
-  , buildProject       :: buildSystem
-                       -> [CmdOption]
-                       -> OutputFolder
-                       -> Action ()
-  }
-
--- | Rules that drive a build system to build various revisions of a project
-buildRules :: FilePattern -> MkBuildRules BuildSystem -> Rules ()
--- TODO generalize BuildSystem
-buildRules build MkBuildRules{..} = do
-  -- query git for the commitid for a version
-  build -/- "binaries/*/commitid" %> \out -> do
-      alwaysRerun
-
-      let [_,_,ver,_] = splitDirectories out
-      mbEntry <- find ((== T.pack ver) . humanName) <$> askOracle (GetVersions ())
-      let gitThing :: String
-          gitThing = maybe ver (T.unpack . gitName) mbEntry
-      Stdout commitid <- command [] "git" ["rev-list", "-n", "1", gitThing]
-      writeFileChanged out $ init commitid
-
-  -- build rules for HEAD
-  priority 10 $ [ build -/- "binaries/HEAD/" <> executableName
-                , build -/- "binaries/HEAD/ghc.path"
-                ]
-    &%> \[out, ghcpath] -> do
-      projectDepends
-      liftIO $ createDirectoryIfMissing True $ dropFileName out
-      buildSystem <- askOracle $ GetBuildSystem ()
-      buildProject buildSystem [Cwd "."] (takeDirectory out)
-      ghcLoc <- liftIO $ findGhc buildSystem "."
-      writeFile' ghcpath ghcLoc
-
-  -- build rules for non HEAD revisions
-  [build -/- "binaries/*/" <> executableName
-   ,build -/- "binaries/*/ghc.path"
-   ] &%> \[out, ghcPath] -> do
-      let [_, _binaries, ver, _] = splitDirectories out
-      liftIO $ createDirectoryIfMissing True $ dropFileName out
-      commitid <- readFile' $ takeDirectory out </> "commitid"
-      cmd_ $ "git worktree add bench-temp-" ++ ver ++ " " ++ commitid
-      buildSystem <- askOracle $ GetBuildSystem ()
-      flip actionFinally (cmd_ ("git worktree remove bench-temp-" <> ver <> " --force" :: String)) $ do
-        ghcLoc <- liftIO $ findGhc buildSystem ver
-        buildProject buildSystem [Cwd $ "bench-temp-" <> ver] (".." </> takeDirectory out)
-        writeFile' ghcPath ghcLoc
-
---------------------------------------------------------------------------------
-data MkBenchRules buildSystem example =  forall setup. MkBenchRules
-  {
-  -- | Workaround for Shake not allowing to call 'askOracle' from 'benchProject
-    setupProject :: Action setup
-  -- | An action that invokes the executable to run the benchmark
-  , benchProject :: setup -> buildSystem -> [CmdOption] -> BenchProject example -> Action ()
-  -- | An action that performs any necessary warmup. Will only be invoked once
-  , warmupProject :: buildSystem -> FilePath -> [CmdOption] -> example -> Action ()
-  -- | Name of the executable to benchmark. Should match the one used to 'MkBuildRules'
-  , executableName :: String
-  }
-
-data BenchProject example = BenchProject
-    { outcsv       :: FilePath         -- ^ where to save the CSV output
-    , exePath      :: FilePath         -- ^ where to find the executable for benchmarking
-    , exeExtraArgs :: [String]         -- ^ extra args for the executable
-    , example      :: example          -- ^ example to benchmark
-    , experiment   :: Escaped String   -- ^ experiment to run
-    }
-
-data ProfilingMode = NoProfiling | CheapHeapProfiling Seconds
-    deriving (Eq)
-
-profilingP :: String -> Maybe ProfilingMode
-profilingP "unprofiled" = Just NoProfiling
-profilingP inp | Just delay <- stripPrefix "profiled-" inp, Just i <- readMaybe delay = Just $ CheapHeapProfiling i
-profilingP _ = Nothing
-
-profilingPath :: ProfilingMode -> FilePath
-profilingPath NoProfiling            = "unprofiled"
-profilingPath (CheapHeapProfiling i) = "profiled-" <> show i
-
--- TODO generalize BuildSystem
-benchRules :: RuleResultForExample example => FilePattern -> MkBenchRules BuildSystem example -> Rules ()
-benchRules build MkBenchRules{..} = do
-
-  benchResource <- newResource "ghcide-bench" 1
-  -- warmup an example
-  build -/- "binaries/*/*.warmup" %> \out -> do
-        let [_, _, ver, exampleName] = splitDirectories (dropExtension out)
-        let exePath = build </> "binaries" </> ver </> executableName
-            ghcPath = build </> "binaries" </> ver </> "ghc.path"
-        need [exePath, ghcPath]
-        buildSystem <- askOracle  $ GetBuildSystem ()
-        example <- fromMaybe (error $ "Unknown example " <> exampleName)
-                    <$> askOracle (GetExample exampleName)
-        let exeExtraArgs = []
-            outcsv = ""
-            experiment = Escaped "hover"
-        withResource benchResource 1 $ warmupProject buildSystem exePath
-              [ EchoStdout False,
-                FileStdout out,
-                RemEnv "NIX_GHC_LIBDIR",
-                RemEnv "GHC_PACKAGE_PATH",
-                AddPath [takeDirectory ghcPath, "."] []
-              ]
-              example
-  -- run an experiment
-  priority 0 $
-    [ build -/- "*/*/*/*.csv",
-      build -/- "*/*/*/*.gcStats.log",
-      build -/- "*/*/*/*.output.log",
-      build -/- "*/*/*/*.eventlog",
-      build -/- "*/*/*/*.hp"
-    ] &%> \[outcsv, outGc, outLog, outEventlog, outHp] -> do
-        let [_, flavour, exampleName, ver, exp] = splitDirectories outcsv
-            prof = fromMaybe (error $ "Not a valid profiling mode: " <> flavour) $ profilingP flavour
-        example <- fromMaybe (error $ "Unknown example " <> exampleName)
-                    <$> askOracle (GetExample exampleName)
-        buildSystem <- askOracle  $ GetBuildSystem ()
-        setupRes    <- setupProject
-        liftIO $ createDirectoryIfMissing True $ dropFileName outcsv
-        let exePath    = build </> "binaries" </> ver </> executableName
-            exeExtraArgs =
-                [ "+RTS"
-                , "-l"
-                , "-S" <> outGc]
-             ++ concat
-                [[ "-h"
-                  , "-i" <> show i
-                  , "-qg"]
-                 | CheapHeapProfiling i <- [prof]]
-             ++ ["-RTS"]
-            ghcPath    = build </> "binaries" </> ver </> "ghc.path"
-            warmupPath = build </> "binaries" </> ver </> exampleName <.> "warmup"
-            experiment = Escaped $ dropExtension exp
-        need [exePath, ghcPath, warmupPath]
-        ghcPath <- readFile' ghcPath
-        withResource benchResource 1 $ do
-          benchProject setupRes buildSystem
-              [ EchoStdout False,
-                FileStdout outLog,
-                RemEnv "NIX_GHC_LIBDIR",
-                RemEnv "GHC_PACKAGE_PATH",
-                AddPath [takeDirectory ghcPath, "."] []
-              ]
-              BenchProject {..}
-        liftIO $ renameFile "ghcide.eventlog" outEventlog
-        liftIO $ case prof of
-            CheapHeapProfiling{} -> renameFile "ghcide.hp" outHp
-            NoProfiling          -> writeFile outHp dummyHp
-
-        -- extend csv output with allocation data
-        csvContents <- liftIO $ lines <$> readFile outcsv
-        let header = head csvContents
-            results = tail csvContents
-            header' = header <> ", maxResidency, allocatedBytes"
-        results' <- forM results $ \row -> do
-            (maxResidency, allocations) <- liftIO
-                    (parseMaxResidencyAndAllocations <$> readFile outGc)
-            return $ printf "%s, %s, %s" row (showMB maxResidency) (showMB allocations)
-        let csvContents' = header' : results'
-        writeFileLines outcsv csvContents'
-    where
-        showMB :: Int -> String
-        showMB x = show (x `div` 2^(20::Int)) <> "MB"
-
--- Parse the max residency and allocations in RTS -s output
-parseMaxResidencyAndAllocations :: String -> (Int, Int)
-parseMaxResidencyAndAllocations input =
-    (f "maximum residency", f "bytes allocated in the heap")
-  where
-    inps = reverse $ lines input
-    f label = case find (label `isInfixOf`) inps of
-        Just l  -> read $ filter isDigit $ head $ words l
-        Nothing -> -1
-
-
---------------------------------------------------------------------------------
-
--- | Rules to aggregate the CSV output of individual experiments
-csvRules :: forall example . RuleResultForExample example => FilePattern -> Rules ()
-csvRules build = do
-  -- build results for every experiment*example
-  build -/- "*/*/*/results.csv" %> \out -> do
-      experiments <- askOracle $ GetExperiments ()
-
-      let allResultFiles = [takeDirectory out </> escaped (escapeExperiment e) <.> "csv" | e <- experiments]
-      allResults <- traverse readFileLines allResultFiles
-
-      let header = head $ head allResults
-          results = map tail allResults
-      writeFileChanged out $ unlines $ header : concat results
-
-  -- aggregate all experiments for an example
-  build -/- "*/*/results.csv" %> \out -> do
-    versions <- map (T.unpack . humanName) <$> askOracle (GetVersions ())
-    let allResultFiles = [takeDirectory out </> v </> "results.csv" | v <- versions]
-
-    allResults <- traverse readFileLines allResultFiles
-
-    let header = head $ head allResults
-        results = map tail allResults
-        header' = "version, " <> header
-        results' = zipWith (\v -> map (\l -> v <> ", " <> l)) versions results
-
-    writeFileChanged out $ unlines $ header' : interleave results'
-
-  -- aggregate all examples
-  build -/- "*/results.csv" %> \out -> do
-    examples <- map (getExampleName @example) <$> askOracle (GetExamples ())
-    let allResultFiles = [takeDirectory out </> e </> "results.csv" | e <- examples]
-
-    allResults <- traverse readFileLines allResultFiles
-
-    let header = head $ head allResults
-        results = map tail allResults
-        header' = "example, " <> header
-        results' = zipWith (\e -> map (\l -> e <> ", " <> l)) examples results
-
-    writeFileChanged out $ unlines $ header' : concat results'
-
---------------------------------------------------------------------------------
-
--- | Rules to produce charts for the GC stats
-svgRules :: FilePattern -> Rules ()
-svgRules build = do
-  void $ addOracle $ \(GetParent name) -> findPrev name <$> askOracle (GetVersions ())
-  -- chart GC stats for an experiment on a given revision
-  priority 1 $
-    build -/- "*/*/*/*.svg" %> \out -> do
-      let [_, _, _example, ver, _exp] = splitDirectories out
-      runLog <- loadRunLog (Escaped $ replaceExtension out "csv") ver
-      let diagram = Diagram Live [runLog] title
-          title = ver <> " live bytes over time"
-      plotDiagram True diagram out
-
-  -- chart of GC stats for an experiment on this and the previous revision
-  priority 2 $
-    build -/- "*/*/*/*.diff.svg" %> \out -> do
-      let [b, flav, example, ver, exp_] = splitDirectories out
-          exp = Escaped $ dropExtension2 exp_
-      prev <- fmap T.unpack $ askOracle $ GetParent $ T.pack ver
-
-      runLog <- loadRunLog (Escaped $ replaceExtension (dropExtension out) "csv") ver
-      runLogPrev <- loadRunLog (Escaped $ joinPath [b,flav, example, prev, replaceExtension (dropExtension exp_) "csv"]) prev
-
-      let diagram = Diagram Live [runLog, runLogPrev] title
-          title = show (unescapeExperiment exp) <> " - live bytes over time compared"
-      plotDiagram True diagram out
-
-  -- aggregated chart of GC stats for all the revisions
-  build -/- "*/*/*.svg" %> \out -> do
-    let exp = Escaped $ dropExtension $ takeFileName out
-    versions <- askOracle $ GetVersions ()
-
-    runLogs <- forM (filter include versions) $ \v -> do
-      let v' = T.unpack (humanName v)
-      loadRunLog (Escaped $ takeDirectory out </> v' </> replaceExtension (takeFileName out) "csv") v'
-
-    let diagram = Diagram Live runLogs title
-        title = show (unescapeExperiment exp) <> " - live bytes over time"
-    plotDiagram False diagram out
-
-heapProfileRules :: FilePattern -> Rules ()
-heapProfileRules build = do
-  priority 3 $
-    build -/- "*/*/*/*.heap.svg" %> \out -> do
-      let hpFile = dropExtension2 out <.> "hp"
-      need [hpFile]
-      cmd_ ("hp2pretty" :: String) [hpFile]
-      liftIO $ renameFile (dropExtension hpFile <.> "svg") out
-
-dropExtension2 :: FilePath -> FilePath
-dropExtension2 = dropExtension . dropExtension
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
-
--- | Default build system that handles Cabal and Stack
-data BuildSystem = Cabal | Stack
-  deriving (Eq, Read, Show, Generic)
-  deriving (Binary, Hashable, NFData)
-
-findGhcForBuildSystem :: BuildSystem -> FilePath -> IO FilePath
-findGhcForBuildSystem Cabal _cwd =
-    liftIO $ fromMaybe (error "ghc is not in the PATH") <$> findExecutable "ghc"
-findGhcForBuildSystem Stack cwd = do
-    Stdout ghcLoc <- cmd [Cwd cwd] ("stack exec which ghc" :: String)
-    return ghcLoc
-
-instance FromJSON BuildSystem where
-    parseJSON x = fromString . lower <$> parseJSON x
-      where
-        fromString "stack" = Stack
-        fromString "cabal" = Cabal
-        fromString other   = error $ "Unknown build system: " <> other
-
-instance ToJSON BuildSystem where
-    toJSON = toJSON . show
-
---------------------------------------------------------------------------------
-
-data GitCommit = GitCommit
-  { -- | A git hash, tag or branch name (e.g. v0.1.0)
-    gitName :: Text,
-    -- | A human understandable name (e.g. fix-collisions-leak)
-    name    :: Maybe Text,
-    -- | The human understandable name of the parent, if specified explicitly
-    parent  :: Maybe Text,
-    -- | Whether to include this version in the top chart
-    include :: Bool
-  }
-  deriving (Binary, Eq, Hashable, Generic, NFData, Show)
-
-instance FromJSON GitCommit where
-  parseJSON (String s) = pure $ GitCommit s Nothing Nothing True
-  parseJSON o@(Object _) = do
-    let keymap = o ^. _Object
-    case toList keymap of
-      [(name, String gitName)] -> pure $ GitCommit gitName (Just name) Nothing True
-      [(name, Object props)] ->
-        GitCommit
-          <$> props .:? "git"  .!= name
-          <*> pure (Just name)
-          <*> props .:? "parent"
-          <*> props .:? "include" .!= True
-      _ -> empty
-  parseJSON _ = empty
-
-instance ToJSON GitCommit where
-  toJSON GitCommit {..} =
-    case name of
-      Nothing -> String gitName
-      Just n  -> object [fromString (T.unpack n) .= String gitName]
-
-humanName :: GitCommit -> Text
-humanName GitCommit {..} = fromMaybe gitName name
-
-findPrev :: Text -> [GitCommit] -> Text
-findPrev name (x : y : xx)
-  | humanName y == name = humanName x
-  | otherwise = findPrev name (y : xx)
-findPrev name _ = name
-
---------------------------------------------------------------------------------
-
--- | A line in the output of -S
-data Frame = Frame
-  { allocated, copied, live            :: !Int,
-    user, elapsed, totUser, totElapsed :: !Double,
-    generation                         :: !Int
-  }
-  deriving (Show)
-
-instance Read Frame where
-  readPrec = do
-    spaces
-    allocated <- readPrec @Int <* spaces
-    copied <- readPrec @Int <* spaces
-    live <- readPrec @Int <* spaces
-    user <- readPrec @Double <* spaces
-    elapsed <- readPrec @Double <* spaces
-    totUser <- readPrec @Double <* spaces
-    totElapsed <- readPrec @Double <* spaces
-    _ <- readPrec @Int <* spaces
-    _ <- readPrec @Int <* spaces
-    "(Gen:  " <- replicateM 7 get
-    generation <- readPrec @Int
-    ')' <- get
-    return Frame {..}
-    where
-      spaces = readP_to_Prec $ const P.skipSpaces
-
--- | A file path containing the output of -S for a given run
-data RunLog = RunLog
-  { runVersion :: !String,
-    runFrames  :: ![Frame],
-    runSuccess :: !Bool
-  }
-
-loadRunLog :: HasCallStack => Escaped FilePath -> String -> Action RunLog
-loadRunLog (Escaped csv_fp) ver = do
-  let log_fp = replaceExtension csv_fp "gcStats.log"
-  log <- readFileLines log_fp
-  csv <- readFileLines csv_fp
-  let frames =
-        [ f
-          | l <- log,
-            Just f <- [readMaybe l],
-            -- filter out gen 0 events as there are too many
-            generation f == 1
-        ]
-      -- TODO this assumes a certain structure in the CSV file
-      success = case map (T.split (== ',') . T.pack) csv of
-          [_header, _name:s:_] | Just s <- readMaybe (T.unpack s) -> s
-          _ -> error $ "Cannot parse: " <> csv_fp
-  return $ RunLog ver frames success
-
---------------------------------------------------------------------------------
-
-data TraceMetric = Allocated | Copied | Live | User | Elapsed
-  deriving (Generic, Enum, Bounded, Read)
-
-instance Show TraceMetric where
-  show Allocated = "Allocated bytes"
-  show Copied    = "Copied bytes"
-  show Live      = "Live bytes"
-  show User      = "User time"
-  show Elapsed   = "Elapsed time"
-
-frameMetric :: TraceMetric -> Frame -> Double
-frameMetric Allocated = fromIntegral . allocated
-frameMetric Copied    = fromIntegral . copied
-frameMetric Live      = fromIntegral . live
-frameMetric Elapsed   = elapsed
-frameMetric User      = user
-
-data Diagram = Diagram
-  { traceMetric :: TraceMetric,
-    runLogs     :: [RunLog],
-    title       :: String
-  }
-  deriving (Generic)
-
-plotDiagram :: Bool -> Diagram -> FilePath -> Action ()
-plotDiagram includeFailed t@Diagram {traceMetric, runLogs} out = do
-  let extract = frameMetric traceMetric
-  liftIO $ E.toFile E.def out $ do
-    E.layout_title E..= title t
-    E.setColors myColors
-    forM_ runLogs $ \rl ->
-      when (includeFailed || runSuccess rl) $ E.plot $ do
-        lplot <- E.line
-            (runVersion rl ++ if runSuccess rl then "" else " (FAILED)")
-            [ [ (totElapsed f, extract f)
-                | f <- runFrames rl
-                ]
-            ]
-        return (lplot E.& E.plot_lines_style . E.line_width E.*~ 2)
-
---------------------------------------------------------------------------------
-
-newtype Escaped a = Escaped {escaped :: a}
-
-newtype Unescaped a = Unescaped {unescaped :: a}
-  deriving newtype (Show, FromJSON, ToJSON, Eq, NFData, Binary, Hashable)
-
-escapeExperiment :: Unescaped String -> Escaped String
-escapeExperiment = Escaped . map f . unescaped
-  where
-    f ' '   = '_'
-    f other = other
-
-unescapeExperiment :: Escaped String -> Unescaped String
-unescapeExperiment = Unescaped . map f . escaped
-  where
-    f '_'   = ' '
-    f other = other
-
---------------------------------------------------------------------------------
-
-(-/-) :: FilePattern -> FilePattern -> FilePattern
-a -/- b = a <> "/" <> b
-
-interleave :: [[a]] -> [a]
-interleave = concat . transpose
-
---------------------------------------------------------------------------------
-
-myColors :: [E.AlphaColour Double]
-myColors = map E.opaque
-  [ E.blue
-  , E.green
-  , E.red
-  , E.orange
-  , E.yellow
-  , E.violet
-  , E.black
-  , E.gold
-  , E.brown
-  , E.hotpink
-  , E.aliceblue
-  , E.aqua
-  , E.beige
-  , E.bisque
-  , E.blueviolet
-  , E.burlywood
-  , E.cadetblue
-  , E.chartreuse
-  , E.coral
-  , E.crimson
-  , E.darkblue
-  , E.darkgray
-  , E.darkgreen
-  , E.darkkhaki
-  , E.darkmagenta
-  , E.deeppink
-  , E.dodgerblue
-  , E.firebrick
-  , E.forestgreen
-  , E.fuchsia
-  , E.greenyellow
-  , E.lightsalmon
-  , E.seagreen
-  , E.olive
-  , E.sandybrown
-  , E.sienna
-  , E.peru
-  ]
-
-dummyHp :: String
-dummyHp =
-    "JOB \"ghcide\" \
-    \DATE \"Sun Jan 31 09:30 2021\" \
-    \SAMPLE_UNIT \"seconds\" \
-    \VALUE_UNIT \"bytes\" \
-    \BEGIN_SAMPLE 0.000000 \
-    \END_SAMPLE 0.000000"
+{-# LANGUAGE AllowAmbiguousTypes       #-}
+{-# LANGUAGE ApplicativeDo             #-}
+{-# LANGUAGE ConstraintKinds           #-}
+{-# LANGUAGE DeriveAnyClass            #-}
+{-# LANGUAGE DerivingStrategies        #-}
+{-# LANGUAGE DuplicateRecordFields     #-}
+{-# LANGUAGE ExistentialQuantification #-}
+{-# LANGUAGE OverloadedStrings         #-}
+{-# LANGUAGE RankNTypes                #-}
+{-# LANGUAGE TypeFamilies              #-}
+
+{- |
+    This module provides a bunch of Shake rules to build multiple revisions of a
+    project and analyse their performance.
+
+    It assumes a project bench suite composed of examples that runs a fixed set
+    of experiments on every example
+
+    Your code must implement all of the GetFoo oracles and the IsExample class,
+    instantiate the Shake rules, and probably 'want' a set of targets.
+
+    The results of the benchmarks and the analysis are recorded in the file
+    system, using the following structure:
+
+    <build-folder>
+    ├── binaries
+    │   └── <git-reference>
+    │        ├── ghc.path                         - path to ghc used to build the executable
+    │        └── <executable>                     - binary for this version
+    │        └── commitid                         - Git commit id for this reference
+    ├─ <example>
+    │   ├── results.csv                           - aggregated results for all the versions
+    │   └── <git-reference>
+    │       ├── <experiment>.gcStats.log          - RTS -s output
+    │       ├── <experiment>.csv                  - stats for the experiment
+    │       ├── <experiment>.svg                  - Graph of bytes over elapsed time
+    │       ├── <experiment>.diff.svg             - idem, including the previous version
+    │       ├── <experiment>.heap.svg             - Heap profile
+    │       ├── <experiment>.log                  - bench stdout
+    │       └── results.csv                       - results of all the experiments for the example
+    ├── results.csv        - aggregated results of all the experiments and versions
+    └── <experiment>.svg   - graph of bytes over elapsed time, for all the included versions
+
+   For diff graphs, the "previous version" is the preceding entry in the list of versions
+   in the config file. A possible improvement is to obtain this info via `git rev-list`.
+ -}
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
+module Development.Benchmark.Rules
+  (
+      buildRules, MkBuildRules(..),
+      benchRules, MkBenchRules(..), BenchProject(..), ProfilingMode(..),
+      csvRules,
+      svgRules,
+      heapProfileRules,
+      phonyRules,
+      allTargetsForExample,
+      GetExample(..), GetExamples(..),
+      IsExample(..), RuleResultForExample,
+      GetExperiments(..),
+      GetVersions(..),
+      GetCommitId(..),
+      GetBuildSystem(..),
+      BuildSystem(..), findGhcForBuildSystem,
+      Escaped(..), Unescaped(..), escapeExperiment, unescapeExperiment,
+      GitCommit
+
+  ) where
+
+import           Control.Applicative
+import           Control.Lens                              ((^.))
+import           Control.Monad
+import qualified Control.Monad.State                       as S
+import           Data.Aeson                                (FromJSON (..),
+                                                            ToJSON (..),
+                                                            Value (..), object,
+                                                            (.!=), (.:?), (.=))
+import           Data.Aeson.Lens                           (_Object)
+import           Data.Char                                 (isDigit)
+import           Data.List                                 (find, isInfixOf,
+                                                            stripPrefix,
+                                                            transpose)
+import           Data.List.Extra                           (lower)
+import           Data.Maybe                                (fromMaybe)
+import           Data.String                               (fromString)
+import           Data.Text                                 (Text)
+import qualified Data.Text                                 as T
+import           Development.Shake
+import           Development.Shake.Classes                 (Binary, Hashable,
+                                                            NFData, Typeable)
+import           GHC.Exts                                  (IsList (toList),
+                                                            fromList)
+import           GHC.Generics                              (Generic)
+import           GHC.Stack                                 (HasCallStack)
+import qualified Graphics.Rendering.Chart.Backend.Diagrams as E
+import qualified Graphics.Rendering.Chart.Easy             as E
+import           System.Directory                          (createDirectoryIfMissing,
+                                                            findExecutable,
+                                                            renameFile)
+import           System.FilePath
+import           System.Time.Extra                         (Seconds)
+import qualified Text.ParserCombinators.ReadP              as P
+import           Text.Printf
+import           Text.Read                                 (Read (..), get,
+                                                            readMaybe,
+                                                            readP_to_Prec)
+
+newtype GetExperiments = GetExperiments () deriving newtype (Binary, Eq, Hashable, NFData, Show)
+newtype GetVersions = GetVersions () deriving newtype (Binary, Eq, Hashable, NFData, Show)
+newtype GetParent = GetParent Text deriving newtype (Binary, Eq, Hashable, NFData, Show)
+newtype GetCommitId = GetCommitId String deriving newtype (Binary, Eq, Hashable, NFData, Show)
+newtype GetBuildSystem = GetBuildSystem () deriving newtype (Binary, Eq, Hashable, NFData, Show)
+newtype GetExample = GetExample String deriving newtype (Binary, Eq, Hashable, NFData, Show)
+newtype GetExamples = GetExamples () deriving newtype (Binary, Eq, Hashable, NFData, Show)
+
+type instance RuleResult GetExperiments = [Unescaped String]
+type instance RuleResult GetVersions = [GitCommit]
+type instance RuleResult GetParent = Text
+type instance RuleResult GetCommitId = String
+type instance RuleResult GetBuildSystem = BuildSystem
+
+type RuleResultForExample e =
+    ( RuleResult GetExample ~ Maybe e
+    , RuleResult GetExamples ~ [e]
+    , IsExample e)
+
+-- | Knowledge needed to run an example
+class (Binary e, Eq e, Hashable e, NFData e, Show e, Typeable e) => IsExample e where
+    getExampleName :: e -> String
+
+--------------------------------------------------------------------------------
+
+allTargetsForExample :: IsExample e => ProfilingMode -> FilePath -> e -> Action [FilePath]
+allTargetsForExample prof baseFolder ex = do
+    experiments <- askOracle $ GetExperiments ()
+    versions    <- askOracle $ GetVersions ()
+    let buildFolder = baseFolder </> profilingPath prof
+    return $
+        [buildFolder </> getExampleName ex </> "results.csv"]
+        ++ [ buildFolder </> getExampleName ex </> escaped (escapeExperiment e) <.> "svg"
+             | e <- experiments
+           ]
+        ++ [ buildFolder </>
+             getExampleName ex </>
+             T.unpack (humanName ver) </>
+             escaped (escapeExperiment e) <.> mode
+             | e <- experiments,
+               ver <- versions,
+               mode <- ["svg", "diff.svg"] ++ ["heap.svg" | prof /= NoProfiling]
+           ]
+
+allBinaries :: FilePath -> String -> Action [FilePath]
+allBinaries buildFolder executableName = do
+    versions <- askOracle $ GetVersions ()
+    return $
+        [ buildFolder </> "binaries" </> T.unpack (humanName ver) </> executableName
+        | ver <- versions]
+
+-- | Generate a set of phony rules:
+--     * <prefix>all
+--     * <prefix><example>  for each example
+phonyRules
+    :: (Traversable t, IsExample e)
+    => String         -- ^ prefix
+    -> String         -- ^ Executable name
+    -> ProfilingMode
+    -> FilePath
+    -> t e
+    -> Rules ()
+phonyRules prefix executableName prof buildFolder examples = do
+    forM_ examples $ \ex ->
+        phony (prefix <> getExampleName ex) $ need =<<
+            allTargetsForExample prof buildFolder ex
+    phony (prefix <> "all") $ do
+        exampleTargets <- forM examples $ \ex ->
+            allTargetsForExample prof buildFolder ex
+        need $ (buildFolder </> profilingPath prof </> "results.csv")
+             : concat exampleTargets
+    phony (prefix <> "all-binaries") $ need =<< allBinaries buildFolder executableName
+--------------------------------------------------------------------------------
+type OutputFolder = FilePath
+
+data MkBuildRules buildSystem = MkBuildRules
+  { -- | Return the path to the GHC executable to use for the project found in the cwd
+    findGhc            :: buildSystem -> FilePath -> IO FilePath
+    -- | Name of the binary produced by 'buildProject'
+  , executableName     :: String
+    -- | An action that captures the source dependencies, used for the HEAD build
+  , projectDepends     :: Action ()
+    -- | Build the project found in the cwd and save the build artifacts in the output folder
+  , buildProject       :: buildSystem
+                       -> [CmdOption]
+                       -> OutputFolder
+                       -> Action ()
+  }
+
+-- | Rules that drive a build system to build various revisions of a project
+buildRules :: FilePattern -> MkBuildRules BuildSystem -> Rules ()
+-- TODO generalize BuildSystem
+buildRules build MkBuildRules{..} = do
+  -- query git for the commitid for a version
+  build -/- "binaries/*/commitid" %> \out -> do
+      alwaysRerun
+
+      let [_,_,ver,_] = splitDirectories out
+      mbEntry <- find ((== T.pack ver) . humanName) <$> askOracle (GetVersions ())
+      let gitThing :: String
+          gitThing = maybe ver (T.unpack . gitName) mbEntry
+      Stdout commitid <- command [] "git" ["rev-list", "-n", "1", gitThing]
+      writeFileChanged out $ init commitid
+
+  -- build rules for HEAD
+  priority 10 $ [ build -/- "binaries/HEAD/" <> executableName
+                , build -/- "binaries/HEAD/ghc.path"
+                ]
+    &%> \[out, ghcpath] -> do
+      projectDepends
+      liftIO $ createDirectoryIfMissing True $ dropFileName out
+      buildSystem <- askOracle $ GetBuildSystem ()
+      buildProject buildSystem [Cwd "."] (takeDirectory out)
+      ghcLoc <- liftIO $ findGhc buildSystem "."
+      writeFile' ghcpath ghcLoc
+
+  -- build rules for non HEAD revisions
+  [build -/- "binaries/*/" <> executableName
+   ,build -/- "binaries/*/ghc.path"
+   ] &%> \[out, ghcPath] -> do
+      let [_, _binaries, ver, _] = splitDirectories out
+      liftIO $ createDirectoryIfMissing True $ dropFileName out
+      commitid <- readFile' $ takeDirectory out </> "commitid"
+      cmd_ $ "git worktree add bench-temp-" ++ ver ++ " " ++ commitid
+      buildSystem <- askOracle $ GetBuildSystem ()
+      flip actionFinally (cmd_ ("git worktree remove bench-temp-" <> ver <> " --force" :: String)) $ do
+        ghcLoc <- liftIO $ findGhc buildSystem ver
+        buildProject buildSystem [Cwd $ "bench-temp-" <> ver] (".." </> takeDirectory out)
+        writeFile' ghcPath ghcLoc
+
+--------------------------------------------------------------------------------
+data MkBenchRules buildSystem example =  forall setup. MkBenchRules
+  {
+  -- | Workaround for Shake not allowing to call 'askOracle' from 'benchProject
+    setupProject :: Action setup
+  -- | An action that invokes the executable to run the benchmark
+  , benchProject :: setup -> buildSystem -> [CmdOption] -> BenchProject example -> Action ()
+  -- | An action that performs any necessary warmup. Will only be invoked once
+  , warmupProject :: buildSystem -> FilePath -> [CmdOption] -> example -> Action ()
+  -- | Name of the executable to benchmark. Should match the one used to 'MkBuildRules'
+  , executableName :: String
+  }
+
+data BenchProject example = BenchProject
+    { outcsv       :: FilePath         -- ^ where to save the CSV output
+    , exePath      :: FilePath         -- ^ where to find the executable for benchmarking
+    , exeExtraArgs :: [String]         -- ^ extra args for the executable
+    , example      :: example          -- ^ example to benchmark
+    , experiment   :: Escaped String   -- ^ experiment to run
+    }
+
+data ProfilingMode = NoProfiling | CheapHeapProfiling Seconds
+    deriving (Eq)
+
+profilingP :: String -> Maybe ProfilingMode
+profilingP "unprofiled" = Just NoProfiling
+profilingP inp | Just delay <- stripPrefix "profiled-" inp, Just i <- readMaybe delay = Just $ CheapHeapProfiling i
+profilingP _ = Nothing
+
+profilingPath :: ProfilingMode -> FilePath
+profilingPath NoProfiling            = "unprofiled"
+profilingPath (CheapHeapProfiling i) = "profiled-" <> show i
+
+-- TODO generalize BuildSystem
+benchRules :: RuleResultForExample example => FilePattern -> MkBenchRules BuildSystem example -> Rules ()
+benchRules build MkBenchRules{..} = do
+
+  benchResource <- newResource "ghcide-bench" 1
+  -- warmup an example
+  build -/- "binaries/*/*.warmup" %> \out -> do
+        let [_, _, ver, exampleName] = splitDirectories (dropExtension out)
+        let exePath = build </> "binaries" </> ver </> executableName
+            ghcPath = build </> "binaries" </> ver </> "ghc.path"
+        need [exePath, ghcPath]
+        buildSystem <- askOracle  $ GetBuildSystem ()
+        example <- fromMaybe (error $ "Unknown example " <> exampleName)
+                    <$> askOracle (GetExample exampleName)
+        let exeExtraArgs = []
+            outcsv = ""
+            experiment = Escaped "hover"
+        withResource benchResource 1 $ warmupProject buildSystem exePath
+              [ EchoStdout False,
+                FileStdout out,
+                RemEnv "NIX_GHC_LIBDIR",
+                RemEnv "GHC_PACKAGE_PATH",
+                AddPath [takeDirectory ghcPath, "."] []
+              ]
+              example
+  -- run an experiment
+  priority 0 $
+    [ build -/- "*/*/*/*.csv",
+      build -/- "*/*/*/*.gcStats.log",
+      build -/- "*/*/*/*.output.log",
+      build -/- "*/*/*/*.eventlog",
+      build -/- "*/*/*/*.hp"
+    ] &%> \[outcsv, outGc, outLog, outEventlog, outHp] -> do
+        let [_, flavour, exampleName, ver, exp] = splitDirectories outcsv
+            prof = fromMaybe (error $ "Not a valid profiling mode: " <> flavour) $ profilingP flavour
+        example <- fromMaybe (error $ "Unknown example " <> exampleName)
+                    <$> askOracle (GetExample exampleName)
+        buildSystem <- askOracle  $ GetBuildSystem ()
+        setupRes    <- setupProject
+        liftIO $ createDirectoryIfMissing True $ dropFileName outcsv
+        let exePath    = build </> "binaries" </> ver </> executableName
+            exeExtraArgs =
+                [ "+RTS"
+                , "-l"
+                , "-S" <> outGc]
+             ++ concat
+                [[ "-h"
+                  , "-i" <> show i
+                  , "-qg"]
+                 | CheapHeapProfiling i <- [prof]]
+             ++ ["-RTS"]
+            ghcPath    = build </> "binaries" </> ver </> "ghc.path"
+            warmupPath = build </> "binaries" </> ver </> exampleName <.> "warmup"
+            experiment = Escaped $ dropExtension exp
+        need [exePath, ghcPath, warmupPath]
+        ghcPath <- readFile' ghcPath
+        withResource benchResource 1 $ do
+          benchProject setupRes buildSystem
+              [ EchoStdout False,
+                FileStdout outLog,
+                RemEnv "NIX_GHC_LIBDIR",
+                RemEnv "GHC_PACKAGE_PATH",
+                AddPath [takeDirectory ghcPath, "."] []
+              ]
+              BenchProject {..}
+        liftIO $ renameFile "ghcide.eventlog" outEventlog
+        liftIO $ case prof of
+            CheapHeapProfiling{} -> renameFile "ghcide.hp" outHp
+            NoProfiling          -> writeFile outHp dummyHp
+
+        -- extend csv output with allocation data
+        csvContents <- liftIO $ lines <$> readFile outcsv
+        let header = head csvContents
+            results = tail csvContents
+            header' = header <> ", maxResidency, allocatedBytes"
+        results' <- forM results $ \row -> do
+            (maxResidency, allocations) <- liftIO
+                    (parseMaxResidencyAndAllocations <$> readFile outGc)
+            return $ printf "%s, %s, %s" row (showMB maxResidency) (showMB allocations)
+        let csvContents' = header' : results'
+        writeFileLines outcsv csvContents'
+    where
+        showMB :: Int -> String
+        showMB x = show (x `div` 2^(20::Int)) <> "MB"
+
+-- Parse the max residency and allocations in RTS -s output
+parseMaxResidencyAndAllocations :: String -> (Int, Int)
+parseMaxResidencyAndAllocations input =
+    (f "maximum residency", f "bytes allocated in the heap")
+  where
+    inps = reverse $ lines input
+    f label = case find (label `isInfixOf`) inps of
+        Just l  -> read $ filter isDigit $ head $ words l
+        Nothing -> -1
+
+
+--------------------------------------------------------------------------------
+
+-- | Rules to aggregate the CSV output of individual experiments
+csvRules :: forall example . RuleResultForExample example => FilePattern -> Rules ()
+csvRules build = do
+  -- build results for every experiment*example
+  build -/- "*/*/*/results.csv" %> \out -> do
+      experiments <- askOracle $ GetExperiments ()
+
+      let allResultFiles = [takeDirectory out </> escaped (escapeExperiment e) <.> "csv" | e <- experiments]
+      allResults <- traverse readFileLines allResultFiles
+
+      let header = head $ head allResults
+          results = map tail allResults
+      writeFileChanged out $ unlines $ header : concat results
+
+  -- aggregate all experiments for an example
+  build -/- "*/*/results.csv" %> \out -> do
+    versions <- map (T.unpack . humanName) <$> askOracle (GetVersions ())
+    let allResultFiles = [takeDirectory out </> v </> "results.csv" | v <- versions]
+
+    allResults <- traverse readFileLines allResultFiles
+
+    let header = head $ head allResults
+        results = map tail allResults
+        header' = "version, " <> header
+        results' = zipWith (\v -> map (\l -> v <> ", " <> l)) versions results
+
+    writeFileChanged out $ unlines $ header' : interleave results'
+
+  -- aggregate all examples
+  build -/- "*/results.csv" %> \out -> do
+    examples <- map (getExampleName @example) <$> askOracle (GetExamples ())
+    let allResultFiles = [takeDirectory out </> e </> "results.csv" | e <- examples]
+
+    allResults <- traverse readFileLines allResultFiles
+
+    let header = head $ head allResults
+        results = map tail allResults
+        header' = "example, " <> header
+        results' = zipWith (\e -> map (\l -> e <> ", " <> l)) examples results
+
+    writeFileChanged out $ unlines $ header' : concat results'
+
+--------------------------------------------------------------------------------
+
+-- | Rules to produce charts for the GC stats
+svgRules :: FilePattern -> Rules ()
+svgRules build = do
+  void $ addOracle $ \(GetParent name) -> findPrev name <$> askOracle (GetVersions ())
+  -- chart GC stats for an experiment on a given revision
+  priority 1 $
+    build -/- "*/*/*/*.svg" %> \out -> do
+      let [_, _, _example, ver, _exp] = splitDirectories out
+      runLog <- loadRunLog (Escaped $ replaceExtension out "csv") ver
+      let diagram = Diagram Live [runLog] title
+          title = ver <> " live bytes over time"
+      plotDiagram True diagram out
+
+  -- chart of GC stats for an experiment on this and the previous revision
+  priority 2 $
+    build -/- "*/*/*/*.diff.svg" %> \out -> do
+      let [b, flav, example, ver, exp_] = splitDirectories out
+          exp = Escaped $ dropExtension2 exp_
+      prev <- fmap T.unpack $ askOracle $ GetParent $ T.pack ver
+
+      runLog <- loadRunLog (Escaped $ replaceExtension (dropExtension out) "csv") ver
+      runLogPrev <- loadRunLog (Escaped $ joinPath [b,flav, example, prev, replaceExtension (dropExtension exp_) "csv"]) prev
+
+      let diagram = Diagram Live [runLog, runLogPrev] title
+          title = show (unescapeExperiment exp) <> " - live bytes over time compared"
+      plotDiagram True diagram out
+
+  -- aggregated chart of GC stats for all the revisions
+  build -/- "*/*/*.svg" %> \out -> do
+    let exp = Escaped $ dropExtension $ takeFileName out
+    versions <- askOracle $ GetVersions ()
+
+    runLogs <- forM (filter include versions) $ \v -> do
+      let v' = T.unpack (humanName v)
+      loadRunLog (Escaped $ takeDirectory out </> v' </> replaceExtension (takeFileName out) "csv") v'
+
+    let diagram = Diagram Live runLogs title
+        title = show (unescapeExperiment exp) <> " - live bytes over time"
+    plotDiagram False diagram out
+
+heapProfileRules :: FilePattern -> Rules ()
+heapProfileRules build = do
+  priority 3 $
+    build -/- "*/*/*/*.heap.svg" %> \out -> do
+      let hpFile = dropExtension2 out <.> "hp"
+      need [hpFile]
+      cmd_ ("hp2pretty" :: String) [hpFile]
+      liftIO $ renameFile (dropExtension hpFile <.> "svg") out
+
+dropExtension2 :: FilePath -> FilePath
+dropExtension2 = dropExtension . dropExtension
+--------------------------------------------------------------------------------
+--------------------------------------------------------------------------------
+
+-- | Default build system that handles Cabal and Stack
+data BuildSystem = Cabal | Stack
+  deriving (Eq, Read, Show, Generic)
+  deriving (Binary, Hashable, NFData)
+
+findGhcForBuildSystem :: BuildSystem -> FilePath -> IO FilePath
+findGhcForBuildSystem Cabal _cwd =
+    liftIO $ fromMaybe (error "ghc is not in the PATH") <$> findExecutable "ghc"
+findGhcForBuildSystem Stack cwd = do
+    Stdout ghcLoc <- cmd [Cwd cwd] ("stack exec which ghc" :: String)
+    return ghcLoc
+
+instance FromJSON BuildSystem where
+    parseJSON x = fromString . lower <$> parseJSON x
+      where
+        fromString "stack" = Stack
+        fromString "cabal" = Cabal
+        fromString other   = error $ "Unknown build system: " <> other
+
+instance ToJSON BuildSystem where
+    toJSON = toJSON . show
+
+--------------------------------------------------------------------------------
+
+data GitCommit = GitCommit
+  { -- | A git hash, tag or branch name (e.g. v0.1.0)
+    gitName :: Text,
+    -- | A human understandable name (e.g. fix-collisions-leak)
+    name    :: Maybe Text,
+    -- | The human understandable name of the parent, if specified explicitly
+    parent  :: Maybe Text,
+    -- | Whether to include this version in the top chart
+    include :: Bool
+  }
+  deriving (Binary, Eq, Hashable, Generic, NFData, Show)
+
+instance FromJSON GitCommit where
+  parseJSON (String s) = pure $ GitCommit s Nothing Nothing True
+  parseJSON o@(Object _) = do
+    let keymap = o ^. _Object
+    case toList keymap of
+      [(name, String gitName)] -> pure $ GitCommit gitName (Just name) Nothing True
+      [(name, Object props)] ->
+        GitCommit
+          <$> props .:? "git"  .!= name
+          <*> pure (Just name)
+          <*> props .:? "parent"
+          <*> props .:? "include" .!= True
+      _ -> empty
+  parseJSON _ = empty
+
+instance ToJSON GitCommit where
+  toJSON GitCommit {..} =
+    case name of
+      Nothing -> String gitName
+      Just n  -> object [fromString (T.unpack n) .= String gitName]
+
+humanName :: GitCommit -> Text
+humanName GitCommit {..} = fromMaybe gitName name
+
+findPrev :: Text -> [GitCommit] -> Text
+findPrev name (x : y : xx)
+  | humanName y == name = humanName x
+  | otherwise = findPrev name (y : xx)
+findPrev name _ = name
+
+--------------------------------------------------------------------------------
+
+-- | A line in the output of -S
+data Frame = Frame
+  { allocated, copied, live            :: !Int,
+    user, elapsed, totUser, totElapsed :: !Double,
+    generation                         :: !Int
+  }
+  deriving (Show)
+
+instance Read Frame where
+  readPrec = do
+    spaces
+    allocated <- readPrec @Int <* spaces
+    copied <- readPrec @Int <* spaces
+    live <- readPrec @Int <* spaces
+    user <- readPrec @Double <* spaces
+    elapsed <- readPrec @Double <* spaces
+    totUser <- readPrec @Double <* spaces
+    totElapsed <- readPrec @Double <* spaces
+    _ <- readPrec @Int <* spaces
+    _ <- readPrec @Int <* spaces
+    "(Gen:  " <- replicateM 7 get
+    generation <- readPrec @Int
+    ')' <- get
+    return Frame {..}
+    where
+      spaces = readP_to_Prec $ const P.skipSpaces
+
+-- | A file path containing the output of -S for a given run
+data RunLog = RunLog
+  { runVersion :: !String,
+    runFrames  :: ![Frame],
+    runSuccess :: !Bool,
+    runFirstReponse :: !(Maybe Seconds)
+  }
+
+loadRunLog :: HasCallStack => Escaped FilePath -> String -> Action RunLog
+loadRunLog (Escaped csv_fp) ver = do
+  let log_fp = replaceExtension csv_fp "gcStats.log"
+  log <- readFileLines log_fp
+  csv <- readFileLines csv_fp
+  let frames =
+        [ f
+          | l <- log,
+            Just f <- [readMaybe l],
+            -- filter out gen 0 events as there are too many
+            generation f == 1
+        ]
+      -- TODO this assumes a certain structure in the CSV file
+      (success, firstResponse) = case map (map T.strip . T.split (== ',') . T.pack) csv of
+          [header, row]
+            | let table = zip header row
+                  timeForFirstResponse :: Maybe Seconds
+                  timeForFirstResponse = readMaybe . T.unpack =<< lookup "firstBuildTime" table
+            , Just s <- lookup "success" table
+            , Just s <- readMaybe (T.unpack s)
+            -> (s,timeForFirstResponse)
+          _ -> error $ "Cannot parse: " <> csv_fp
+  return $ RunLog ver frames success firstResponse
+
+--------------------------------------------------------------------------------
+
+data TraceMetric = Allocated | Copied | Live | User | Elapsed
+  deriving (Generic, Enum, Bounded, Read)
+
+instance Show TraceMetric where
+  show Allocated = "Allocated bytes"
+  show Copied    = "Copied bytes"
+  show Live      = "Live bytes"
+  show User      = "User time"
+  show Elapsed   = "Elapsed time"
+
+frameMetric :: TraceMetric -> Frame -> Double
+frameMetric Allocated = fromIntegral . allocated
+frameMetric Copied    = fromIntegral . copied
+frameMetric Live      = fromIntegral . live
+frameMetric Elapsed   = elapsed
+frameMetric User      = user
+
+data Diagram = Diagram
+  { traceMetric :: TraceMetric,
+    runLogs     :: [RunLog],
+    title       :: String
+  }
+  deriving (Generic)
+
+plotDiagram :: Bool -> Diagram -> FilePath -> Action ()
+plotDiagram includeFailed t@Diagram {traceMetric, runLogs} out = do
+  let extract = frameMetric traceMetric
+  liftIO $ E.toFile E.def out $ do
+    E.layout_title E..= title t
+    E.setColors myColors
+    forM_ runLogs $ \rl ->
+      when (includeFailed || runSuccess rl) $ do
+        -- Get the color we are going to use
+        ~(c:_) <- E.liftCState $ S.gets (E.view E.colors)
+        E.plot $ do
+          lplot <- E.line
+              (runVersion rl ++ if runSuccess rl then "" else " (FAILED)")
+              [ [ (totElapsed f, extract f)
+                  | f <- runFrames rl
+                  ]
+              ]
+          return (lplot E.& E.plot_lines_style . E.line_width E.*~ 2)
+        case (runFirstReponse rl) of
+          Just t -> E.plot $ pure $
+              E.vlinePlot ("First build: " ++ runVersion rl) (E.defaultPlotLineStyle E.& E.line_color E..~ c) t
+          _ -> pure ()
+
+--------------------------------------------------------------------------------
+
+newtype Escaped a = Escaped {escaped :: a}
+
+newtype Unescaped a = Unescaped {unescaped :: a}
+  deriving newtype (Show, FromJSON, ToJSON, Eq, NFData, Binary, Hashable)
+
+escapeExperiment :: Unescaped String -> Escaped String
+escapeExperiment = Escaped . map f . unescaped
+  where
+    f ' '   = '_'
+    f other = other
+
+unescapeExperiment :: Escaped String -> Unescaped String
+unescapeExperiment = Unescaped . map f . escaped
+  where
+    f '_'   = ' '
+    f other = other
+
+--------------------------------------------------------------------------------
+
+(-/-) :: FilePattern -> FilePattern -> FilePattern
+a -/- b = a <> "/" <> b
+
+interleave :: [[a]] -> [a]
+interleave = concat . transpose
+
+--------------------------------------------------------------------------------
+
+myColors :: [E.AlphaColour Double]
+myColors = map E.opaque
+  [ E.blue
+  , E.green
+  , E.red
+  , E.orange
+  , E.yellow
+  , E.violet
+  , E.black
+  , E.gold
+  , E.brown
+  , E.hotpink
+  , E.aliceblue
+  , E.aqua
+  , E.beige
+  , E.bisque
+  , E.blueviolet
+  , E.burlywood
+  , E.cadetblue
+  , E.chartreuse
+  , E.coral
+  , E.crimson
+  , E.darkblue
+  , E.darkgray
+  , E.darkgreen
+  , E.darkkhaki
+  , E.darkmagenta
+  , E.deeppink
+  , E.dodgerblue
+  , E.firebrick
+  , E.forestgreen
+  , E.fuchsia
+  , E.greenyellow
+  , E.lightsalmon
+  , E.seagreen
+  , E.olive
+  , E.sandybrown
+  , E.sienna
+  , E.peru
+  ]
+
+dummyHp :: String
+dummyHp =
+    "JOB \"ghcide\" \
+    \DATE \"Sun Jan 31 09:30 2021\" \
+    \SAMPLE_UNIT \"seconds\" \
+    \VALUE_UNIT \"bytes\" \
+    \BEGIN_SAMPLE 0.000000 \
+    \END_SAMPLE 0.000000"
