Bump version to 0.1.16.2

This reverts commit 300cfd3ba6.

.gitlab/script/ghcup_version.sh

@@ -116,7 +116,20 @@ else
 	if [ "${OS}" = "LINUX" ] ; then
 		eghcup --downloader=wget prefetch ghc 8.10.3
 		eghcup --offline install ghc 8.10.3
-	else # test wget a bit
+		if [ "${ARCH}" = "64" ] ; then
+			expected=$(cat "$( cd "$(dirname "$0")" ; pwd -P )/../ghc-8.10.3-linux.files" | sort)
+			actual=$(cd "${GHCUP_DIR}/ghc/8.10.3/" && find | sort)
+			[ "${actual}" = "${expected}" ]
+			unset actual expected
+		fi
+	elif [ "${OS}" = "WINDOWS" ] ; then
+		eghcup prefetch ghc 8.10.3
+		eghcup --offline install ghc 8.10.3
+		expected=$(cat "$( cd "$(dirname "$0")" ; pwd -P )/../ghc-8.10.3-windows.files" | sort)
+		actual=$(cd "${GHCUP_DIR}/ghc/8.10.3/" && find | sort)
+		[ "${actual}" = "${expected}" ]
+		unset actual expected
+	else
 		eghcup prefetch ghc 8.10.3
 		eghcup --offline install ghc 8.10.3
 	fi
@@ -196,6 +209,21 @@ sha3=$(sha_sum "${GHCUP_DIR}/cache/ghcup-${JSON_VERSION}.yaml")
 [ "${etag2}" = "${etag3}" ]
 [ "${sha2}" = "${sha3}" ]
 
+# test isolated installs
+eghcup install ghc -i "$(pwd)/isolated" 8.10.5
+[ "$(isolated/bin/ghc --numeric-version)" = "8.10.5" ]
+! eghcup install ghc -i "$(pwd)/isolated" 8.10.5
+if [ "${ARCH}" = "64" ] ; then
+	if [ "${OS}" = "LINUX" ] || [ "${OS}" = "WINDOWS" ] ; then
+		eghcup install cabal -i "$(pwd)/isolated" 3.4.0.0
+		[ "$(isolated/cabal --numeric-version)" = "3.4.0.0" ]
+		eghcup install stack -i "$(pwd)/isolated" 2.7.3
+		[ "$(isolated/stack --numeric-version)" = "2.7.3" ]
+		eghcup install hls -i "$(pwd)/isolated" 1.3.0
+		[ "$(isolated/haskell-language-server-wrapper --numeric-version)" = "1.3.0" ] ||
+			[ "$(isolated/haskell-language-server-wrapper --numeric-version)" = "1.3.0.0" ]
+	fi
+fi
 
 eghcup upgrade
 eghcup upgrade -f

CHANGELOG.md

@@ -1,5 +1,14 @@
 # Revision history for ghcup
 
+## 0.1.16.2 -- 2021-08-12
+
+* Add isolated installations wrt [#141](https://gitlab.haskell.org/haskell/ghcup-hs/-/merge_requests/141) by Arjun Kathuria
+* Implement config cli MVP wrt [#134](https://gitlab.haskell.org/haskell/ghcup-hs/-/merge_requests/134) by Oleksii Dorozhkin
+* Fix `ghcup compile ghc --flavor`
+* Fix minor installation bug causing increased disk space wrt [#139](https://gitlab.haskell.org/haskell/ghcup-hs/-/merge_requests/139)
+* Improved error handling wrt [#136](https://gitlab.haskell.org/haskell/ghcup-hs/-/merge_requests/136)
+* Various improvements to metadata download when using `file://` and `--offline` wrt [#137](https://gitlab.haskell.org/haskell/ghcup-hs/-/merge_requests/137)
+
 ## 0.1.16.1 -- 2021-07-29
 
 * Add 'nuke' subcommand wrt [#135](https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/135), implemented by Arjun Kathuria

README.md

@@ -19,8 +19,6 @@ Similar in scope to [rustup](https://github.com/rust-lang-nursery/rustup.rs), [p
      * [Env variables](#env-variables)
      * [Installing custom bindists](#installing-custom-bindists)
      * [Tips and tricks](#tips-and-tricks)
-     * [Stack hooks](#stack-hooks)
-     * [Sharing MSys2 between stack and ghcup](#sharing-msys2-between-stack-and-ghcup)
    * [Design goals](#design-goals)
    * [How](#how)
    * [Known users](#known-users)
@@ -141,10 +139,6 @@ This is the complete list of env variables that change GHCup behavior:
 * `GHCUP_SKIP_UPDATE_CHECK`: Skip the (possibly annoying) update check when you run a command
 * `CC`/`LD` etc.: full environment is passed to the build system when compiling GHC via GHCup
 
-On windows, there are additional variables:
-
-* `GHCUP_MSYS2`: where to find msys2, so we can invoke shells and other cool stuff
-
 ### Installing custom bindists
 
 There are a couple of good use cases to install custom bindists:
@@ -208,36 +202,6 @@ with_ghc 8.10.5 code path/to/haskell/source
 Cabal and HLS will now see `8.10.5` as the primary GHC, without the need to
 run `ghcup set` all the time when switching between projects.
 
-### Stack hooks
-
-GHCup distributes a patched Stack, which has support for custom installation hooks, see:
-
-* https://github.com/commercialhaskell/stack/pull/5585
-
-Usually, the bootstrap script will already install a hook for you. If not,
-download it [here](https://gitlab.haskell.org/haskell/ghcup-hs/-/tree/master/hooks/stack/ghc-install.sh),
-place it in `~/.stack/hooks/ghc-install.sh` and make sure it's executable.
-
-Hooks aren't run when `system-ghc: true` is set in `stack.yaml`. If you want stack
-to never fall back to its own installation logic if ghcup fails, run the following command:
-
-```sh
-stack config set install-ghc false --global
-```
-
-### Sharing MSys2 between stack and ghcup
-
-You can tell stack to use GHCup's MSys2 installation. Add the following lines to `~/.stack/config.yaml`:
-
-```yml
-skip-msys: true
-extra-path:
-  - "C:\\ghcup\\msys64\\usr\\bin"
-  - "C:\\ghcup\\msys64\\mingw64\\bin"
-extra-include-dirs: "C:\\ghcup\\msys64\\mingw64\\include"
-extra-lib-dirs: "C:\\ghcup\\msys64\\mingw64\\lib"
-```
-
 ## Design goals
 
 1. simplicity
@@ -314,6 +278,18 @@ to figure out whether you have the correct toolchain and
 the correct dependencies. Refer to [the official docs](https://ghc.haskell.org/trac/ghc/wiki/Building/Preparation/Linux)
 on how to prepare your environment for building GHC.
 
+### Stack support
+
+There may be a number of bugs when trying to make ghcup installed GHC versions work with stack,
+such as:
+
+- https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/188
+
+Further, stack's upgrade procedure may break/confuse ghcup. There are a number of integration
+issues discussed here:
+
+- https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/153
+
 ### Windows support
 
 Windows support is in early stages. Since windows doesn't support symbolic links properly,

app/ghcup-gen/Validate.hs

@@ -237,7 +237,7 @@ validateTarballs (TarballFilter etool versionRegex) dls gt = do
                   ($(logError) $ T.pack $ prettyShow e)
                 liftIO $ exitWith (ExitFailure 2)
 
-    let appstate = AppState (Settings True False Never Curl False GHCupURL False) dirs defaultKeyBindings (GHCupInfo mempty mempty mempty) pfreq
+    let appstate = AppState (Settings True False Never Curl True GHCupURL False) dirs defaultKeyBindings (GHCupInfo mempty mempty mempty) pfreq
 
     r <-
       runLogger

app/ghcup/BrickMain.hs

@@ -440,27 +440,29 @@ install' _ (_, ListResult {..}) = do
               , TagNotFound
               , DigestError
               , DownloadFailed
+              , DirNotEmpty
               , NoUpdate
               , TarDirDoesNotExist
+              , FileAlreadyExistsError
               ]
 
   run (do
       case lTool of
         GHC   -> do
           let vi = getVersionInfo lVer GHC dls
-          liftE $ installGHCBin lVer $> vi
+          liftE $ installGHCBin lVer Nothing $> vi
         Cabal -> do
           let vi = getVersionInfo lVer Cabal dls
-          liftE $ installCabalBin lVer $> vi
+          liftE $ installCabalBin lVer Nothing $> vi
         GHCup -> do
           let vi = snd <$> getLatest dls GHCup
           liftE $ upgradeGHCup Nothing False $> vi
         HLS   -> do
           let vi = getVersionInfo lVer HLS dls
-          liftE $ installHLSBin lVer $> vi
+          liftE $ installHLSBin lVer Nothing $> vi
         Stack -> do
           let vi = getVersionInfo lVer Stack dls
-          liftE $ installStackBin lVer $> vi
+          liftE $ installStackBin lVer Nothing $> vi
     )
     >>= \case
           VRight vi                         -> do

app/ghcup/Main.hs

@@ -78,6 +78,8 @@ import qualified Data.Map.Strict               as M
 import qualified Data.Text                     as T
 import qualified Data.Text.IO                  as T
 import qualified Data.Text.Encoding            as E
+import qualified Data.Yaml                     as Y
+import qualified Data.Yaml.Pretty              as YP
 import qualified Text.Megaparsec               as MP
 import qualified Text.Megaparsec.Char          as MPC
 
@@ -105,6 +107,7 @@ data Command
   | Rm (Either RmCommand RmOptions)
   | DInfo
   | Compile CompileCommand
+  | Config ConfigCommand
   | Whereis WhereisOptions WhereisCommand
   | Upgrade UpgradeOpts Bool
   | ToolRequirements
@@ -138,6 +141,7 @@ data InstallOptions = InstallOptions
   , instPlatform :: Maybe PlatformRequest
   , instBindist  :: Maybe URI
   , instSet      :: Bool
+  , isolateDir   :: Maybe FilePath
   }
 
 data SetCommand = SetGHC SetOptions
@@ -173,6 +177,8 @@ data RmOptions = RmOptions
 
 data CompileCommand = CompileGHC GHCCompileOptions
 
+data ConfigCommand = ShowConfig | SetConfig String String | InitConfig
+
 data GHCCompileOptions = GHCCompileOptions
   { targetGhc    :: Either Version GitBranch
   , bootstrapGhc :: Either Version FilePath
@@ -185,6 +191,7 @@ data GHCCompileOptions = GHCCompileOptions
   , ovewrwiteVer :: Maybe Version
   , buildFlavour :: Maybe String
   , hadrian      :: Bool
+  , isolateDir   :: Maybe FilePath
   }
 
 data UpgradeOpts = UpgradeInplace
@@ -408,6 +415,12 @@ com =
                   <> footerDoc (Just $ text changeLogFooter)
                   )
                )
+          <> command
+               "config"
+               (   Config
+               <$> info (configP <**> helper)
+                        (progDesc "Show or set config" <> footerDoc (Just $ text configFooter))
+               )
           <> commandGroup "Other commands:"
           <> hidden
           )
@@ -482,6 +495,17 @@ Examples:
   ghcup prefetch ghc 8.10.5
   ghcup --offline install ghc 8.10.5|]
 
+configFooter :: String
+configFooter = [s|Examples:
+
+# show current config
+ghcup config
+
+# initialize config
+ghcup config init
+
+# set <key> <value> configuration pair
+ghcup config <key> <value>|]
 
 installCabalFooter :: String
 installCabalFooter = [s|Discussion:
@@ -574,7 +598,7 @@ Examples:
 
 installOpts :: Maybe Tool -> Parser InstallOptions
 installOpts tool =
-  (\p (u, v) b -> InstallOptions v p u b)
+  (\p (u, v) b is -> InstallOptions v p u b is)
     <$> optional
           (option
             (eitherReader platformParser)
@@ -603,6 +627,15 @@ installOpts tool =
           (long "set" <> help
             "Set as active version after install"
           )
+    <*> optional
+          (option
+           (eitherReader isolateParser)
+           (  short 'i'
+           <> long "isolate"
+           <> metavar "DIR"
+           <> help "install in an isolated dir instead of the default one"
+           )
+          )
 
 
 setParser :: Parser (Either SetCommand SetOptions)
@@ -786,6 +819,19 @@ Examples:
   # build cross compiler
   ghcup compile ghc -j 4 -v 8.4.2 -b 8.2.2 -x armv7-unknown-linux-gnueabihf --config $(pwd)/build.mk -- --enable-unregisterised|]
 
+configP :: Parser ConfigCommand
+configP = subparser
+      (  command "init" initP
+      <> command "set"  setP -- [set] KEY VALUE at help lhs
+      <> command "show" showP
+      )
+    <|> argsP -- add show for a single option
+    <|> pure ShowConfig
+ where
+  initP = info (pure InitConfig) (progDesc "Write default config to ~/.ghcup/config.yaml")
+  showP = info (pure ShowConfig) (progDesc "Show current config (default)")
+  setP  = info argsP (progDesc "Set config KEY to VALUE")
+  argsP = SetConfig <$> argument str (metavar "KEY") <*> argument str (metavar "VALUE")
 
 whereisP :: Parser WhereisCommand
 whereisP = subparser
@@ -1000,6 +1046,15 @@ ghcCompileOpts =
     <*> switch
           (long "hadrian" <> help "Use the hadrian build system instead of make (only git versions seem to be properly supported atm)"
           )
+    <*> optional
+          (option
+            (eitherReader isolateParser)
+            (  short 'i'
+            <> long "isolate"
+            <> metavar "DIR"
+            <> help "install in an isolated directory instead of the default one, no symlinks to this installation will be made"
+            )
+           )
 
 
 toolVersionParser :: Parser ToolVersion
@@ -1215,6 +1270,10 @@ platformParser s' = case MP.parse (platformP <* MP.eof) "" (T.pack s') of
 bindistParser :: String -> Either String URI
 bindistParser = first show . parseURI strictURIParserOptions . UTF8.fromString
 
+isolateParser :: FilePath -> Either String FilePath
+isolateParser f = case isValid f of
+              True -> Right $ normalise f
+              False -> Left "Please enter a valid filepath for isolate dir."
 
 toSettings :: Options -> IO (Settings, KeyBindings)
 toSettings options = do
@@ -1258,6 +1317,21 @@ toSettings options = do
          , bShowAllTools = fromMaybe bShowAllTools kShowAllTools
          }
 
+updateSettings :: Monad m => UTF8.ByteString -> Settings -> Excepts '[JSONError] m Settings
+updateSettings config settings = do
+  settings' <- lE' JSONDecodeError . first show . Y.decodeEither' $ config
+  pure $ mergeConf settings' settings
+  where
+   mergeConf :: UserSettings -> Settings -> Settings
+   mergeConf UserSettings{..} Settings{..} =
+     let cache'      = fromMaybe cache uCache
+         noVerify'   = fromMaybe noVerify uNoVerify
+         keepDirs'   = fromMaybe keepDirs uKeepDirs
+         downloader' = fromMaybe downloader uDownloader
+         verbose'    = fromMaybe verbose uVerbose
+         urlSource'  = fromMaybe urlSource uUrlSource
+         noNetwork'  = fromMaybe noNetwork uNoNetwork
+     in Settings cache' noVerify' keepDirs' downloader' verbose' urlSource' noNetwork'
 
 upgradeOptsP :: Parser UpgradeOpts
 upgradeOptsP =
@@ -1292,6 +1366,11 @@ describe_result = $( LitE . StringL <$>
                      )
                    )
 
+formatConfig :: UserSettings -> String
+formatConfig settings
+  = UTF8.toString . YP.encodePretty yamlConfig $ settings
+ where
+  yamlConfig = YP.setConfCompare compare YP.defConfig
 
 main :: IO ()
 main = do
@@ -1445,6 +1524,8 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
 #endif
                       , FileDoesNotExistError
                       , CopyError
+                      , NotInstalled
+                      , DirNotEmpty
                       , NoDownload
                       , NotInstalled
                       , BuildFailed
@@ -1454,6 +1535,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                       , TarDirDoesNotExist
                       , NextVerNotFound
                       , NoToolVersionSet
+                      , FileAlreadyExistsError
                       ]
 
           let runInstTool mInstPlatform action' = do
@@ -1555,6 +1637,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                       , UnknownArchive
                       , TarDirDoesNotExist
                       , NotInstalled
+                      , DirNotEmpty
 #if !defined(TAR)
                       , ArchiveResult
 #endif
@@ -1617,22 +1700,23 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
           -----------------------
 
           let installGHC InstallOptions{..} =
-                  (case instBindist of
-                     Nothing -> runInstTool instPlatform $ do
+                (case instBindist of
+                   Nothing -> runInstTool instPlatform $ do
+                     (v, vi) <- liftE $ fromVersion instVer GHC
+                     liftE $ installGHCBin (_tvVersion v) isolateDir
+                     when instSet $ void $ liftE $ setGHC v SetGHCOnly
+                     pure vi
+                   Just uri -> do
+                     s' <- liftIO appState
+                     runInstTool' s'{ settings = settings {noVerify = True}} instPlatform $ do
                        (v, vi) <- liftE $ fromVersion instVer GHC
-                       liftE $ installGHCBin (_tvVersion v)
+                       liftE $ installGHCBindist
+                         (DownloadInfo uri (Just $ RegexDir "ghc-.*") "")
+                         (_tvVersion v)
+                         isolateDir
                        when instSet $ void $ liftE $ setGHC v SetGHCOnly
                        pure vi
-                     Just uri -> do
-                       s' <- liftIO appState
-                       runInstTool' s'{ settings = settings {noVerify = True}} instPlatform $ do
-                         (v, vi) <- liftE $ fromVersion instVer GHC
-                         liftE $ installGHCBindist
-                           (DownloadInfo uri (Just $ RegexDir "ghc-.*") "")
-                           (_tvVersion v)
-                         when instSet $ void $ liftE $ setGHC v SetGHCOnly
-                         pure vi
-                    )
+                  )
                     >>= \case
                           VRight vi -> do
                             runLogger $ $(logInfo) "GHC installation successful"
@@ -1661,7 +1745,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                 (case instBindist of
                    Nothing -> runInstTool instPlatform $ do
                      (v, vi) <- liftE $ fromVersion instVer Cabal
-                     liftE $ installCabalBin (_tvVersion v)
+                     liftE $ installCabalBin (_tvVersion v) isolateDir
                      pure vi
                    Just uri -> do
                      s' <- appState
@@ -1670,6 +1754,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                        liftE $ installCabalBindist
                            (DownloadInfo uri Nothing "")
                            (_tvVersion v)
+                           isolateDir
                        pure vi
                   )
                   >>= \case
@@ -1689,10 +1774,10 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                           pure $ ExitFailure 4
 
           let installHLS InstallOptions{..} =
-                (case instBindist of
+                 (case instBindist of
                    Nothing -> runInstTool instPlatform $ do
                      (v, vi) <- liftE $ fromVersion instVer HLS
-                     liftE $ installHLSBin (_tvVersion v)
+                     liftE $ installHLSBin (_tvVersion v) isolateDir
                      pure vi
                    Just uri -> do
                      s' <- appState
@@ -1701,6 +1786,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                        liftE $ installHLSBindist
                            (DownloadInfo uri Nothing "")
                            (_tvVersion v)
+                           isolateDir
                        pure vi
                   )
                   >>= \case
@@ -1720,19 +1806,20 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                           pure $ ExitFailure 4
 
           let installStack InstallOptions{..} =
-                (case instBindist of
-                   Nothing -> runInstTool instPlatform $ do
-                     (v, vi) <- liftE $ fromVersion instVer Stack
-                     liftE $ installStackBin (_tvVersion v)
-                     pure vi
-                   Just uri -> do
-                     s' <- appState
-                     runInstTool' s'{ settings = settings { noVerify = True}} instPlatform $ do
-                       (v, vi) <- liftE $ fromVersion instVer Stack
-                       liftE $ installStackBindist
-                           (DownloadInfo uri Nothing "")
-                           (_tvVersion v)
-                       pure vi
+                 (case instBindist of
+                    Nothing -> runInstTool instPlatform $ do
+                      (v, vi) <- liftE $ fromVersion instVer Stack
+                      liftE $ installStackBin (_tvVersion v) isolateDir
+                      pure vi
+                    Just uri -> do
+                      s' <- appState
+                      runInstTool' s'{ settings = settings { noVerify = True}} instPlatform $ do
+                        (v, vi) <- liftE $ fromVersion instVer Stack
+                        liftE $ installStackBindist
+                            (DownloadInfo uri Nothing "")
+                            (_tvVersion v)
+                            isolateDir
+                        pure vi
                   )
                   >>= \case
                         VRight vi -> do
@@ -1961,6 +2048,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                             addConfArgs
                             buildFlavour
                             hadrian
+                            isolateDir
                 GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
                 let vi = getVersionInfo (_tvVersion targetVer) GHC dls
                 when setCompile $ void $ liftE $
@@ -1990,6 +2078,37 @@ Make sure to clean up #{tmpdir} afterwards.|])
                         runLogger $ $(logError) $ T.pack $ prettyShow e
                         pure $ ExitFailure 9
 
+            Config InitConfig -> do
+              path <- getConfigFilePath
+              writeFile path $ formatConfig $ fromSettings settings (Just keybindings)
+              runLogger $ $(logDebug) [i|"config.yaml initialized at #{path}|]
+              pure ExitSuccess
+
+            Config ShowConfig -> do
+              putStrLn $ formatConfig $ fromSettings settings (Just keybindings)
+              pure ExitSuccess
+
+            Config (SetConfig k v) -> do
+              case v of
+                "" -> do
+                  runLogger $ $(logError) "Empty values are not allowed"
+                  pure $ ExitFailure 55
+                _  -> do
+                  r <- runE @'[JSONError] $ do
+                    settings' <- updateSettings [i|#{k}: #{v}\n|] settings
+                    path <- liftIO getConfigFilePath
+                    liftIO $ writeFile path $ formatConfig $ fromSettings settings' (Just keybindings)
+                    runLogger $ $(logDebug) $ T.pack $ show settings'
+                    pure ()
+
+                  case r of
+                      VRight _ -> pure ExitSuccess
+                      VLeft (V (JSONDecodeError e)) -> do
+                        runLogger $ $(logError)
+                          [i|Error decoding config: #{e}|]
+                        pure $ ExitFailure 65
+                      VLeft _ -> pure $ ExitFailure 65
+
             Whereis WhereisOptions{..} (WhereisTool tool (Just (ToolVersion v))) ->
               runLeanWhereIs (do
                 loc <- liftE $ whereIsTool tool v

bootstrap-haskell

@@ -8,7 +8,6 @@
 #   * BOOTSTRAP_HASKELL_GHC_VERSION - the ghc version to install
 #   * BOOTSTRAP_HASKELL_CABAL_VERSION - the cabal version to install
 #   * BOOTSTRAP_HASKELL_INSTALL_STACK - whether to install latest stack
-#   * BOOTSTRAP_HASKELL_INSTALL_STACK_HOOK - whether to install stack hook as well
 #   * BOOTSTRAP_HASKELL_INSTALL_HLS - whether to install latest hls
 #   * BOOTSTRAP_HASKELL_ADJUST_BASHRC - whether to adjust PATH in bashrc (prepend)
 #   * BOOTSTRAP_HASKELL_ADJUST_CABAL_CONFIG - whether to adjust mingw paths in cabal.config on windows
@@ -509,25 +508,17 @@ ask_hls() {
 
 ask_stack() {
 	if [ -n "${BOOTSTRAP_HASKELL_INSTALL_STACK}" ] ; then
-		if [ -n "${BOOTSTRAP_HASKELL_INSTALL_STACK_HOOK}" ] ; then
-			return 2
-		else
-			return 1
-		fi
+		return 1
 	fi
 
 	if [ -z "${BOOTSTRAP_HASKELL_NONINTERACTIVE}" ] ; then
 		echo "-------------------------------------------------------------------------------"
 
-		warn "Do you want to install stack and stack hooks?"
-		warn ""
+		warn "Do you want to install stack?"
 		warn "Stack is a haskell build tool similar to cabal that is used by some projects."
 		warn "Also see https://docs.haskellstack.org/"
 		warn ""
-		warn "Stack hooks allow stack to use ghcup for GHC installation (usually stack handles"
-		warn "installation itself, leading to possibly duplicated GHC versions)."
-		warn ""
-		warn "[Y] Yes, with hooks  [L] Yes, no hooks  [N] No  [?] Help (default is \"N\")."
+		warn "[Y] Yes  [N] No  [?] Help (default is \"N\")."
 		warn ""
 
 		while true; do
@@ -535,16 +526,13 @@ ask_stack() {
 
 			case $stack_answer in
 				[Yy]*)
-					return 2 ;;
-				[Ll]*)
 					return 1 ;;
 				[Nn]* | "")
 					return 0 ;;
 				*)
 					echo "Possible choices are:"
 					echo
-					echo "Y - Yes, install stack with hooks"
-					echo "L - Yes, install stack without hooks"
+					echo "Y - Yes, install stack"
 					echo "N - No, don't install anything more (default)"
 					echo
 					echo "Please make your choice and press ENTER."
@@ -648,27 +636,7 @@ esac
 
 case $ask_stack_answer in
 	1)
-		{
-			_eghcup --cache install stack
-			edo stack update
-		} || warn "Stack installation failed, continuing anyway"
-		;;
-	2)
-		{
-			_eghcup --cache install stack
-		    edo stack update
-			if [ -n "${STACK_ROOT}" ] ; then
-				stack_root=$STACK_ROOT
-			else
-				stack_root=${HOME}/.stack
-			fi
-			edo mkdir -p "${stack_root}/hooks/"
-			edo curl -Lf "https://www.haskell.org/ghcup/sh/hooks/stack/ghc-install.sh" > "${stack_root}/hooks/ghc-install.sh"
-			edo chmod +x "${stack_root}/hooks/ghc-install.sh"
-			edo stack config set system-ghc  false --global
-			edo stack config set install-ghc false --global
-
-		} || warn "Stack installation failed, continuing anyway"
+		_eghcup --cache install stack || warn "Stack installation failed, continuing anyway"
 		;;
 	*) ;;
 esac

bootstrap-haskell.ps1

@@ -29,8 +29,6 @@ param (
     [switch]$InBash,
     # Whether to install stack as well
     [switch]$InstallStack,
-    # Whether to install stack hooks as well
-    [switch]$InstallStackHook,
     # Whether to install hls as well
     [switch]$InstallHLS,
     # Skip adjusting cabal.config with mingw paths
@@ -225,7 +223,6 @@ $null = [Environment]::SetEnvironmentVariable("GHCUP_INSTALL_BASE_PREFIX", $Ghcu
 
 
 $GhcupDir = ('{0}\ghcup' -f $GhcupBasePrefix)
-$StackDir = ('{0}\sr' -f $GhcupBasePrefix)
 $MsysDir = ('{0}\msys64' -f $GhcupDir)
 $Bash = ('{0}\usr\bin\bash' -f $MsysDir)
 if (!($BootstrapUrl)) {
@@ -313,28 +310,15 @@ if (!($InstallHLS)) {
 }
 
 # ask whether to install stack
-$InstallStackDoc = @'
-Do you want to install stack and stack hooks?
-
-Stack is a haskell build tool similar to cabal that is used by some projects.
-Also see https://docs.haskellstack.org/
-
-Stack hooks allow stack to use ghcup for GHC installation (usually stack handles
-installation itself, leading to possibly duplicated GHC versions).
-'@
 if (!($InstallStack)) {
   if (!($Silent)) {
     $StackDecision = $Host.UI.PromptForChoice('Install stack'
-      , $InstallStackDoc
-      , [System.Management.Automation.Host.ChoiceDescription[]] @('&Yes, with hooks'
-          '&Light install, without hooks'
+      , 'Do you want to install stack as well?'
+      , [System.Management.Automation.Host.ChoiceDescription[]] @('&Yes'
           '&No'
-          '&Abort'), 2)
+          '&Abort'), 1)
 
     if ($StackDecision -eq 0) {
-      $InstallStack = $true
-	  $InstallStackHook = $true
-    } elseif ($StackDecision -eq 1) {
       $InstallStack = $true
     } elseif ($StackDecision -eq 2) {
       Exit 0
@@ -387,7 +371,7 @@ if (!(Test-Path -Path ('{0}' -f $MsysDir))) {
     Exec "$Bash" '-lc' 'pacman --noconfirm -Syuu'
 
     Print-Msg -msg 'Installing Dependencies...'
-    Exec "$Bash" '-lc' 'pacman --noconfirm -S --needed curl mingw-w64-x86_64-pkgconf'
+    Exec "$Bash" '-lc' 'pacman --noconfirm -S --needed curl autoconf mingw-w64-x86_64-pkgconf'
 
     Print-Msg -msg 'Updating SSL root certificate authorities...'
     Exec "$Bash" '-lc' 'pacman --noconfirm -S ca-certificates'
@@ -515,11 +499,6 @@ $SilentExport = 'export BOOTSTRAP_HASKELL_NONINTERACTIVE=1 ;'
 
 if ($InstallStack) {
   $StackInstallExport = 'export BOOTSTRAP_HASKELL_INSTALL_STACK=1 ;'
-  $null = [Environment]::SetEnvironmentVariable("STACK_ROOT", $StackDir, [System.EnvironmentVariableTarget]::User)
-}
-
-if ($InstallStackHook) {
-  $StackInstallHookExport = 'export BOOTSTRAP_HASKELL_INSTALL_STACK_HOOK=1 ;'
 }
 
 if ($InstallHLS) {
@@ -531,9 +510,9 @@ if (!($NoAdjustCabalConfig)) {
 }
 
 if ((Get-Process -ID $PID).ProcessName.StartsWith("bootstrap-haskell") -Or $InBash) {
-  Exec "$Bash" '-lc' ('{4} {6} {7} {8} {9} [ -n ''{1}'' ] && export GHCUP_MSYS2=$(cygpath -m ''{1}'') ; [ -n ''{2}'' ] && export GHCUP_INSTALL_BASE_PREFIX=$(cygpath -m ''{2}/'') ; export PATH=$(cygpath -u ''{3}/bin''):$PATH ; export CABAL_DIR=''{5}'' ; export STACK_ROOT=$(cygpath -m ''{10}/'') ; [[ ''{0}'' = https* ]]  && curl --proto ''=https'' --tlsv1.2 -sSf {0} | bash || cat $(cygpath -m ''{0}'') | bash' -f $BootstrapUrl, $MsysDir, $GhcupBasePrefix, $GhcupDir, $SilentExport, $CabalDirFull, $StackInstallExport, $HLSInstallExport, $AdjustCabalConfigExport, $StackInstallHookExport, $StackDir)
+  Exec "$Bash" '-lc' ('{4} {6} {7} {8} [ -n ''{1}'' ] && export GHCUP_MSYS2=$(cygpath -m ''{1}'') ; [ -n ''{2}'' ] && export GHCUP_INSTALL_BASE_PREFIX=$(cygpath -m ''{2}/'') ; export PATH=$(cygpath -u ''{3}/bin''):$PATH ; export CABAL_DIR=''{5}'' ; [[ ''{0}'' = https* ]]  && curl --proto ''=https'' --tlsv1.2 -sSf {0} | bash || cat $(cygpath -m ''{0}'') | bash' -f $BootstrapUrl, $MsysDir, $GhcupBasePrefix, $GhcupDir, $SilentExport, $CabalDirFull, $StackInstallExport, $HLSInstallExport, $AdjustCabalConfigExport)
 } else {
-  Exec "$Msys2Shell" '-mingw64' '-mintty' '-c' ('{4} {6} {7} {8} {9} [ -n ''{1}'' ] && export GHCUP_MSYS2=$(cygpath -m ''{1}'') ; [ -n ''{2}'' ] && export GHCUP_INSTALL_BASE_PREFIX=$(cygpath -m ''{2}/'') ; export PATH=$(cygpath -u ''{3}/bin''):$PATH ; export CABAL_DIR=''{5}'' ; export STACK_ROOT=$(cygpath -m ''{10}/'') ; trap ''echo Press any key to exit && read -n 1 && exit'' 2 ; [[ ''{0}'' = https* ]]  && curl --proto ''=https'' --tlsv1.2 -sSf {0} | bash || cat $(cygpath -m ''{0}'') | bash ; echo ''Press any key to exit'' && read -n 1' -f $BootstrapUrl, $MsysDir, $GhcupBasePrefix, $GhcupDir, $SilentExport, $CabalDirFull, $StackInstallExport, $HLSInstallExport, $AdjustCabalConfigExport, $StackInstallHookExport, $StackDir)
+  Exec "$Msys2Shell" '-mingw64' '-mintty' '-c' ('{4} {6} {7} {8} [ -n ''{1}'' ] && export GHCUP_MSYS2=$(cygpath -m ''{1}'') ; [ -n ''{2}'' ] && export GHCUP_INSTALL_BASE_PREFIX=$(cygpath -m ''{2}/'') ; export PATH=$(cygpath -u ''{3}/bin''):$PATH ; export CABAL_DIR=''{5}'' ; trap ''echo Press any key to exit && read -n 1 && exit'' 2 ; [[ ''{0}'' = https* ]]  && curl --proto ''=https'' --tlsv1.2 -sSf {0} | bash || cat $(cygpath -m ''{0}'') | bash ; echo ''Press any key to exit'' && read -n 1' -f $BootstrapUrl, $MsysDir, $GhcupBasePrefix, $GhcupDir, $SilentExport, $CabalDirFull, $StackInstallExport, $HLSInstallExport, $AdjustCabalConfigExport)
 }
 
 

ghcup-0.0.6.yaml

@@ -2206,7 +2206,8 @@ ghcupDownloads:
             unknown_versioning: *stack-271-64
     2.7.3:
       viTags:
-        - old
+        - Latest
+        - Recommended
       viChangeLog: https://github.com/commercialhaskell/stack/blob/master/ChangeLog.md#v273
       viPostInstall: *stack-post
       viArch:
@@ -2231,65 +2232,4 @@ ghcupDownloads:
                 RegexDir: "stack-.*"
           Linux_Alpine:
             unknown_versioning: *stack-273-64
-    2.7.3.1:
-      viTags:
-        - Latest
-        - Recommended
-      viChangeLog: https://github.com/commercialhaskell/stack/blob/master/ChangeLog.md#v273
-      viPostInstall: &stack-post-new |
-        Stack manages GHC versions internally by default. It can also use hooks to automatically
-        install and locate GHC versions utilizing GHCup:
-          https://gitlab.haskell.org/haskell/ghcup-hs#stack-hooks
 
-        Alternatively, you can also tell stack to use the system GHC version (whatever is in PATH):
-          stack config set system-ghc  true  --global
-
-        If you want stack to use GHCup's provided MSys2, follow the instructions here (not recommended):
-          https://gitlab.haskell.org/haskell/ghcup-hs/-/tree/stack-fork#sharing-msys2-between-stack-and-ghcup
-
-        Also check out: https://docs.haskellstack.org/en/stable/yaml_configuration
-
-        !!! GHCup ships a patched version of stack. Before reporting bugs to stack developers !!!
-        !!! make sure it is reproducible with the original stack version:                     !!!
-        !!!   https://docs.haskellstack.org/en/stable/install_and_upgrade/                    !!!
-      viArch:
-        A_64:
-          Linux_UnknownLinux:
-            unknown_versioning: &stack-2731-64
-              dlUri: https://downloads.haskell.org/ghcup/unofficial-bindists/stack/2.7.3.1/stack-2.7.3.1-linux-x86_64.tar.gz
-              dlSubdir:
-                RegexDir: "stack-.*"
-              dlHash: 7c10090d568651208b6d6c003c8d78ef79099f4b472aea5ca800f3e4a7a1c6ce
-          Darwin:
-            unknown_versioning:
-              dlUri: https://downloads.haskell.org/ghcup/unofficial-bindists/stack/2.7.3.1/stack-2.7.3.1-osx-x86_64.tar.gz
-              dlSubdir:
-                RegexDir: "stack-.*"
-              dlHash: 23030868be377d62ed324332d239ddd915b12f7a64c887f297e1b60a3f65894f
-          Windows:
-            unknown_versioning:
-              dlUri: https://downloads.haskell.org/ghcup/unofficial-bindists/stack/2.7.3.1/stack-2.7.3.1-windows-x86_64.tar.bz2
-              dlHash: 983ac24219370cdf220f47f9edb17d0aeb831a1253fd777d322fd1bff358c511
-          Linux_Alpine:
-            unknown_versioning: *stack-2731-64
-          FreeBSD:
-            unknown_versioning:
-              dlUri: https://downloads.haskell.org/ghcup/unofficial-bindists/stack/2.7.3.1/stack-2.7.3.1-freebsd-x86_64.tar.gz
-              dlHash: b6b1eb59981b8c1d3a04b061f03296b1540ecbadbc34cbd4fe712a575a155ee9
-        A_32:
-          Linux_UnknownLinux:
-            unknown_versioning: &stack-2731-32
-              dlUri: https://downloads.haskell.org/ghcup/unofficial-bindists/stack/2.7.3.1/stack-2.7.3.1-linux-i386.tar.gz
-              dlHash: da2081d84517d16a8216e929582dd39caa19643c819b77c6f68f138bd177a758
-          Linux_Alpine:
-            unknown_versioning: *stack-2731-32
-        A_ARM64:
-          Linux_UnknownLinux:
-            unknown_versioning:
-              dlUri: https://downloads.haskell.org/ghcup/unofficial-bindists/stack/2.7.3.1/stack-2.7.3.1-linux-aarch64.tar.gz
-              dlHash: 0e1789852a476dd87f495fa0b481309398b2bafc00cf7c8d980c91977b39d9a6
-        A_ARM:
-          Linux_UnknownLinux:
-            unknown_versioning:
-              dlUri: https://downloads.haskell.org/ghcup/unofficial-bindists/stack/2.7.3.1/stack-2.7.3.1-linux-armv7.tar.gz
-              dlHash: 13d61616c169615d80381ea0c84e13540410b736a553565cd48d10b4d2bd7f23

ghcup.cabal

@@ -1,6 +1,6 @@
 cabal-version:   3.0
 name:            ghcup
-version:         0.1.16.1
+version:         0.1.16.2
 license:         LGPL-3.0-only
 license-file:    LICENSE
 copyright:       Julian Ospald 2020
@@ -226,6 +226,7 @@ executable ghcup
     , uri-bytestring        ^>=0.3.2.2
     , utf8-string           ^>=1.0
     , versions              >=4.0.1    && <5.1
+    , yaml                  ^>=0.11.4.0
 
   if flag(internal-downloader)
     cpp-options: -DINTERNAL_DOWNLOADER

hooks/stack/ghc-install.sh

@@ -1,23 +0,0 @@
-#!/bin/sh
-
-set -eu
-
-case $HOOK_GHC_TYPE in
-	bindist)
-		ghcup --offline whereis ghc $HOOK_GHC_VERSION || {
-			ghcup --cache install ghc $HOOK_GHC_VERSION && ghcup whereis ghc $HOOK_GHC_VERSION
-		}
-		;;
-	git)
-		>&2 echo "Hook doesn't support installing from source."
-		>&2 echo "Consider enabling stack GHC installs for this project, via:"
-		>&2 echo "    stack config set install-ghc true"
-		exit 1
-		;;
-	*)
-		>&2 echo "Unsupported GHC installation type: ${HOOK_GHC_TYPE}."
-		>&2 echo "Consider enabling stack GHC installs for this project, via:"
-		>&2 echo "    stack config set install-ghc true"
-		exit 2
-		;;
-esac

lib/GHCup.hs

@@ -186,6 +186,7 @@ installGHCBindist :: ( MonadFail m
                      )
                   => DownloadInfo    -- ^ where/how to download
                   -> Version         -- ^ the version to install
+                  -> Maybe FilePath  -- ^ isolated filepath if user passed any
                   -> Excepts
                        '[ AlreadyInstalled
                         , BuildFailed
@@ -195,16 +196,22 @@ installGHCBindist :: ( MonadFail m
                         , NotInstalled
                         , UnknownArchive
                         , TarDirDoesNotExist
+                        , DirNotEmpty
 #if !defined(TAR)
                         , ArchiveResult
 #endif
                         ]
                        m
                        ()
-installGHCBindist dlinfo ver = do
+installGHCBindist dlinfo ver isoFilepath = do
   let tver = mkTVer ver
+
   lift $ $(logDebug) [i|Requested to install GHC with #{ver}|]
-  whenM (lift $ ghcInstalled tver) (throwE $ AlreadyInstalled GHC ver)
+
+  case isoFilepath of
+    -- we only care for already installed errors in regular (non-isolated) installs
+    Nothing -> whenM (lift $ ghcInstalled tver) (throwE $ AlreadyInstalled GHC ver)
+    _ -> pure ()
 
   -- download (or use cached version)
   dl <- liftE $ downloadCached dlinfo Nothing
@@ -214,9 +221,15 @@ installGHCBindist dlinfo ver = do
 
   toolchainSanityChecks
   
-  liftE $ installPackedGHC dl (view dlSubdir dlinfo) ghcdir ver
+  case isoFilepath of
+    Just isoDir -> do                        -- isolated install
+      lift $ $(logInfo) [i|isolated installing GHC to #{isoDir}|]
+      liftE $ installPackedGHC dl (view dlSubdir dlinfo) isoDir ver
+    Nothing -> do                            -- regular install
+      liftE $ installPackedGHC dl (view dlSubdir dlinfo) ghcdir ver
 
-  liftE $ postGHCInstall tver
+      -- make symlinks & stuff when regular install,
+      liftE $ postGHCInstall tver
 
  where
   toolchainSanityChecks = do
@@ -250,6 +263,7 @@ installPackedGHC :: ( MonadMask m
                       '[ BuildFailed
                        , UnknownArchive
                        , TarDirDoesNotExist
+                       , DirNotEmpty
 #if !defined(TAR)
                        , ArchiveResult
 #endif
@@ -257,6 +271,8 @@ installPackedGHC :: ( MonadMask m
 installPackedGHC dl msubdir inst ver = do
   PlatformRequest {..} <- lift getPlatformReq
 
+  liftE $ installDestSanityCheck inst
+
   -- unpack
   tmpUnpack <- lift mkGhcupTmpDir
   liftE $ unpackToDir tmpUnpack dl
@@ -270,6 +286,22 @@ installPackedGHC dl msubdir inst ver = do
   liftE $ runBuildAction tmpUnpack
                          (Just inst)
                          (installUnpackedGHC workdir inst ver)
+ where
+  -- | Does basic checks for isolated installs
+  -- Isolated Directory:
+  --   1. if it doesn't exist -> proceed
+  --   2. if it exists and is empty -> proceed
+  --   3. if it exists and is non-empty -> panic and leave the house
+  installDestSanityCheck :: ( MonadIO m
+                            , MonadCatch m
+                            ) =>
+                            FilePath ->
+                            Excepts '[DirNotEmpty] m ()
+  installDestSanityCheck isoDir = do
+    hideErrorDef [doesNotExistErrorType] () $ do
+      contents <- liftIO $ getDirectoryContentsRecursive isoDir
+      unless (null contents) (throwE $ DirNotEmpty isoDir)
+
 
 
 -- | Install an unpacked GHC distribution. This only deals with the GHC
@@ -300,10 +332,6 @@ installUnpackedGHC path inst ver = do
     setModificationTime dest mtime
 #else
   PlatformRequest {..} <- lift getPlatformReq
-  liftIO $ copyDirectoryRecursive path inst $ \source dest -> do
-    mtime <- getModificationTime source
-    copyFile source dest
-    setModificationTime dest mtime
 
   let alpineArgs
        | ver >= [vver|8.2.2|], Linux Alpine <- _rPlatform
@@ -343,6 +371,7 @@ installGHCBin :: ( MonadFail m
                  , MonadUnliftIO m
                  )
               => Version         -- ^ the version to install
+              -> Maybe FilePath  -- ^ isolated install filepath, if user passed any
               -> Excepts
                    '[ AlreadyInstalled
                     , BuildFailed
@@ -352,15 +381,16 @@ installGHCBin :: ( MonadFail m
                     , NotInstalled
                     , UnknownArchive
                     , TarDirDoesNotExist
+                    , DirNotEmpty
 #if !defined(TAR)
                     , ArchiveResult
 #endif
                     ]
                    m
                    ()
-installGHCBin ver = do
+installGHCBin ver isoFilepath = do
   dlinfo <- liftE $ getDownloadInfo GHC ver
-  installGHCBindist dlinfo ver
+  installGHCBindist dlinfo ver isoFilepath
 
 
 -- | Like 'installCabalBin', except takes the 'DownloadInfo' as
@@ -379,6 +409,7 @@ installCabalBindist :: ( MonadMask m
                        )
                     => DownloadInfo
                     -> Version
+                    -> Maybe FilePath -- ^ isolated install filepath, if user provides any.
                     -> Excepts
                          '[ AlreadyInstalled
                           , CopyError
@@ -391,23 +422,28 @@ installCabalBindist :: ( MonadMask m
 #if !defined(TAR)
                           , ArchiveResult
 #endif
+                          , FileAlreadyExistsError
                           ]
                          m
                          ()
-installCabalBindist dlinfo ver = do
+installCabalBindist dlinfo ver isoFilepath = do
   lift $ $(logDebug) [i|Requested to install cabal version #{ver}|]
 
   PlatformRequest {..} <- lift getPlatformReq
   Dirs {..} <- lift getDirs
 
-  whenM
-      (lift (cabalInstalled ver) >>= \a -> liftIO $
-        handleIO (\_ -> pure False)
-          $ fmap (\x -> a && x)
-          -- ignore when the installation is a legacy cabal (binary, not symlink)
-          $ pathIsLink (binDir </> "cabal" <> exeExt)
-      )
-      (throwE $ AlreadyInstalled Cabal ver)
+  case isoFilepath of
+    Nothing -> -- for regular install check if any previous versions installed
+      whenM
+        (lift (cabalInstalled ver) >>= \a -> liftIO $
+          handleIO (\_ -> pure False)
+            $ fmap (\x -> a && x)
+            -- ignore when the installation is a legacy cabal (binary, not symlink)
+            $ pathIsLink (binDir </> "cabal" <> exeExt)
+        )
+        (throwE $ AlreadyInstalled Cabal ver)
+
+    _ -> pure () -- check isn't required in isolated installs
 
   -- download (or use cached version)
   dl <- liftE $ downloadCached dlinfo Nothing
@@ -420,30 +456,37 @@ installCabalBindist dlinfo ver = do
   -- the subdir of the archive where we do the work
   workdir <- maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
 
-  liftE $ installCabal' workdir binDir
+  case isoFilepath of
+    Just isoDir -> do             -- isolated install
+      lift $ $(logInfo) [i|isolated installing Cabal to #{isoDir}|]
+      liftE $ installCabalUnpacked workdir isoDir Nothing
 
-  -- create symlink if this is the latest version
-  cVers <- lift $ fmap rights getInstalledCabals
-  let lInstCabal = headMay . reverse . sort $ cVers
-  when (maybe True (ver >=) lInstCabal) $ liftE $ setCabal ver
+    Nothing -> do                 -- regular install
+      liftE $ installCabalUnpacked workdir binDir (Just ver)
 
- where
-  -- | Install an unpacked cabal distribution.
-  installCabal' :: (MonadLogger m, MonadCatch m, MonadIO m)
-                => FilePath      -- ^ Path to the unpacked cabal bindist (where the executable resides)
-                -> FilePath      -- ^ Path to install to
-                -> Excepts '[CopyError] m ()
-  installCabal' path inst = do
-    lift $ $(logInfo) "Installing cabal"
-    let cabalFile = "cabal"
-    liftIO $ createDirRecursive' inst
-    let destFileName = cabalFile <> "-" <> T.unpack (prettyVer ver) <> exeExt
-    let destPath = inst </> destFileName
-    handleIO (throwE . CopyError . show) $ liftIO $ copyFile
-      (path </> cabalFile <> exeExt)
-      destPath
-    lift $ chmod_755 destPath
+      -- create symlink if this is the latest version for regular installs
+      cVers <- lift $ fmap rights getInstalledCabals
+      let lInstCabal = headMay . reverse . sort $ cVers
+      when (maybe True (ver >=) lInstCabal) $ liftE $ setCabal ver
 
+-- | Install an unpacked cabal distribution.
+installCabalUnpacked :: (MonadLogger m, MonadCatch m, MonadIO m)
+              => FilePath      -- ^ Path to the unpacked cabal bindist (where the executable resides)
+              -> FilePath      -- ^ Path to install to
+              -> Maybe Version -- ^ Nothing for isolated install
+              -> Excepts '[CopyError, FileAlreadyExistsError] m ()
+installCabalUnpacked path inst mver' = do
+  lift $ $(logInfo) "Installing cabal"
+  let cabalFile = "cabal"
+  liftIO $ createDirRecursive' inst
+  let destFileName = cabalFile
+        <> maybe "" (("-" <>) . T.unpack . prettyVer) mver'
+        <> exeExt
+  let destPath = inst </> destFileName
+  handleIO (throwE . CopyError . show) $ liftIO $ copyFile
+    (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
@@ -462,6 +505,7 @@ installCabalBin :: ( MonadMask m
                    , MonadFail m
                    )
                 => Version
+                -> Maybe FilePath -- isolated install Path, if user provided any
                 -> Excepts
                      '[ AlreadyInstalled
                       , CopyError
@@ -474,12 +518,13 @@ installCabalBin :: ( MonadMask m
 #if !defined(TAR)
                       , ArchiveResult
 #endif
+                      , FileAlreadyExistsError
                       ]
                      m
                      ()
-installCabalBin ver = do
+installCabalBin ver isoFilepath = do
   dlinfo <- liftE $ getDownloadInfo Cabal ver
-  installCabalBindist dlinfo ver
+  installCabalBindist dlinfo ver isoFilepath
 
 
 -- | Like 'installHLSBin, except takes the 'DownloadInfo' as
@@ -498,6 +543,7 @@ installHLSBindist :: ( MonadMask m
                      )
                   => DownloadInfo
                   -> Version
+                  -> Maybe FilePath -- ^ isolated install path, if user passed any
                   -> Excepts
                        '[ AlreadyInstalled
                         , CopyError
@@ -513,14 +559,19 @@ installHLSBindist :: ( MonadMask m
                         ]
                        m
                        ()
-installHLSBindist dlinfo ver = do
+installHLSBindist dlinfo ver isoFilepath = do
   lift $ $(logDebug) [i|Requested to install hls version #{ver}|]
 
   PlatformRequest {..} <- lift getPlatformReq
   Dirs {..} <- lift getDirs
 
-  whenM (lift (hlsInstalled ver))
-    (throwE $ AlreadyInstalled HLS ver)
+  case isoFilepath of
+    Nothing ->
+      -- we only check for already installed in regular (non-isolated) installs
+      whenM (lift (hlsInstalled ver))
+      (throwE $ AlreadyInstalled HLS ver)
+
+    _ -> pure ()
 
   -- download (or use cached version)
   dl <- liftE $ downloadCached dlinfo Nothing
@@ -533,46 +584,55 @@ installHLSBindist dlinfo ver = do
   -- the subdir of the archive where we do the work
   workdir <- maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
 
-  liftE $ installHLS' workdir binDir
+  case isoFilepath of
+    Just isoDir -> do
+      lift $ $(logInfo) [i|isolated installing HLS to #{isoDir}|]
+      liftE $ installHLSUnpacked workdir isoDir Nothing
 
-  -- create symlink if this is the latest version
-  hlsVers <- lift $ fmap rights getInstalledHLSs
-  let lInstHLS = headMay . reverse . sort $ hlsVers
-  when (maybe True (ver >=) lInstHLS) $ liftE $ setHLS ver
+    Nothing -> do
+      liftE $ installHLSUnpacked workdir binDir (Just ver)
 
- where
-  -- | Install an unpacked hls distribution.
-  installHLS' :: (MonadFail m, MonadLogger m, MonadCatch m, MonadIO m)
-                => FilePath      -- ^ Path to the unpacked hls bindist (where the executable resides)
-                -> FilePath      -- ^ Path to install to
-                -> Excepts '[CopyError] m ()
-  installHLS' path inst = do
-    lift $ $(logInfo) "Installing HLS"
-    liftIO $ createDirRecursive' inst
+      -- create symlink if this is the latest version in a regular install
+      hlsVers <- lift $ fmap rights getInstalledHLSs
+      let lInstHLS = headMay . reverse . sort $ hlsVers
+      when (maybe True (ver >=) lInstHLS) $ liftE $ setHLS ver
 
-    -- 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
-                <> "~" <> T.unpack (prettyVer ver) <> exeExt
-      handleIO (throwE . CopyError . show) $ liftIO $ copyFile
-        (path </> f)
-        (inst </> toF)
-      lift $ chmod_755 (inst </> toF)
 
-    -- install haskell-language-server-wrapper
-    let wrapper = "haskell-language-server-wrapper"
-        toF = wrapper <> "-" <> T.unpack (prettyVer ver) <> exeExt
+-- | Install an unpacked hls distribution.
+installHLSUnpacked :: (MonadFail m, MonadLogger m, MonadCatch m, MonadIO m)
+              => FilePath      -- ^ Path to the unpacked hls bindist (where the executable resides)
+              -> FilePath      -- ^ Path to install to
+              -> Maybe Version -- ^ Nothing for isolated install
+              -> Excepts '[CopyError] m ()
+installHLSUnpacked path inst mver' = do
+  lift $ $(logInfo) "Installing HLS"
+  liftIO $ createDirRecursive' inst
+
+  -- 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
+              <> maybe "" (("~" <>) . T.unpack . prettyVer) mver'
+              <> exeExt
     handleIO (throwE . CopyError . show) $ liftIO $ copyFile
-      (path </> wrapper <> exeExt)
+      (path </> f)
       (inst </> toF)
     lift $ chmod_755 (inst </> toF)
 
+  -- install haskell-language-server-wrapper
+  let wrapper = "haskell-language-server-wrapper"
+      toF = wrapper
+            <> maybe "" (("-" <>) . T.unpack . prettyVer) mver'
+            <> exeExt
+  handleIO (throwE . CopyError . show) $ liftIO $ copyFile
+    (path </> wrapper <> exeExt)
+    (inst </> toF)
+  lift $ chmod_755 (inst </> toF)
 
 -- | Installs hls binaries @haskell-language-server-\<ghcver\>@
 -- into @~\/.ghcup\/bin/@, as well as @haskell-languager-server-wrapper@.
@@ -590,6 +650,7 @@ installHLSBin :: ( MonadMask m
                  , MonadFail m
                  )
               => Version
+              -> Maybe FilePath
               -> Excepts
                    '[ AlreadyInstalled
                     , CopyError
@@ -605,9 +666,9 @@ installHLSBin :: ( MonadMask m
                     ]
                    m
                    ()
-installHLSBin ver = do
+installHLSBin ver isoFilepath = do
   dlinfo <- liftE $ getDownloadInfo HLS ver
-  installHLSBindist dlinfo ver
+  installHLSBindist dlinfo ver isoFilepath
 
 
 -- | Installs stack into @~\/.ghcup\/bin/stack-\<ver\>@ and
@@ -627,6 +688,7 @@ installStackBin :: ( MonadMask m
                    , MonadFail m
                    )
                 => Version
+                -> Maybe FilePath
                 -> Excepts
                      '[ AlreadyInstalled
                       , CopyError
@@ -642,9 +704,9 @@ installStackBin :: ( MonadMask m
                       ]
                      m
                      ()
-installStackBin ver = do
+installStackBin ver isoFilepath = do
   dlinfo <- liftE $ getDownloadInfo Stack ver
-  installStackBindist dlinfo ver
+  installStackBindist dlinfo ver isoFilepath
 
 
 -- | Like 'installStackBin', except takes the 'DownloadInfo' as
@@ -663,6 +725,7 @@ installStackBindist :: ( MonadMask m
                        )
                     => DownloadInfo
                     -> Version
+                    -> Maybe FilePath
                     -> Excepts
                          '[ AlreadyInstalled
                           , CopyError
@@ -678,14 +741,18 @@ installStackBindist :: ( MonadMask m
                           ]
                          m
                          ()
-installStackBindist dlinfo ver = do
+installStackBindist dlinfo ver isoFilepath = do
   lift $ $(logDebug) [i|Requested to install stack version #{ver}|]
 
   PlatformRequest {..} <- lift getPlatformReq
   Dirs {..} <- lift getDirs
 
-  whenM (lift (stackInstalled ver))
-    (throwE $ AlreadyInstalled Stack ver)
+  case isoFilepath of
+    Nothing ->             -- check previous versions in case of regular installs
+      whenM (lift (stackInstalled ver))
+      (throwE $ AlreadyInstalled Stack ver)
+
+    _ -> pure ()           -- don't do shit for isolates
 
   -- download (or use cached version)
   dl <- liftE $ downloadCached dlinfo Nothing
@@ -698,31 +765,37 @@ installStackBindist dlinfo ver = do
   -- the subdir of the archive where we do the work
   workdir <- maybe (pure tmpUnpack) (liftE . intoSubdir tmpUnpack) (view dlSubdir dlinfo)
 
-  liftE $ installStack' workdir binDir
+  case isoFilepath of
+    Just isoDir -> do                 -- isolated install
+      lift $ $(logInfo) [i|isolated installing Stack to #{isoDir}|]
+      liftE $ installStackUnpacked workdir isoDir Nothing
+    Nothing -> do                     -- regular install
+      liftE $ installStackUnpacked workdir binDir (Just ver)
 
-  -- create symlink if this is the latest version
-  sVers <- lift $ fmap rights getInstalledStacks
-  let lInstStack = headMay . reverse . sort $ sVers
-  when (maybe True (ver >=) lInstStack) $ liftE $ setStack ver
-
- where
-  -- | Install an unpacked stack distribution.
-  installStack' :: (MonadLogger m, MonadCatch m, MonadIO m)
-                => FilePath      -- ^ Path to the unpacked stack bindist (where the executable resides)
-                -> FilePath      -- ^ Path to install to
-                -> Excepts '[CopyError] m ()
-  installStack' path inst = do
-    lift $ $(logInfo) "Installing stack"
-    let stackFile = "stack"
-    liftIO $ createDirRecursive' inst
-    let destFileName = stackFile <> "-" <> T.unpack (prettyVer ver) <> exeExt
-    let destPath = inst </> destFileName
-    handleIO (throwE . CopyError . show) $ liftIO $ copyFile
-      (path </> stackFile <> exeExt)
-      destPath
-    lift $ chmod_755 destPath
+      -- create symlink if this is the latest version and a regular install
+      sVers <- lift $ fmap rights getInstalledStacks
+      let lInstStack = headMay . reverse . sort $ sVers
+      when (maybe True (ver >=) lInstStack) $ liftE $ setStack ver
 
 
+-- | Install an unpacked stack distribution.
+installStackUnpacked :: (MonadLogger m, MonadCatch m, MonadIO m)
+              => FilePath      -- ^ Path to the unpacked stack bindist (where the executable resides)
+              -> FilePath      -- ^ Path to install to
+              -> Maybe Version -- ^ Nothing for isolated installs
+              -> Excepts '[CopyError] m ()
+installStackUnpacked path inst mver' = do
+  lift $ $(logInfo) "Installing stack"
+  let stackFile = "stack"
+  liftIO $ createDirRecursive' inst
+  let destFileName = stackFile
+                     <> maybe "" (("-" <>) .  T.unpack . prettyVer) mver'
+                     <> exeExt
+  let destPath = inst </> destFileName
+  handleIO (throwE . CopyError . show) $ liftIO $ copyFile
+    (path </> stackFile <> exeExt)
+    destPath
+  lift $ chmod_755 destPath
 
 
     ---------------------
@@ -1704,6 +1777,7 @@ compileGHC :: ( MonadMask m
            -> [Text]                   -- ^ additional args to ./configure
            -> Maybe String             -- ^ build flavour
            -> Bool
+           -> Maybe FilePath           -- ^ isolate dir
            -> Excepts
                 '[ AlreadyInstalled
                  , BuildFailed
@@ -1716,13 +1790,14 @@ compileGHC :: ( MonadMask m
                  , UnknownArchive
                  , TarDirDoesNotExist
                  , NotInstalled
+                 , DirNotEmpty
 #if !defined(TAR)
                  , ArchiveResult
 #endif
                  ]
                 m
                 GHCTargetVersion
-compileGHC targetGhc ov bstrap jobs mbuildConfig patchdir aargs buildFlavour hadrian
+compileGHC targetGhc ov bstrap jobs mbuildConfig patchdir aargs buildFlavour hadrian isolateDir
   = do
     PlatformRequest { .. } <- lift getPlatformReq
     GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
@@ -1792,12 +1867,18 @@ compileGHC targetGhc ov bstrap jobs mbuildConfig patchdir aargs buildFlavour had
     alreadyInstalled <- lift $ ghcInstalled installVer
     alreadySet <- fmap (== Just tver) $ lift $ ghcSet (_tvTarget tver)
     when alreadyInstalled $ do
-      lift $ $(logWarn) [i|GHC #{prettyShow tver} already installed. Will overwrite existing version.|]
+      case isolateDir of
+        Just isoDir ->
+          lift $ $(logWarn) [i|GHC #{prettyShow tver} already installed. Isolate installing to #{isoDir} |]
+        Nothing ->
+          lift $ $(logWarn) [i|GHC #{prettyShow tver} 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         <- lift $ ghcupGHCDir installVer
+    ghcdir <- case isolateDir of
+      Just isoDir -> pure isoDir
+      Nothing -> lift $ ghcupGHCDir installVer
 
     bghc <- case bstrap of
       Right g    -> pure $ Right g
@@ -1814,9 +1895,14 @@ compileGHC targetGhc ov bstrap jobs mbuildConfig patchdir aargs buildFlavour had
         pure (b, bmk)
       )
 
-    when alreadyInstalled $ do
-      lift $ $(logInfo) [i|Deleting existing installation|]
-      liftE $ rmGHCVer tver
+    case isolateDir of
+      Nothing ->
+        -- only remove old ghc in regular installs
+        when alreadyInstalled $ do
+          lift $ $(logInfo) [i|Deleting existing installation|]
+          liftE $ rmGHCVer tver
+          
+      _ -> pure ()
 
     forM_ mBindist $ \bindist -> do
       liftE $ installPackedGHC bindist
@@ -1825,11 +1911,15 @@ compileGHC targetGhc ov bstrap jobs mbuildConfig patchdir aargs buildFlavour had
                                (tver ^. tvVersion)
 
     liftIO $ B.writeFile (ghcdir </> ghcUpSrcBuiltFile) bmk
-
-    reThrowAll GHCupSetError $ postGHCInstall tver
-
-    -- restore
-    when alreadySet $ liftE $ void $ setGHC tver SetGHCOnly
+    
+    case isolateDir of
+      -- set and make symlinks for regular (non-isolated) installs
+      Nothing -> do
+        reThrowAll GHCupSetError $ postGHCInstall tver
+        -- restore
+        when alreadySet $ liftE $ void $ setGHC tver SetGHCOnly
+        
+      _ -> pure ()
 
     pure tver
 
@@ -2037,7 +2127,7 @@ endif|]
         liftIO $ threadDelay 5000000
 
   addBuildFlavourToConf bc = case buildFlavour of
-    Just bf -> [i|BuildFlavour = #{bf}|] <> [s|
+    Just bf -> [i|BuildFlavour = #{bf}
 |] <> [i|#{bc}|]
     Nothing -> bc
 
@@ -2189,6 +2279,7 @@ upgradeGHCup mtarget force' = do
     -------------
 
 
+
 -- | Creates @ghc-x.y.z@ and @ghc-x.y@ symlinks. This is used for
 -- both installing from source and bindist.
 postGHCInstall :: ( MonadReader env m

lib/GHCup/Download.hs

@@ -172,21 +172,31 @@ getBase :: ( MonadReader env m
         -> Excepts '[JSONError] m GHCupInfo
 getBase uri = do
   Settings { noNetwork } <- lift getSettings
-  yaml <- lift $ yamlFromCache uri
-  unless noNetwork $
-    handleIO (\e -> warnCache (displayException e))
-      . catchE @_ @_ @'[] (\e@(DownloadFailed _) -> warnCache (prettyShow e))
-      . reThrowAll @_ @_ @'[DownloadFailed] DownloadFailed
-      . smartDl
-      $ uri
+
+  -- try to download yaml... usually this writes it into cache dir,
+  -- but in some cases not (e.g. when using file://), so we honour
+  -- the return filepath, if any
+  mYaml <- if noNetwork && view (uriSchemeL' % schemeBSL') uri /= "file" -- for file://, let it fall through
+           then pure Nothing
+           else handleIO (\e -> warnCache (displayException e) >> pure Nothing)
+               . catchE @_ @_ @'[] (\e@(DownloadFailed _) -> warnCache (prettyShow e) >> pure Nothing)
+               . reThrowAll @_ @_ @'[DownloadFailed] DownloadFailed
+               . fmap Just
+               . smartDl
+               $ uri
+
+  -- if we didn't get a filepath from the download, use the cached yaml
+  actualYaml <- maybe (lift $ yamlFromCache uri) pure mYaml
+  lift $ $(logDebug) [i|Decoding yaml at: #{actualYaml}|]
+
   liftE
-    . onE_ (onError yaml)
+    . onE_ (onError actualYaml)
     . lEM' @_ @_ @'[JSONError] JSONDecodeError
     . fmap (first (\e -> [i|#{displayException e}
-Consider removing "#{yaml}" manually.|]))
+Consider removing "#{actualYaml}" manually.|]))
     . liftIO
     . Y.decodeFileEither
-    $ yaml
+    $ actualYaml
  where
   -- On error, remove the etags file and set access time to 0. This should ensure the next invocation
   -- may re-download and succeed.
@@ -221,28 +231,32 @@ Consider removing "#{yaml}" manually.|]))
                 , DigestError
                 ]
                m1
-               ()
+               FilePath
   smartDl uri' = do
     json_file <- lift $ yamlFromCache uri'
+    let scheme = view (uriSchemeL' % schemeBSL') uri'
     e <- liftIO $ doesFileExist json_file
     currentTime <- liftIO getCurrentTime
-    if e
-      then do
-        accessTime <- liftIO $ getAccessTime json_file
+    Dirs { cacheDir } <- lift getDirs
 
-        -- access time won't work on most linuxes, but we can try regardless
-        when ((utcTimeToPOSIXSeconds currentTime - utcTimeToPOSIXSeconds accessTime) > 300) $
-          -- no access in last 5 minutes, re-check upstream mod time
-          dlWithMod currentTime json_file
-      else
-        dlWithMod currentTime json_file
+       -- for local files, let's short-circuit and ignore access time
+    if | scheme == "file" -> liftE $ download uri' Nothing cacheDir Nothing True
+       | e -> do
+          accessTime <- liftIO $ getAccessTime json_file
+
+          -- access time won't work on most linuxes, but we can try regardless
+          if | ((utcTimeToPOSIXSeconds currentTime - utcTimeToPOSIXSeconds accessTime) > 300) ->
+                -- no access in last 5 minutes, re-check upstream mod time
+                dlWithMod currentTime json_file
+             | otherwise -> pure json_file
+       | otherwise -> dlWithMod currentTime json_file
    where
     dlWithMod modTime json_file = do
       let (dir, fn) = splitFileName json_file
       f <- liftE $ download uri' Nothing dir (Just fn) True
       liftIO $ setModificationTime f modTime
       liftIO $ setAccessTime f modTime
- 
+      pure f
 
 
 getDownloadInfo :: ( MonadReader env m
@@ -304,27 +318,25 @@ download :: ( MonadReader env m
             )
          => URI
          -> Maybe T.Text      -- ^ expected hash
-         -> FilePath          -- ^ destination dir
+         -> FilePath          -- ^ destination dir (ignored for file:// scheme)
          -> Maybe FilePath    -- ^ optional filename
          -> Bool              -- ^ whether to read an write etags
          -> Excepts '[DigestError , DownloadFailed] m FilePath
 download uri eDigest dest mfn etags
   | scheme == "https" = dl
   | scheme == "http"  = dl
-  | scheme == "file"  = cp
+  | scheme == "file"  = do
+      let destFile' = T.unpack . decUTF8Safe $ path
+      lift $ $(logDebug) [i|using local file: #{destFile'}|]
+      forM_ eDigest (liftE . flip checkDigest destFile')
+      pure destFile'
   | otherwise = throwE $ DownloadFailed (variantFromValue UnsupportedScheme)
 
  where
   scheme = view (uriSchemeL' % schemeBSL') uri
-  cp     = do
-    -- destination dir must exist
-    liftIO $ createDirRecursive' dest
-    let fromFile = T.unpack . decUTF8Safe $ path
-    liftIO $ copyFile fromFile destFile
-    pure destFile
   dl = do
-    let uri' = decUTF8Safe (serializeURIRef' uri)
-    lift $ $(logInfo) [i|downloading: #{uri'}|]
+    destFile <- liftE . reThrowAll @_ @_ @'[DownloadFailed] DownloadFailed $ getDestFile
+    lift $ $(logInfo) [i|downloading: #{uri'} as file #{destFile}|]
 
     -- destination dir must exist
     liftIO $ createDirRecursive' dest
@@ -366,7 +378,7 @@ download uri eDigest dest mfn etags
                             _ -> liftE $ throwE @_ @'[DownloadFailed] (DownloadFailed (toVariantAt @0 (MalformedHeaders headers)
                               :: V '[MalformedHeaders]))
 
-                          writeEtags (parseEtags headers)
+                          writeEtags destFile (parseEtags headers)
                     else
                       liftE $ lEM @_ @'[ProcessError] $ exec "curl" 
                         (o' ++ ["-fL", "-o", destFile, T.unpack uri']) Nothing Nothing
@@ -383,13 +395,13 @@ download uri eDigest dest mfn etags
                         case _exitCode of
                           ExitSuccess -> do
                             liftIO $ copyFile destFileTemp destFile
-                            writeEtags (parseEtags (decUTF8Safe' _stdErr))
+                            writeEtags destFile (parseEtags (decUTF8Safe' _stdErr))
                           ExitFailure i'
                             | i' == 8
                             , Just _ <- find (T.pack "304 Not Modified" `T.isInfixOf`) . T.lines . decUTF8Safe' $ _stdErr
                                      -> do
                                           $logDebug "Not modified, skipping download"
-                                          writeEtags (parseEtags (decUTF8Safe' _stdErr))
+                                          writeEtags destFile (parseEtags (decUTF8Safe' _stdErr))
                             | otherwise -> throwE (NonZeroExit i' "wget" opts)
                       else do
                         let opts = o' ++ ["-O", destFileTemp , T.unpack uri']
@@ -404,10 +416,10 @@ download uri eDigest dest mfn etags
                       let addHeaders = maybe mempty (\etag -> M.fromList [ (mk . E.encodeUtf8 . T.pack $ "If-None-Match"
                                                                          , E.encodeUtf8 etag)]) metag
                       liftE
-                        $ catchE @HTTPNotModified @'[DownloadFailed] @'[] (\(HTTPNotModified etag) -> lift $ writeEtags (pure $ Just etag))
+                        $ catchE @HTTPNotModified @'[DownloadFailed] @'[] (\(HTTPNotModified etag) -> lift $ writeEtags destFile (pure $ Just etag))
                         $ do
                           r <- downloadToFile https host fullPath port destFile addHeaders
-                          writeEtags (pure $ decUTF8Safe <$> getHeader r "etag")
+                          writeEtags destFile (pure $ decUTF8Safe <$> getHeader r "etag")
                     else void $ liftE $ catchE @HTTPNotModified
                                         @'[DownloadFailed]
                                    (\e@(HTTPNotModified _) ->
@@ -420,12 +432,18 @@ download uri eDigest dest mfn etags
 
 
   -- Manage to find a file we can write the body into.
-  destFile :: FilePath
-  destFile = maybe (dest </> T.unpack (decUTF8Safe (urlBaseName path)))
-                  (dest </>)
-                  mfn
+  getDestFile :: Monad m => Excepts '[NoUrlBase] m FilePath
+  getDestFile = 
+    case mfn of
+        Just fn -> pure (dest </> fn)
+        Nothing
+          | let urlBase = T.unpack (decUTF8Safe (urlBaseName path))
+          , not (null urlBase) -> pure (dest </> urlBase)
+          -- TODO: remove this once we use hpath again
+          | otherwise -> throwE $ NoUrlBase uri'
 
   path = view pathL' uri
+  uri' = decUTF8Safe (serializeURIRef' uri)
 
   parseEtags :: (MonadLogger m, MonadIO m, MonadThrow m) => T.Text -> m (Maybe T.Text)
   parseEtags stderr = do
@@ -444,8 +462,8 @@ download uri eDigest dest mfn etags
         $logDebug "No etags header found"
         pure Nothing
 
-  writeEtags :: (MonadLogger m, MonadIO m, MonadThrow m) => m (Maybe T.Text) -> m ()
-  writeEtags getTags = do
+  writeEtags :: (MonadLogger m, MonadIO m, MonadThrow m) => FilePath -> m (Maybe T.Text) -> m ()
+  writeEtags destFile getTags = do
     getTags >>= \case
       Just t -> do
         $logDebug [i|Writing etagsFile #{(etagsFile destFile)}|]

lib/GHCup/Errors.hs

@@ -134,6 +134,13 @@ instance Pretty AlreadyInstalled where
   pPrint (AlreadyInstalled tool ver') =
     text [i|#{tool}-#{prettyShow ver'} is already installed|]
 
+-- | The Directory is supposed to be empty, but wasn't.
+data DirNotEmpty = DirNotEmpty {path :: FilePath}
+
+instance Pretty DirNotEmpty where
+  pPrint (DirNotEmpty path) = do
+    text [i|The directory was expected to be empty, but isn't: #{path}|]
+
 -- | The tool is not installed. Some operations rely on a tool
 -- to be installed (such as setting the current GHC version).
 data NotInstalled = NotInstalled Tool GHCTargetVersion
@@ -168,6 +175,16 @@ instance Pretty FileDoesNotExistError where
   pPrint (FileDoesNotExistError file) =
     text [i|File "#{file}" does not exist.|]
 
+-- | The file already exists
+-- (e.g. when we use isolated installs with the same path).
+-- (e.g. This is done to prevent any overwriting)
+data FileAlreadyExistsError = FileAlreadyExistsError FilePath
+  deriving Show
+
+instance Pretty FileAlreadyExistsError where
+  pPrint (FileAlreadyExistsError file) =
+    text [i|File "#{file}" Already exists.|]
+
 data TarDirDoesNotExist = TarDirDoesNotExist TarDir
   deriving Show
 
@@ -327,6 +344,15 @@ instance Pretty UnexpectedListLength where
 
 instance Exception UnexpectedListLength
 
+data NoUrlBase = NoUrlBase Text
+  deriving Show
+
+instance Pretty NoUrlBase where
+  pPrint (NoUrlBase url) =
+    text [i|Couldn't get a base filename from url #{url}|]
+
+instance Exception NoUrlBase
+
 
 
     ------------------------

lib/GHCup/Types.hs

@@ -304,6 +304,41 @@ data UserSettings = UserSettings
 defaultUserSettings :: UserSettings
 defaultUserSettings = UserSettings Nothing Nothing Nothing Nothing Nothing Nothing Nothing Nothing
 
+fromSettings :: Settings -> Maybe KeyBindings -> UserSettings
+fromSettings Settings{..} Nothing =
+  UserSettings {
+      uCache = Just cache
+    , uNoVerify = Just noVerify
+    , uVerbose = Just verbose
+    , uKeepDirs = Just keepDirs
+    , uDownloader = Just downloader
+    , uNoNetwork = Just noNetwork
+    , uKeyBindings = Nothing
+    , uUrlSource = Just urlSource
+  }
+fromSettings Settings{..} (Just KeyBindings{..}) =
+  let ukb = UserKeyBindings
+            { kUp           = Just bUp        
+            , kDown         = Just bDown      
+            , kQuit         = Just bQuit      
+            , kInstall      = Just bInstall   
+            , kUninstall    = Just bUninstall 
+            , kSet          = Just bSet       
+            , kChangelog    = Just bChangelog 
+            , kShowAll      = Just bShowAllVersions
+            , kShowAllTools = Just bShowAllTools
+            }
+  in UserSettings {
+      uCache = Just cache
+    , uNoVerify = Just noVerify
+    , uVerbose = Just verbose
+    , uKeepDirs = Just keepDirs
+    , uDownloader = Just downloader
+    , uNoNetwork = Just noNetwork
+    , uKeyBindings = Just ukb
+    , uUrlSource = Just urlSource
+  }
+
 data UserKeyBindings = UserKeyBindings
   { kUp        :: Maybe Key
   , kDown      :: Maybe Key

lib/GHCup/Types/JSON.hs

@@ -316,3 +316,6 @@ deriveJSON 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