Fix tests

https://github.com/haskell-infra/www.haskell.org/pull/88

CHANGELOG.md

@@ -1,10 +1,16 @@
 # Revision history for ghcup
 
-## 0.1.17.6 -- ????-??-??
+## 0.1.17.6 -- 2022-03-18
 
 * Vastly improve shell completions wrt [#242](https://gitlab.haskell.org/haskell/ghcup-hs/-/merge_requests/242)
 * Fix 'ghcup install cabal/hls/stack --set' wrt [#324](https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/324)
 * Fix bad error message wrt [#323](https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/323)
+* Use predictable /tmp names for `ghcup run`, fixes [#329](https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/329)
+* Fix bug with isolated installation of not previously installed versions
+* Add `--no-set` to install commands, fixes [#330](https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/330)
+* Fix serious bug in `ghcup list --raw-format -t <tool> -c installed`
+* Overhaul metadata merging and add `ghcup config add-release-channel URI` wrt [#328](https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/328)
+* Fix max path issues on windows with `ghcup run`
 
 ## 0.1.17.5 -- 2022-02-26
 

app/ghcup/GHCup/OptParse/Config.hs

@@ -7,6 +7,7 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE DuplicateRecordFields #-}
 {-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ExplicitForAll #-}
 
 module GHCup.OptParse.Config where
 
@@ -17,6 +18,7 @@ import           GHCup.Utils
 import           GHCup.Utils.Prelude
 import           GHCup.Utils.Logger
 import           GHCup.Utils.String.QQ
+import           GHCup.OptParse.Common
 
 #if !MIN_VERSION_base(4,13,0)
 import           Control.Monad.Fail             ( MonadFail )
@@ -27,10 +29,11 @@ import           Control.Monad.Trans.Resource
 import           Data.Functor
 import           Data.Maybe
 import           Haskus.Utils.Variant.Excepts
-import           Options.Applicative     hiding ( style )
+import           Options.Applicative     hiding ( style, ParseError )
 import           Options.Applicative.Help.Pretty ( text )
 import           Prelude                 hiding ( appendFile )
 import           System.Exit
+import           URI.ByteString          hiding ( uriParser )
 
 import qualified Data.Text                     as T
 import qualified Data.ByteString.UTF8          as UTF8
@@ -49,6 +52,7 @@ data ConfigCommand
   = ShowConfig
   | SetConfig String (Maybe String)
   | InitConfig
+  | AddReleaseChannel URI
 
 
 
@@ -62,6 +66,7 @@ configP = subparser
       (  command "init" initP
       <> command "set"  setP -- [set] KEY VALUE at help lhs
       <> command "show" showP
+      <> command "add-release-channel" addP
       )
     <|> argsP -- add show for a single option
     <|> pure ShowConfig
@@ -70,6 +75,8 @@ configP = subparser
   showP = info (pure ShowConfig) (progDesc "Show current config (default)")
   setP  = info argsP (progDesc "Set config KEY to VALUE (or specify as single json value)" <> footerDoc (Just $ text configSetFooter))
   argsP = SetConfig <$> argument str (metavar "<JSON_VALUE | YAML_KEY>") <*> optional (argument str (metavar "YAML_VALUE"))
+  addP  = info (AddReleaseChannel <$> argument (eitherReader uriParser) (metavar "URI" <> completer fileUri))
+    (progDesc "Add a release channel from a URI")
 
 
 
@@ -114,23 +121,18 @@ formatConfig :: UserSettings -> String
 formatConfig = UTF8.toString . Y.encode
 
 
-updateSettings :: Monad m => UTF8.ByteString -> Settings -> Excepts '[JSONError] m Settings
-updateSettings config' settings = do
-  settings' <- lE' (JSONDecodeError . displayException) . Y.decodeEither' $ config'
-  pure $ mergeConf settings' settings
-  where
-   mergeConf :: UserSettings -> Settings -> Settings
-   mergeConf UserSettings{..} Settings{..} =
-     let cache'      = fromMaybe cache uCache
-         metaCache'  = fromMaybe metaCache uMetaCache
-         noVerify'   = fromMaybe noVerify uNoVerify
-         keepDirs'   = fromMaybe keepDirs uKeepDirs
-         downloader' = fromMaybe downloader uDownloader
-         verbose'    = fromMaybe verbose uVerbose
-         urlSource'  = fromMaybe urlSource uUrlSource
-         noNetwork'  = fromMaybe noNetwork uNoNetwork
-         gpgSetting' = fromMaybe gpgSetting uGPGSetting
-     in Settings cache' metaCache' noVerify' keepDirs' downloader' verbose' urlSource' noNetwork' gpgSetting' noColor
+updateSettings :: UserSettings -> Settings -> Settings
+updateSettings UserSettings{..} Settings{..} =
+   let cache'      = fromMaybe cache uCache
+       metaCache'  = fromMaybe metaCache uMetaCache
+       noVerify'   = fromMaybe noVerify uNoVerify
+       keepDirs'   = fromMaybe keepDirs uKeepDirs
+       downloader' = fromMaybe downloader uDownloader
+       verbose'    = fromMaybe verbose uVerbose
+       urlSource'  = fromMaybe urlSource uUrlSource
+       noNetwork'  = fromMaybe noNetwork uNoNetwork
+       gpgSetting' = fromMaybe gpgSetting uGPGSetting
+   in Settings cache' metaCache' noVerify' keepDirs' downloader' verbose' urlSource' noNetwork' gpgSetting' noColor
 
 
 
@@ -140,7 +142,7 @@ updateSettings config' settings = do
 
 
 
-config :: ( Monad m
+config :: forall m. ( Monad m
           , MonadMask m
           , MonadUnliftIO m
           , MonadFail m
@@ -161,27 +163,42 @@ config configCommand settings keybindings runLogger = case configCommand of
     liftIO $ putStrLn $ formatConfig $ fromSettings settings (Just keybindings)
     pure ExitSuccess
 
-  (SetConfig k (Just v)) ->
-    case v of
-      "" -> do
-        runLogger $ logError "Empty values are not allowed"
-        pure $ ExitFailure 55
-      _  -> doConfig (k <> ": " <> v <> "\n")
+  (SetConfig k mv) -> do
+    r <- runE @'[JSONError, ParseError] $ do
+      case mv of
+        Just "" ->
+          throwE $ ParseError "Empty values are not allowed"
+        Nothing -> do
+          usersettings <- decodeSettings k
+          lift $ doConfig usersettings
+          pure ()
+        Just v -> do
+          usersettings <- decodeSettings (k <> ": " <> v <> "\n")
+          lift $ doConfig usersettings
+          pure ()
+    case r of
+      VRight _ -> pure ExitSuccess
+      VLeft (V (JSONDecodeError e)) -> do
+        runLogger $ logError $ "Error decoding config: " <> T.pack e
+        pure $ ExitFailure 65
+      VLeft _ -> pure $ ExitFailure 65
 
-  (SetConfig json Nothing) -> doConfig json
+  AddReleaseChannel uri -> do
+    case urlSource settings of
+      AddSource xs -> do
+        doConfig (defaultUserSettings { uUrlSource = Just $ AddSource (xs <> [Right uri]) })
+        pure ExitSuccess
+      _ -> do
+        doConfig (defaultUserSettings { uUrlSource = Just $ AddSource [Right uri] })
+        pure ExitSuccess
 
  where
-  doConfig val = do
-    r <- runE @'[JSONError] $ do
-      settings' <- updateSettings (UTF8.fromString val) settings
-      path <- liftIO getConfigFilePath
-      liftIO $ writeFile path $ formatConfig $ fromSettings settings' (Just keybindings)
-      lift $ runLogger $ logDebug $ T.pack $ show settings'
-      pure ()
+  doConfig :: MonadIO m => UserSettings -> m ()
+  doConfig usersettings = do
+    let settings' = updateSettings usersettings 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 $ "Error decoding config: " <> T.pack e
-          pure $ ExitFailure 65
-        VLeft _ -> pure $ ExitFailure 65
+  decodeSettings = lE' (JSONDecodeError . displayException) . Y.decodeEither' . UTF8.fromString

app/ghcup/GHCup/OptParse/List.hs

@@ -143,11 +143,11 @@ printListResult no_color raw lr = do
             )
         $ lr
   let cols =
-        foldr (\xs ys -> zipWith (:) xs ys) (cycle [[]]) rows
+        foldr (\xs ys -> zipWith (:) xs ys) (repeat []) rows
       lengths = fmap (maximum . fmap strWidth) cols
       padded  = fmap (\xs -> zipWith padTo xs lengths) rows
 
-  forM_ padded $ \row -> putStrLn $ unwords row
+  forM_ (if raw then rows else padded) $ \row -> putStrLn $ unwords row
  where
 
   padTo str' x =

app/ghcup/GHCup/OptParse/Run.hs

@@ -15,7 +15,7 @@ import           GHCup.Utils.File
 import           GHCup.OptParse.Common
 import           GHCup.Errors
 import           GHCup.Types
-import           GHCup.Types.Optics             ( getDirs )
+import           GHCup.Types.Optics
 import           GHCup.Utils.Logger
 import           GHCup.Utils.String.QQ
 
@@ -187,14 +187,16 @@ runLeanRUN leanAppstate =
       @RunEffects
 
 runRUN :: MonadUnliftIO m
-      => (ReaderT AppState m (VEither RunEffects a) -> m (VEither RunEffects a))
+      => IO AppState
       -> Excepts RunEffects (ResourceT (ReaderT AppState m)) a
       -> m (VEither RunEffects a)
-runRUN runAppState =
-  runAppState
+runRUN appState action' = do
+  s' <- liftIO appState
+  flip runReaderT s'
     . runResourceT
     . runE
       @RunEffects
+    $ action'
 
 
 
@@ -212,52 +214,77 @@ run :: forall m.
        , MonadUnliftIO m
        )
    => RunOptions
-   -> (forall a. ReaderT AppState m (VEither RunEffects a) -> m (VEither RunEffects a))
+   -> IO AppState
    -> LeanAppState
    -> (ReaderT LeanAppState m () -> m ())
    -> m ExitCode
-run RunOptions{..} runAppState leanAppstate runLogger = runE @RunEffects ( do
-   toolchain <- Excepts resolveToolchain
-   tmp <- case runBinDir of
-     Just bindir -> do
-       liftIO $ createDirRecursive' bindir
-       liftIO $ canonicalizePath bindir
-     Nothing -> do
-       d <- liftIO $ predictableTmpDir toolchain
-       liftIO $ createDirRecursive' d
-       liftIO $ canonicalizePath d
-   Excepts $ installToolChain toolchain tmp
-   pure tmp
-   ) >>= \case
-     VRight tmp -> do
-       case runCOMMAND of
-         [] -> do
-           liftIO $ putStr tmp
-           pure ExitSuccess
-         (cmd:args) -> do
-           newEnv <- liftIO $ addToPath tmp
+run RunOptions{..} runAppState leanAppstate runLogger = do
+   r <- if or (fmap (maybe False isToolTag) [runGHCVer, runCabalVer, runHLSVer, runStackVer]) || runInstTool'
+        then runRUN runAppState $ do
+         toolchain <- liftE resolveToolchainFull
+         tmp <- case runBinDir of
+           Just bindir -> do
+             liftIO $ createDirRecursive' bindir
+             liftIO $ canonicalizePath bindir
+           Nothing -> do
+             d <- liftIO $ predictableTmpDir toolchain
+             liftIO $ createDirRecursive' d
+             liftIO $ canonicalizePath d
+         liftE $ installToolChainFull toolchain tmp
+         pure tmp
+        else runLeanRUN leanAppstate $ do
+         toolchain <- resolveToolchain
+         tmp <- case runBinDir of
+           Just bindir -> do
+             liftIO $ createDirRecursive' bindir
+             liftIO $ canonicalizePath bindir
+           Nothing -> do
+             d <- liftIO $ predictableTmpDir toolchain
+             liftIO $ createDirRecursive' d
+             liftIO $ canonicalizePath d
+         liftE $ installToolChain toolchain tmp
+         pure tmp
+   case r of
+         VRight tmp -> do
+           case runCOMMAND of
+             [] -> do
+               liftIO $ putStr tmp
+               pure ExitSuccess
+             (cmd:args) -> do
+               newEnv <- liftIO $ addToPath tmp
 #ifndef IS_WINDOWS
-           void $ liftIO $ SPP.executeFile cmd True args (Just newEnv)
-           pure ExitSuccess
+               void $ liftIO $ SPP.executeFile cmd True args (Just newEnv)
+               pure ExitSuccess
 #else
-           r' <- runLeanRUN leanAppstate $ liftE $ lEM @_ @'[ProcessError] $ exec cmd args Nothing (Just newEnv)
-           case r' of
-             VRight _ -> pure ExitSuccess
-             VLeft e -> do
-               runLogger $ logError $ T.pack $ prettyShow e
-               pure $ ExitFailure 28
+               r' <- runLeanRUN leanAppstate $ liftE $ lEM @_ @'[ProcessError] $ exec cmd args Nothing (Just newEnv)
+               case r' of
+                 VRight _ -> pure ExitSuccess
+                 VLeft e -> do
+                   runLogger $ logError $ T.pack $ prettyShow e
+                   pure $ ExitFailure 28
 #endif
-     VLeft e -> do
-       runLogger $ logError $ T.pack $ prettyShow e
-       pure $ ExitFailure 27
+         VLeft e -> do
+           runLogger $ logError $ T.pack $ prettyShow e
+           pure $ ExitFailure 27
+
   where
+
    isToolTag :: ToolVersion -> Bool
    isToolTag (ToolTag _) = True
    isToolTag _           = False
 
    -- TODO: doesn't work for cross
-   resolveToolchain
-     | or (fmap (maybe False isToolTag) [runGHCVer, runCabalVer, runHLSVer, runStackVer]) || runInstTool' = runRUN runAppState $ do
+   resolveToolchainFull :: ( MonadFail m
+                           , MonadThrow m
+                           , MonadIO m
+                           , MonadCatch m
+                           )
+                        => Excepts
+                             '[ TagNotFound
+                              , NextVerNotFound
+                              , NoToolVersionSet
+                              ] (ResourceT (ReaderT AppState m)) Toolchain
+   resolveToolchainFull = do
          ghcVer <- forM runGHCVer $ \ver -> do
            (v, _) <- liftE $ fromVersion (Just ver) GHC
            pure v
@@ -271,7 +298,8 @@ run RunOptions{..} runAppState leanAppstate runLogger = runE @RunEffects ( do
            (v, _) <- liftE $ fromVersion (Just ver) Stack
            pure v
          pure Toolchain{..}
-     | otherwise = runLeanRUN leanAppstate $ do
+
+   resolveToolchain = do
          ghcVer <- case runGHCVer of
             Just (ToolVersion v) -> pure $ Just v
             Nothing -> pure Nothing
@@ -290,8 +318,33 @@ run RunOptions{..} runAppState leanAppstate runLogger = runE @RunEffects ( do
             _ -> fail "Internal error"
          pure Toolchain{..}
 
-   installToolChain Toolchain{..} tmp
-     | or (fmap (maybe False isToolTag) [runGHCVer, runCabalVer, runHLSVer, runStackVer]) || runInstTool' = runRUN runAppState $ do
+   installToolChainFull :: ( MonadFail m
+                           , MonadThrow m
+                           , MonadIO m
+                           , MonadCatch m
+                           )
+                        => Toolchain
+                        -> FilePath
+                        -> Excepts
+                             '[ TagNotFound
+                              , NextVerNotFound
+                              , NoToolVersionSet
+                              , UnknownArchive
+                              , TarDirDoesNotExist
+                              , ProcessError
+                              , NotInstalled
+                              , NoDownload
+                              , GPGError
+                              , DownloadFailed
+                              , DirNotEmpty
+                              , DigestError
+                              , BuildFailed
+                              , ArchiveResult
+                              , AlreadyInstalled
+                              , FileAlreadyExistsError
+                              , CopyError
+                              ] (ResourceT (ReaderT AppState m)) ()
+   installToolChainFull Toolchain{..} tmp = do
          forM_ [(GHC,) <$> ghcVer, (Cabal,) <$> cabalVer, (HLS,) <$> hlsVer, (Stack,) <$> stackVer] $ \mt -> do
            isInstalled <- maybe (pure False) (\(tool, v) -> lift $ checkIfToolInstalled' tool v) mt
            case mt of
@@ -320,7 +373,16 @@ run RunOptions{..} runAppState leanAppstate runLogger = runE @RunEffects ( do
                  False
                setTool HLS v tmp
              _ -> pure ()
-     | otherwise = runLeanRUN leanAppstate $ do
+
+   installToolChain :: ( MonadFail m
+                       , MonadThrow m
+                       , MonadIO m
+                       , MonadCatch m
+                       )
+                    => Toolchain
+                    -> FilePath
+                    -> Excepts '[NotInstalled] (ReaderT LeanAppState m) ()
+   installToolChain Toolchain{..} tmp = do
          forM_ [(GHC,) <$> ghcVer, (Cabal,) <$> cabalVer, (HLS,) <$> hlsVer, (Stack,) <$> stackVer] $ \mt -> do
            case mt of
              Just (GHC, v)   -> setTool GHC v tmp

app/ghcup/Main.hs

@@ -82,7 +82,7 @@ toSettings options = do
          keepDirs    = fromMaybe (fromMaybe (Types.keepDirs defaultSettings) uKeepDirs) optKeepDirs
          downloader  = fromMaybe (fromMaybe defaultDownloader uDownloader) optsDownloader
          keyBindings = maybe defaultKeyBindings mergeKeys uKeyBindings
-         urlSource   = maybe (fromMaybe (Types.urlSource defaultSettings) uUrlSource) OwnSource optUrlSource
+         urlSource   = maybe (fromMaybe (Types.urlSource defaultSettings) uUrlSource) (OwnSource . (:[]) . Right) optUrlSource
          noNetwork   = fromMaybe (fromMaybe (Types.noNetwork defaultSettings) uNoNetwork) optNoNetwork
          gpgSetting  = fromMaybe (fromMaybe (Types.gpgSetting defaultSettings) uGPGSetting) optGpg
      in (Settings {..}, keyBindings)
@@ -235,7 +235,9 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                   Interactive -> pure ()
 #endif
                   -- check for new tools
-                  _ -> lookupEnv "GHCUP_SKIP_UPDATE_CHECK" >>= \case
+                  _
+                    | Just False <- optVerbose -> pure ()
+                    | otherwise -> lookupEnv "GHCUP_SKIP_UPDATE_CHECK" >>= \case
                          Nothing -> void . flip runReaderT s' . runE @'[TagNotFound, NextVerNotFound, NoToolVersionSet] $ do
                            newTools <- lift checkForUpdates 
                            forM_ newTools $ \newTool@(t, l) -> do
@@ -313,7 +315,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
             Nuke                     -> nuke appState runLogger
             Prefetch pfCom           -> prefetch pfCom runAppState runLogger
             GC gcOpts                -> gc gcOpts runAppState runLogger
-            Run runCommand           -> run runCommand runAppState leanAppstate runLogger
+            Run runCommand           -> run runCommand appState leanAppstate runLogger
 
           case res of
             ExitSuccess        -> pure ()

cabal.project

@@ -15,7 +15,9 @@ source-repository-package
 
 constraints: http-io-streams -brotli,
              any.Cabal ==3.6.2.0,
-             any.aeson >= 2.0.1.0
+             any.aeson >= 2.0.1.0,
+             -- https://github.com/typeable/generic-arbitrary/issues/14
+             any.generic-arbitrary < 0.2.1
 
 package libarchive
   flags: -system-libarchive

data/config.yaml

@@ -48,12 +48,16 @@ url-source:
 
   ## Example 1: Read download info from this location instead
   ## Accepts file/http/https scheme
+  ## Can also be an array of URLs or an array of 'Either GHCupInfo URL', in
+  ## which case they are merged right-biased (overwriting duplicate versions).
   # OwnSource: "file:///home/jule/git/ghcup-hs/ghcup-0.0.3.yaml"
 
-  ## Example 2: Add custom tarballs to the default downloads, overwriting duplicate versions
+  ## Example 2: Add custom tarballs to the default downloads, overwriting duplicate versions.
+  ## Can also be an array of 'Either GHCupInfo URL', also see Example 3.
   # AddSource:
     # Left:
-      # toolRequirements: {} # this is ignored
+      # globalTools: {}
+      # toolRequirements: {}
       # ghcupDownloads:
         # GHC:
           # 9.10.2:
@@ -66,6 +70,8 @@ url-source:
                     # dlSubdir: ghc-7.10.3
                     # dlHash: 01cfbad8dff1e8b34a5fdca8caeaf843b56e36af919e29cd68870d2588563db5
 
-  ## Example 3: Add a custom download file to the default downloads, overwriting duplicate versions
+  ## Example 3: Add multiple custom download files to the default downloads via right-biased merge (overwriting duplicate
+  ## versions).
   # AddSource:
-    # Right: "file:///home/jule/git/ghcup-hs/ghcup-custom.yaml"
+    # - Right: "file:///home/jule/git/ghcup-hs/ghcup-prereleases.yaml"
+    # - Right: "file:///home/jule/git/ghcup-hs/ghcup-custom.yaml"

docs/guide.md

@@ -1,6 +1,6 @@
 # User Guide
 
-`ghcup --help` is your friend.
+This is a more in-depth guide specific to GHCup. `ghcup --help` is your friend.
 
 ## Basic usage
 
@@ -43,13 +43,6 @@ All of the following are valid arguments to `ghcup install ghc`:
 
 If the argument is omitted, the default is `recommended`.
 
-## Configuration
-
-A configuration file can be put in `~/.ghcup/config.yaml`. The default config file
-explaining all possible configurations can be found in this repo: [config.yaml](https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/data/config.yaml).
-
-Partial configuration is fine. Command line options always override the config file settings.
-
 ## Manpages
 
 For man pages to work you need [man-db](http://man-db.nongnu.org/) as your `man` provider, then issue `man ghc`. Manpages only work for the currently set ghc.
@@ -64,6 +57,40 @@ as e.g. `/etc/bash_completion.d/ghcup` (depending on distro)
 and make sure your bashrc sources the startup script
 (`/usr/share/bash-completion/bash_completion` on some distros).
 
+# Configuration
+
+A configuration file can be put in `~/.ghcup/config.yaml`. The default config file
+explaining all possible configurations can be found in this repo: [config.yaml](https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/data/config.yaml).
+
+Partial configuration is fine. Command line options always override the config file settings.
+
+## Env variables
+
+This is the complete list of env variables that change GHCup behavior:
+
+* `GHCUP_USE_XDG_DIRS`: see [XDG support](#xdg-support) above
+* `TMPDIR`: where ghcup does the work (unpacking, building, ...)
+* `GHCUP_INSTALL_BASE_PREFIX`: the base of ghcup (default: `$HOME`)
+* `GHCUP_CURL_OPTS`: additional options that can be passed to curl
+* `GHCUP_WGET_OPTS`: additional options that can be passed to wget
+* `GHCUP_GPG_OPTS`: additional options that can be passed to gpg
+* `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
+
+### XDG support
+
+To enable XDG style directories, set the environment variable `GHCUP_USE_XDG_DIRS` to anything.
+
+Then you can control the locations via XDG environment variables as such:
+
+* `XDG_DATA_HOME`: GHCs will be unpacked in `ghcup/ghc` subdir (default: `~/.local/share`)
+* `XDG_CACHE_HOME`: logs and download files will be stored in `ghcup` subdir (default: `~/.cache`)
+* `XDG_BIN_HOME`: binaries end up here (default: `~/.local/bin`)
+* `XDG_CONFIG_HOME`: the config file is stored in `ghcup` subdir as `config.yaml` (default: `~/.config`)
+
+**Note that `ghcup` makes some assumptions about structure of files in `XDG_BIN_HOME`. So if you have other tools
+installing e.g. stack/cabal/ghc into it, this will likely clash. In that case consider disabling XDG support.**
+
 ## Caching
 
 GHCup has a few caching mechanisms to avoid redownloads. All cached files end up in `~/.ghcup/cache` by default.
@@ -83,6 +110,92 @@ have a 5 minutes cache per default depending on the last access time of the file
 
 If you experience problems, consider clearing the cache via `ghcup gc --cache`.
 
+## Metadata
+
+The metadata are the files that describe tool versions, where to download them etc. and
+can be viewed here: [https://github.com/haskell/ghcup-metadata](https://github.com/haskell/ghcup-metadata)
+
+### Mirrors
+
+GHCup allows to use custom mirrors/download-info hosted by yourself or 3rd parties.
+
+To use a mirror, set the following option in `~/.ghcup/config.yaml`:
+
+```yml
+url-source:
+  # Accepts file/http/https scheme
+  OwnSource: "https://some-url/ghcup-0.0.6.yaml"
+```
+
+See [config.yaml](https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/data/config.yaml)
+for more options.
+
+Alternatively you can do it via a cli switch:
+
+```sh
+ghcup --url-source=https://some-url/ghcup-0.0.6.yaml list
+```
+
+#### Known mirrors
+
+1. [https://mirror.sjtu.edu.cn/docs/ghcup](https://mirror.sjtu.edu.cn/docs/ghcup)
+
+### (Pre-)Release channels
+
+A release channel is basically just a metadata file location. You can add additional release
+channels that complement the default one, such as the **prerelease channel** like so:
+
+```sh
+ghcup config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.7.yaml
+```
+
+This will result in `~/.ghcup/config.yaml` to contain this record:
+
+```yml
+url-source:
+  AddSource:
+  - Right: https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.7.yaml
+```
+
+You can add as many channels as you like. They are combined under *Last*, so versions from the prerelease channel
+here overwrite the default ones, if any.
+
+To remove the channel, delete the entire `url-source` section or set it back to the default:
+
+```yml
+url-source:
+  GHCupURL: []
+```
+
+If you want to combine your release channel with a mirror, you'd do it like so:
+
+```yml
+url-source:
+  OwnSource:
+  # base metadata
+  - "https://mirror.sjtu.edu.cn/ghcup/yaml/ghcup/data/ghcup-0.0.6.yaml"
+  # prerelease channel
+  - "https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.7.yaml"
+```
+
+# More on installation
+
+## Installing custom bindists
+
+There are a couple of good use cases to install custom bindists:
+
+1. manually built bindists (e.g. with patches)
+    - example: `ghcup install ghc -u 'file:///home/mearwald/tmp/ghc-eff-patches/ghc-8.10.2-x86_64-deb10-linux.tar.xz' 8.10.2-eff`
+2. GHC head CI bindists
+    - example: `ghcup install ghc -u 'https://gitlab.haskell.org/api/v4/projects/1/jobs/artifacts/master/raw/ghc-x86_64-fedora27-linux.tar.xz?job=validate-x86_64-linux-fedora27' head`
+3. DWARF bindists
+    - example: `ghcup install ghc -u 'https://downloads.haskell.org/~ghc/8.10.2/ghc-8.10.2-x86_64-deb10-linux-dwarf.tar.xz' 8.10.2-dwarf`
+
+Since the version parser is pretty lax, `8.10.2-eff` and `head` are both valid versions
+and produce the binaries `ghc-8.10.2-eff` and `ghc-head` respectively.
+GHCup always needs to know which version the bindist corresponds to (this is not automatically
+detected).
+
 ## Compiling GHC from source
 
 Compiling from source is supported for both source tarballs and arbitrary git refs. See `ghcup compile ghc --help`
@@ -106,74 +219,6 @@ For distributions with non-standard locations of cross toolchain and
 libraries, this may need some tweaking of `build.mk` or configure args.
 See `ghcup compile ghc --help` for further information.
 
-## XDG support
-
-To enable XDG style directories, set the environment variable `GHCUP_USE_XDG_DIRS` to anything.
-
-Then you can control the locations via XDG environment variables as such:
-
-* `XDG_DATA_HOME`: GHCs will be unpacked in `ghcup/ghc` subdir (default: `~/.local/share`)
-* `XDG_CACHE_HOME`: logs and download files will be stored in `ghcup` subdir (default: `~/.cache`)
-* `XDG_BIN_HOME`: binaries end up here (default: `~/.local/bin`)
-* `XDG_CONFIG_HOME`: the config file is stored in `ghcup` subdir as `config.yaml` (default: `~/.config`)
-
-**Note that `ghcup` makes some assumptions about structure of files in `XDG_BIN_HOME`. So if you have other tools
-installing e.g. stack/cabal/ghc into it, this will likely clash. In that case consider disabling XDG support.**
-
-## Env variables
-
-This is the complete list of env variables that change GHCup behavior:
-
-* `GHCUP_USE_XDG_DIRS`: see [XDG support](#xdg-support) above
-* `TMPDIR`: where ghcup does the work (unpacking, building, ...)
-* `GHCUP_INSTALL_BASE_PREFIX`: the base of ghcup (default: `$HOME`)
-* `GHCUP_CURL_OPTS`: additional options that can be passed to curl
-* `GHCUP_WGET_OPTS`: additional options that can be passed to wget
-* `GHCUP_GPG_OPTS`: additional options that can be passed to gpg
-* `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
-
-## Installing custom bindists
-
-There are a couple of good use cases to install custom bindists:
-
-1. manually built bindists (e.g. with patches)
-    - example: `ghcup install ghc -u 'file:///home/mearwald/tmp/ghc-eff-patches/ghc-8.10.2-x86_64-deb10-linux.tar.xz' 8.10.2-eff`
-2. GHC head CI bindists
-    - example: `ghcup install ghc -u 'https://gitlab.haskell.org/api/v4/projects/1/jobs/artifacts/master/raw/ghc-x86_64-fedora27-linux.tar.xz?job=validate-x86_64-linux-fedora27' head`
-3. DWARF bindists
-    - example: `ghcup install ghc -u 'https://downloads.haskell.org/~ghc/8.10.2/ghc-8.10.2-x86_64-deb10-linux-dwarf.tar.xz' 8.10.2-dwarf`
-
-Since the version parser is pretty lax, `8.10.2-eff` and `head` are both valid versions
-and produce the binaries `ghc-8.10.2-eff` and `ghc-head` respectively.
-GHCup always needs to know which version the bindist corresponds to (this is not automatically
-detected).
-
-## Mirrors
-
-GHCup allows to use custom mirrors/download-info hosted by yourself or 3rd parties.
-
-To use a mirror, set the following option in `~/.ghcup/config.yaml`:
-
-```yml
-url-source:
-  # Accepts file/http/https scheme
-  OwnSource: "https://some-url/ghcup-0.0.6.yaml"
-```
-
-See [config.yaml](https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/data/config.yaml)
-for more options.
-
-Alternatively you can do it via a cli switch:
-
-```sh
-ghcup --url-source=https://some-url/ghcup-0.0.6.yaml list
-```
-
-### Known mirrors
-
-1. [https://mirror.sjtu.edu.cn/docs/ghcup](https://mirror.sjtu.edu.cn/docs/ghcup)
-
 ## Isolated installs
 
 Ghcup also enables you to install a tool (GHC, Cabal, HLS, Stack) at an isolated location of your choosing.
@@ -257,9 +302,9 @@ gpg-setting: GPGLax # GPGStrict | GPGLax | GPGNone
 In `GPGStrict` mode, ghcup will fail if verification fails. In `GPGLax` mode it will just print a warning.
 You can also pass the mode via `ghcup --gpg <strict|lax|none>`.
    
-## Tips and tricks
+# Tips and tricks
 
-### Execute command with certain GHC in PATH
+## ghcup run
 
 If you don't want to explicitly switch the active GHC all the time and are using
 tools that rely on the plain `ghc` binary, GHCup provides an easy way to execute

docs/index.md

@@ -17,6 +17,7 @@ hide:
 
 <div class="text-center main-buttons">
 <a href="install/" class="btn btn-primary" role="button">Getting Started</a>
+<a href="steps/" class="btn btn-primary" role="button">First steps</a>
 <a href="guide/" class="btn btn-primary" role="button">User Guide</a>
 </div>
 

docs/install.md

@@ -2,7 +2,7 @@
 
 GHCup makes it easy to install specific versions of GHC on GNU/Linux,
 macOS (aka Darwin), FreeBSD and Windows and can also bootstrap a fresh [Haskell developer environment](./install/#supported-tools) from scratch.
-It follows the unix UNIX philosophy of [do one thing and do it well](https://en.wikipedia.org/wiki/Unix_philosophy#Do_One_Thing_and_Do_It_Well). Similar in scope to [rustup](https://github.com/rust-lang-nursery/rustup.rs), [pyenv](https://github.com/pyenv/pyenv) and [jenv](http://www.jenv.be).
+It follows the UNIX philosophy of [do one thing and do it well](https://en.wikipedia.org/wiki/Unix_philosophy#Do_One_Thing_and_Do_It_Well). Similar in scope to [rustup](https://github.com/rust-lang-nursery/rustup.rs), [pyenv](https://github.com/pyenv/pyenv) and [jenv](http://www.jenv.be).
 
 ## Installation
 
@@ -22,6 +22,8 @@ For Windows, run this in a PowerShell session:
 Set-ExecutionPolicy Bypass -Scope Process -Force;[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.ServicePointManager]::SecurityProtocol -bor 3072;Invoke-Command -ScriptBlock ([ScriptBlock]::Create((Invoke-WebRequest https://www.haskell.org/ghcup/sh/bootstrap-haskell.ps1 -UseBasicParsing))) -ArgumentList $true
 ```
 
+There's also a [youtube video](https://www.youtube.com/watch?v=bB4fmQiUYPw) explaining installation on windows.
+
 If you want to know what these scripts do, check out the [source code at the repository](https://gitlab.haskell.org/haskell/ghcup-hs/-/tree/master/scripts/bootstrap). Advanced users may want to perform a [manual installation](#manual-install) and GPG verify the binaries.
 
 ### Which versions get installed?
@@ -32,105 +34,97 @@ GHCup has two main channels for every tool: **recommended** and **latest**. By d
 
 Also see [tags and shortcuts](../guide/#tags-and-shortcuts) for more information.
 
-## First steps
+## Next steps
 
-1. To get started with creating a Haskell project, follow the [Getting Started with Haskell and Cabal](https://cabal.readthedocs.io/en/stable/getting-started.html) guide
-2. To learn Haskell, try any of those:
-    - A beginner friendly [4-lectures course](https://github.com/haskell-beginners-2022/course-plan) with exercises (by [Kowainik](https://kowainik.github.io/))
-    - An in-depth university [CIS 194 Haskell course](https://www.cis.upenn.edu/~cis194/spring13/) including exercises (by [Brent Yorgey](https://byorgey.wordpress.com/))
-3. To learn more about Haskell Toolchain management, check out the [ghcup user guide](./guide.md)
+1. Follow the [First steps guide](../steps) on how to build a "Hello world" program, use `ghc`, run an interactive REPL and create a Haskell project
+2. To understand the difference and overlap of `stack` and `cabal`, read on [here](https://gist.github.com/merijn/8152d561fb8b011f9313c48d876ceb07)
+3. To learn Haskell proper check out the links at [How to learn Haskell proper](../steps#how-to-learn-haskell-proper)
+4. To learn more about Haskell Toolchain management, check out the [ghcup user guide](./guide.md)
 
 ## Uninstallation
 
 On linux, just run `ghcup nuke`, then make sure any ghcup added lines in your `~/.bashrc` (or similar) are removed.
 
-On windows, double-click on the `Uninstall Haskell.ps1` PowerShell script on your Desktop.
+On windows, right click on the `Uninstall Haskell.ps1` PowerShell script on your Desktop and select *Run with PowerShell*.
 
 ## Supported tools
 
 GHCup supports the following tools, which are also known as the **Haskell Toolchain**:
 
-<details>
-  <summary>Show all supported <a href='https://www.haskell.org/ghc/'>GHC</a> versions</summary>
-  
+<details> <summary>Show all supported <a href='https://www.haskell.org/ghc/'>GHC</a> versions</summary>
 <table>
 <thead><tr><th>GHC Version</th><th>Tags</th></tr></thead>
 <tbody>
-<tr><td>7.10.3</td><td>base-4.8.2.0</td></tr>
-<tr><td>8.0.2</td><td>base-4.9.1.0</td></tr>
-<tr><td>8.2.2</td><td>base-4.10.1.0</td></tr>
-<tr><td>8.4.1</td><td>base-4.11.0.0</td></tr>
-<tr><td>8.4.2</td><td>base-4.11.1.0</td></tr>
-<tr><td>8.4.3</td><td>base-4.11.1.0</td></tr>
-<tr><td>8.4.4</td><td>base-4.11.1.0</td></tr>
-<tr><td>8.6.1</td><td>base-4.12.0.0</td></tr>
-<tr><td>8.6.2</td><td>base-4.12.0.0</td></tr>
-<tr><td>8.6.3</td><td>base-4.12.0.0</td></tr>
-<tr><td>8.6.4</td><td>base-4.12.0.0</td></tr>
-<tr><td>8.6.5</td><td>base-4.12.0.0</td></tr>
-<tr><td>8.8.1</td><td>base-4.13.0.0</td></tr>
-<tr><td>8.8.2</td><td>base-4.13.0.0</td></tr>
-<tr><td>8.8.3</td><td>base-4.13.0.0</td></tr>
-<tr><td>8.8.4</td><td>base-4.13.0.0</td></tr>
-<tr><td>8.10.1</td><td>base-4.14.0.0</td></tr>
-<tr><td>8.10.2</td><td>base-4.14.1.0</td></tr>
-<tr><td>8.10.3</td><td>base-4.14.1.0</td></tr>
-<tr><td>8.10.4</td><td>base-4.14.1.0</td></tr>
-<tr><td>8.10.5</td><td>base-4.14.2.0</td></tr>
-<tr><td>8.10.6</td><td>base-4.14.3.0</td></tr>
-<tr><td>8.10.7</td><td><span style="color:green">recommended</span>, base-4.14.3.0</td></tr>
-<tr><td>9.0.1</td><td>base-4.15.0.0</td></tr>
-<tr><td>9.0.2</td><td>base-4.15.1.0</td></tr>
-<tr><td>9.2.1</td><td>base-4.16.0.0</td></tr>
 <tr><td>9.2.2</td><td><span style="color:blue">latest</span>, base-4.16.1.0</td></tr>
+<tr><td>9.2.1</td><td>base-4.16.0.0</td></tr>
+<tr><td>9.0.2</td><td>base-4.15.1.0</td></tr>
+<tr><td>9.0.1</td><td>base-4.15.0.0</td></tr>
+<tr><td>8.10.7</td><td><span style="color:green">recommended</span>, base-4.14.3.0</td></tr>
+<tr><td>8.10.6</td><td>base-4.14.3.0</td></tr>
+<tr><td>8.10.5</td><td>base-4.14.2.0</td></tr>
+<tr><td>8.10.4</td><td>base-4.14.1.0</td></tr>
+<tr><td>8.10.3</td><td>base-4.14.1.0</td></tr>
+<tr><td>8.10.2</td><td>base-4.14.1.0</td></tr>
+<tr><td>8.10.1</td><td>base-4.14.0.0</td></tr>
+<tr><td>8.8.4</td><td>base-4.13.0.0</td></tr>
+<tr><td>8.8.3</td><td>base-4.13.0.0</td></tr>
+<tr><td>8.8.2</td><td>base-4.13.0.0</td></tr>
+<tr><td>8.8.1</td><td>base-4.13.0.0</td></tr>
+<tr><td>8.6.5</td><td>base-4.12.0.0</td></tr>
+<tr><td>8.6.4</td><td>base-4.12.0.0</td></tr>
+<tr><td>8.6.3</td><td>base-4.12.0.0</td></tr>
+<tr><td>8.6.2</td><td>base-4.12.0.0</td></tr>
+<tr><td>8.6.1</td><td>base-4.12.0.0</td></tr>
+<tr><td>8.4.4</td><td>base-4.11.1.0</td></tr>
+<tr><td>8.4.3</td><td>base-4.11.1.0</td></tr>
+<tr><td>8.4.2</td><td>base-4.11.1.0</td></tr>
+<tr><td>8.4.1</td><td>base-4.11.0.0</td></tr>
+<tr><td>8.2.2</td><td>base-4.10.1.0</td></tr>
+<tr><td>8.0.2</td><td>base-4.9.1.0</td></tr>
+<tr><td>7.10.3</td><td>base-4.8.2.0</td></tr>
 </tbody>
 </table>
-
 </details>
 
-<details>
-  <summary>Show all supported <a href='https://cabal.readthedocs.io/en/stable/'>cabal-install</a> versions</summary>
-  <table>
+<details> <summary>Show all supported <a href='https://cabal.readthedocs.io/en/stable/'>cabal-install</a> versions</summary>
+<table>
 <thead><tr><th>Cabal Version</th><th>Tags</th></tr></thead>
 <tbody>
-<tr><td>2.4.1.0</td><td></td></tr>
-<tr><td>3.0.0.0</td><td></td></tr>
-<tr><td>3.2.0.0</td><td></td></tr>
-<tr><td>3.4.0.0</td><td></td></tr>
-<tr><td>3.4.1.0</td><td></td></tr>
-<tr><td>3.6.0.0</td><td></td></tr>
 <tr><td>3.6.2.0</td><td><span style="color:blue">latest</span>, <span style="color:green">recommended</span></td></tr>
+<tr><td>3.6.0.0</td><td></td></tr>
+<tr><td>3.4.1.0</td><td></td></tr>
+<tr><td>3.4.0.0</td><td></td></tr>
+<tr><td>3.2.0.0</td><td></td></tr>
+<tr><td>3.0.0.0</td><td></td></tr>
+<tr><td>2.4.1.0</td><td></td></tr>
 </tbody>
 </table>
-
 </details>
 
-<details>
-  <summary>Show all supported <a href='https://haskell-language-server.readthedocs.io/en/stable/'>HLS</a> versions</summary>
+<details> <summary>Show all supported <a href='https://haskell-language-server.readthedocs.io/en/stable/'>HLS</a> versions</summary>
 <table>
 <thead><tr><th>HLS Version</th><th>Tags</th></tr></thead>
 <tbody>
-<tr><td>1.1.0</td><td></td></tr>
-<tr><td>1.2.0</td><td></td></tr>
-<tr><td>1.3.0</td><td></td></tr>
-<tr><td>1.4.0</td><td></td></tr>
-<tr><td>1.5.0</td><td></td></tr>
-<tr><td>1.5.1</td><td></td></tr>
-<tr><td>1.6.0.0</td><td></td></tr>
 <tr><td>1.6.1.0</td><td><span style="color:blue">latest</span>, <span style="color:green">recommended</span></td></tr>
+<tr><td>1.6.0.0</td><td></td></tr>
+<tr><td>1.5.1</td><td></td></tr>
+<tr><td>1.5.0</td><td></td></tr>
+<tr><td>1.4.0</td><td></td></tr>
+<tr><td>1.3.0</td><td></td></tr>
+<tr><td>1.2.0</td><td></td></tr>
+<tr><td>1.1.0</td><td></td></tr>
 </tbody>
 </table>
 </details>
 
-<details>
-  <summary>Show all supported <a href='https://docs.haskellstack.org/en/stable/README/'>Stack</a> versions</summary>
+<details> <summary>Show all supported <a href='https://docs.haskellstack.org/en/stable/README/'>Stack</a> versions</summary>
 <table>
 <thead><tr><th>Stack Version</th><th>Tags</th></tr></thead>
 <tbody>
-<tr><td>2.5.1</td><td></td></tr>
-<tr><td>2.7.1</td><td></td></tr>
-<tr><td>2.7.3</td><td></td></tr>
 <tr><td>2.7.5</td><td><span style="color:blue">latest</span>, <span style="color:green">recommended</span></td></tr>
+<tr><td>2.7.3</td><td></td></tr>
+<tr><td>2.7.1</td><td></td></tr>
+<tr><td>2.5.1</td><td></td></tr>
 </tbody>
 </table>
 </details>

docs/steps.md

@@ -0,0 +1,346 @@
+# First steps
+
+In this guide we'll take a look at a few core tools that are installed
+with the Haskell toolchain, namely, `ghc`, `runghc` and `ghci`.
+These tools can be used to compile, interpret or explore Haskell programs.
+
+First, let's start by opening your system's command line interface
+and running `ghc --version` to make sure we have successfully
+installed a Haskell toolchain:
+
+```
+➜ ghc --version
+The Glorious Glasgow Haskell Compilation System, version 8.10.7
+```
+
+If this fails, consult [the Getting started page](../install) for information on
+how to install Haskell on your computer.
+
+## Compiling programs with ghc
+
+Running `ghc` invokes the Glasgow Haskell Compiler (GHC), and can be used to
+compile Haskell modules and programs into native executables and libraries.
+
+Create a new Haskell source file named `hello.hs`,
+and write the following code in it:
+
+```hs
+main = putStrLn "Hello, Haskell!"
+```
+
+Now, we can compile the program by invoking `ghc` with the file name:
+
+```sh
+➜ ghc hello.hs
+[1 of 1] Compiling Main             ( hello.hs, hello.o )
+Linking hello ...
+```
+
+For more in-depth information about the files `ghc` produces,
+follow the [GHC user guide](https://downloads.haskell.org/ghc/latest/docs/html/users_guide/using.html#getting-started-compiling-programs) guide.
+
+Now we run our program:
+
+```sh
+➜ ./hello 
+Hello, Haskell!
+```
+
+Alternatively, we can skip the compilation phase by using the command `runghc`:
+
+```sh
+➜ runghc hello.hs
+Hello, Haskell!
+```
+
+`runghc` interprets the source file instead of compiling it and does not
+create build artifacts. This makes it very useful when developing programs
+and can help accelerate the feedback loop. More information about `runghc`
+can be found in the
+[GHC user guide](https://downloads.haskell.org/ghc/latest/docs/html/users_guide/runghc.html).
+
+### Turning on warnings
+
+The `-Wall` flag will enable GHC to emit warnings about our code.
+
+```sh
+➜ ghc -Wall hello.hs -fforce-recomp
+[1 of 1] Compiling Main             ( hello.hs, hello.o )
+
+hello.hs:1:1: warning: [-Wmissing-signatures]
+    Top-level binding with no type signature: main :: IO ()
+  |
+1 | main = putStrLn "Hello, Haskell!"
+  | ^^^^
+Linking hello ...
+```
+
+While Haskell can infer
+the types of most expressions, it is recommended that top-level definitions
+are annotated with their types.
+
+Now our `hello.hs` source file should looks like this:
+
+```hs
+main :: IO ()
+main = putStrLn "Hello, world!"
+```
+
+And now GHC will compile `hello.hs` without warnings.
+
+## An interactive environment
+
+GHC provides an interactive environment in a form of a
+Read-Evaluate-Print Loop (REPL) called GHCi.
+To enter the environment run the program `ghci`.
+
+```sh
+➜ ghci
+GHCi, version 9.0.2: https://www.haskell.org/ghc/  :? for help
+ghci> 
+```
+
+It provides an interactive prompt where Haskell expressions can be written and
+evaluated.
+
+For example:
+
+```sh
+ghci> 1 + 1
+2
+ghci> putStrLn "Hello, world!"
+Hello, world!
+```
+
+We can define new names:
+
+```sh
+ghci> double x = x + x
+ghci> double 2
+4
+```
+
+We can write multi-line code by surrounding it with `:{` and `:}`:
+
+```hs
+ghci> :{
+| map f list =
+|     case list of
+|         [] -> []
+|         x : xs -> f x : map f xs
+| :}
+ghci> map (+1) [1, 2, 3]
+[2,3,4]
+
+```
+
+We can import Haskell source files using the `:load` command (`:l` for short):
+
+```sh
+ghci> :load hello.hs
+[1 of 1] Compiling Main             ( hello.hs, interpreted )
+Ok, one module loaded.
+ghci> main
+Hello, Haskell!
+```
+
+As well as import library modules:
+
+```sh
+ghci> import Data.Bits
+ghci> shiftL 32 1
+64
+ghci> clearBit 33 0
+32
+```
+
+We can even ask what the type of an expression is using the `:type` command
+(`:t` for short):
+
+```sh
+λ> :type putStrLn
+putStrLn :: String -> IO ()
+```
+
+To exit `ghci`, use the `:quit` command (or `:q` for short)
+
+```sh
+ghci> :quit
+Leaving GHCi.
+```
+
+A more thorough introduction to GHCi can be found in the
+[GHC user guide](https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/ghci.html).
+
+### Using external packages in ghci
+
+By default, GHCi can only load and use packages that are
+[included with the GHC installation](https://downloads.haskell.org/ghc/latest/docs/html/users_guide/9.2.2-notes.html#included-libraries).
+
+However, users of the [cabal-install](https://www.haskell.org/cabal) and
+[stack](http://haskellstack.org) build tools can download and load external packages
+very easily using the following commands:
+
+cabal-install:
+
+```sh
+cabal repl --build-depends async,say
+```
+
+Stack:
+
+```sh
+stack exec --package async --package say -- ghci
+```
+
+And the modules of the relevant packages will be available for import:
+
+```sh
+GHCi, version 9.0.1: https://www.haskell.org/ghc/  :? for help
+ghci> import Control.Concurrent.Async 
+ghci> import Say
+ghci> concurrently_ (sayString "Hello") (sayString "World")
+Hello
+World
+```
+
+Stack users can also use this feature with `runghc` and `ghc` by replacing
+`ghci` in the command above, and cabal-install users can generate an
+environment file that will make `async` and `say` visible for GHC tools
+in the current directory using this command:
+
+```sh
+cabal install --lib async say --package-env .
+```
+
+Many more packages are waiting for you on [Hackage](https://hackage.haskell.org).
+
+## Creating a proper package with modules
+
+The previous methods to compile Haskell code are for quick experiments and small
+programs. Usually in Haskell, we create cabal projects, where build tools such as
+`cabal-install` or `stack` will install necessary dependencies and compile modules
+in correct order. For simplicity's sake, this section will only use `cabal-install`.
+
+To get started, run:
+
+```sh
+mkdir haskell-project
+cd haskell-project
+cabal init --interactive
+```
+
+If you let it generate a simple project with sensible defaults, then you should have these files:
+
+* `src/MyLib.hs`: the library module of your project
+* `app/Main.hs`: the entry point of your project
+* `haskell-project.cabal`: the "cabal" file, describing your project, its dependencies and how it's built
+
+To build the project, run:
+
+```sh
+cabal build
+```
+
+To run the main executable, run:
+
+```sh
+➜ cabal run
+Hello, Haskell!
+someFunc
+```
+
+### Adding dependencies
+
+Now let's add a dependency and adjust our library module. Open `haskell-project.cabal`
+and find the library section:
+
+```
+library
+    exposed-modules:  MyLib
+
+    -- Modules included in this library but not exported.
+    -- other-modules:
+
+    -- LANGUAGE extensions used by modules in this package.
+    -- other-extensions:
+    build-depends:    base ^>=4.14.3.0
+    hs-source-dirs:   src
+    default-language: Haskell2010
+```
+
+The interesting parts here are `exposed-modules` and `build-depends`.
+To add a dependency, it should look like this:
+
+```
+    build-depends:    base ^>=4.14.3.0
+	                , directory
+```
+
+Now open `src/MyLib.hs` and change it to:
+
+```hs
+module MyLib (someFunc) where
+
+import System.Directory
+
+someFunc :: IO ()
+someFunc = do
+  contents <- listDirectory "src"
+  putStrLn (show contents)
+```
+
+### Adding modules
+
+To add a module to your package, adjust `exposed-modules`, like so
+
+```
+    exposed-modules:  MyLib
+	                  OtherLib
+```
+
+then create `src/OtherLib.hs` with the following contents:
+
+```hs
+module OtherLib where
+
+otherFunc :: String -> Int
+otherFunc str = length str
+```
+
+To use this function interactively, we can run:
+
+```sh
+➜ cabal repl
+ghci> import OtherLib
+ghci> otherFunc "Hello Haskell"
+13
+```
+
+For further information about how to manage Haskell projects
+see the [Cabal user guide](https://cabal.readthedocs.io/en/stable/getting-started.html).
+
+# Where to go from here
+
+<div class="text-center main-buttons">
+<a href="https://hackage.haskell.org/" class="btn btn-primary" role="button">Discover Haskell packages</a>
+<a href="https://hackage.haskell.org/package/base" class="btn btn-primary" role="button">The standard library</a>
+<a href="https://haskell-language-server.readthedocs.io/en/stable/installation.html" class="btn btn-primary" role="button">Editor setup with HLS</a>
+</div>
+
+## How to learn Haskell proper
+
+To learn Haskell, try any of those:
+
+- A beginner friendly [4-lectures course](https://github.com/haskell-beginners-2022/course-plan) with exercises (by [Kowainik](https://kowainik.github.io/))
+- An in-depth university [CIS 194 Haskell course](https://www.cis.upenn.edu/~cis194/spring13/) including exercises (by [Brent Yorgey](https://byorgey.wordpress.com/))
+
+## Projects to contribute to
+
+* [https://github.com/haskell/haskell-language-server](https://github.com/haskell/haskell-language-server)
+* [https://github.com/haskell/cabal](https://github.com/haskell/cabal)
+* [https://github.com/commercialhaskell/stack](https://github.com/commercialhaskell/stack)
+* [https://gitlab.haskell.org/haskell/ghcup-hs](https://gitlab.haskell.org/haskell/ghcup-hs)
+* [https://github.com/jgm/pandoc](https://github.com/jgm/pandoc)
+* [https://github.com/simonmichael/hledger](https://github.com/simonmichael/hledger)
+* [https://github.com/koalaman/shellcheck](https://github.com/koalaman/shellcheck)

ghcup.cabal

@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               ghcup
-version:            0.1.17.5
+version:            0.1.17.6
 license:            LGPL-3.0-only
 license-file:       LICENSE
 copyright:          Julian Ospald 2020

lib/GHCup/Download.hs

@@ -121,28 +121,25 @@ getDownloadsF = do
   Settings { urlSource } <- lift getSettings
   case urlSource of
     GHCupURL -> liftE $ getBase ghcupURL
-    (OwnSource url) -> liftE $ getBase url
+    (OwnSource exts) -> do
+      ext  <- liftE $ mapM (either pure getBase) exts
+      mergeGhcupInfo ext
     (OwnSpec av) -> pure av
-    (AddSource (Left ext)) -> do
+    (AddSource exts) -> do
       base <- liftE $ getBase ghcupURL
-      pure (mergeGhcupInfo base ext)
-    (AddSource (Right uri)) -> do
-      base <- liftE $ getBase ghcupURL
-      ext  <- liftE $ getBase uri
-      pure (mergeGhcupInfo base ext)
+      ext  <- liftE $ mapM (either pure getBase) exts
+      mergeGhcupInfo (base:ext)
 
-    where
-
-  mergeGhcupInfo :: GHCupInfo -- ^ base to merge with
-                 -> GHCupInfo -- ^ extension overwriting the base
-                 -> GHCupInfo
-  mergeGhcupInfo (GHCupInfo tr base base2) (GHCupInfo _ ext ext2) =
-    let newDownloads = M.mapWithKey (\k a -> case M.lookup k ext of
-                                        Just a' -> M.union a' a
-                                        Nothing -> a
-                                    ) base
-        newGlobalTools = M.union base2 ext2
-    in GHCupInfo tr newDownloads newGlobalTools
+ where
+  mergeGhcupInfo :: MonadFail m
+                 => [GHCupInfo]
+                 -> m GHCupInfo
+  mergeGhcupInfo [] = fail "mergeGhcupInfo: internal error: need at least one GHCupInfo"
+  mergeGhcupInfo xs@(GHCupInfo{}: _) =
+    let newDownloads   = M.unionsWith (M.unionWith (\_ b2 -> b2)) (_ghcupDownloads   <$> xs)
+        newGlobalTools = M.unionsWith (\_ a2 -> a2              ) (_globalTools      <$> xs)
+        newToolReqs    = M.unionsWith (M.unionWith (\_ b2 -> b2)) (_toolRequirements <$> xs)
+    in pure $ GHCupInfo newToolReqs newDownloads newGlobalTools
 
 
 yamlFromCache :: (MonadReader env m, HasDirs env) => URI -> m FilePath

lib/GHCup/Types.hs

@@ -286,9 +286,9 @@ instance Pretty TarDir where
 
 -- | Where to fetch GHCupDownloads from.
 data URLSource = GHCupURL
-               | OwnSource URI
+               | OwnSource [Either GHCupInfo URI] -- ^ complete source list
                | OwnSpec GHCupInfo
-               | AddSource (Either GHCupInfo URI) -- ^ merge with GHCupURL
+               | AddSource [Either GHCupInfo URI] -- ^ merge with GHCupURL
                deriving (GHC.Generic, Show)
 
 instance NFData URLSource

lib/GHCup/Types/JSON.hs

@@ -79,6 +79,38 @@ instance FromJSON Tag where
 instance ToJSON URI where
   toJSON = toJSON . E.decodeUtf8With E.lenientDecode . serializeURIRef'
 
+instance FromJSON URLSource where
+  parseJSON v =
+        parseGHCupURL v
+    <|> parseOwnSourceLegacy v
+    <|> parseOwnSourceNew1 v
+    <|> parseOwnSourceNew2 v
+    <|> parseOwnSpec v
+    <|> legacyParseAddSource v
+    <|> newParseAddSource v
+   where
+    parseOwnSourceLegacy = withObject "URLSource" $ \o -> do
+      r :: URI <- o .: "OwnSource"
+      pure (OwnSource [Right r])
+    parseOwnSourceNew1 = withObject "URLSource" $ \o -> do
+      r :: [URI] <- o .: "OwnSource"
+      pure (OwnSource (fmap Right r))
+    parseOwnSourceNew2 = withObject "URLSource" $ \o -> do
+      r :: [Either GHCupInfo URI] <- o .: "OwnSource"
+      pure (OwnSource r)
+    parseOwnSpec = withObject "URLSource" $ \o -> do
+      r :: GHCupInfo <- o .: "OwnSpec"
+      pure (OwnSpec r)
+    parseGHCupURL = withObject "URLSource" $ \o -> do
+      _ :: [Value] <- o .: "GHCupURL"
+      pure GHCupURL
+    legacyParseAddSource = withObject "URLSource" $ \o -> do
+      r :: Either GHCupInfo URI <- o .: "AddSource"
+      pure (AddSource [r])
+    newParseAddSource = withObject "URLSource" $ \o -> do
+      r :: [Either GHCupInfo URI] <- o .: "AddSource"
+      pure (AddSource r)
+
 instance FromJSON URI where
   parseJSON = withText "URL" $ \t ->
     case parseURI strictURIParserOptions (encodeUtf8 t) of
@@ -314,7 +346,7 @@ deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''Requir
 deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''DownloadInfo
 deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''VersionInfo
 deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''GHCupInfo
-deriveJSON defaultOptions { sumEncoding = ObjectWithSingleField } ''URLSource
+deriveToJSON defaultOptions { sumEncoding = ObjectWithSingleField } ''URLSource
 deriveJSON defaultOptions { sumEncoding = ObjectWithSingleField } ''Key
 deriveJSON defaultOptions { fieldLabelModifier = \str' -> maybe str' T.unpack . T.stripPrefix (T.pack "k-") . T.pack . kebab $ str' } ''UserKeyBindings
 deriveJSON defaultOptions { fieldLabelModifier = \str' -> maybe str' T.unpack . T.stripPrefix (T.pack "u-") . T.pack . kebab $ str' } ''UserSettings

lib/GHCup/Utils/Dirs.hs

@@ -339,13 +339,15 @@ useXDG = isJust <$> lookupEnv "GHCUP_USE_XDG_DIRS"
 relativeSymlink :: FilePath  -- ^ the path in which to create the symlink
                 -> FilePath  -- ^ the symlink destination
                 -> FilePath
-relativeSymlink p1 p2 =
-  let d1      = splitDirectories p1
-      d2      = splitDirectories p2
-      common  = takeWhile (\(x, y) -> x == y) $ zip d1 d2
-      cPrefix = drop (length common) d1
-  in  joinPath (replicate (length cPrefix) "..")
-        <> joinPath ([pathSeparator] : drop (length common) d2)
+relativeSymlink p1 p2
+  | isWindows = p2 -- windows quickly gets into MAX_PATH issues so we don't care about relative symlinks
+  | otherwise =
+    let d1      = splitDirectories p1
+        d2      = splitDirectories p2
+        common  = takeWhile (\(x, y) -> x == y) $ zip d1 d2
+        cPrefix = drop (length common) d1
+    in  joinPath (replicate (length cPrefix) "..")
+          <> joinPath ([pathSeparator] : drop (length common) d2)
 
 
 cleanupTrash :: ( MonadIO m

lib/GHCup/Utils/Prelude.hs

@@ -473,7 +473,7 @@ recyclePathForcibly fp
       liftIO (moveFile fp dest)
           `catch`
           (\e -> if | isDoesNotExistError e -> pure ()
-                    | isPermissionError e {- EXDEV on windows -} -> recover (liftIO $ removePathForcibly fp)
+                    | isPermissionError e || ioeGetErrorType e == UnsupportedOperation {- EXDEV on windows -} -> recover (liftIO $ removePathForcibly fp)
                     | otherwise -> throwIO e)
           `finally`
             liftIO (handleIO (\_ -> pure ()) $ removePathForcibly tmp)
@@ -515,7 +515,7 @@ recycleFile fp
       let dest = tmp </> takeFileName fp
       liftIO (moveFile fp dest)
         `catch`
-          (\e -> if isPermissionError e {- EXDEV on windows -} then recover (liftIO $ removePathForcibly fp) else throwIO e)
+          (\e -> if isPermissionError e || ioeGetErrorType e == UnsupportedOperation {- EXDEV on windows -} then recover (liftIO $ removePathForcibly fp) else throwIO e)
         `finally`
           liftIO (handleIO (\_ -> pure ()) $ removePathForcibly tmp)
   | otherwise = liftIO $ removeFile fp

mkdocs.yml

@@ -13,7 +13,8 @@ theme:
 
 nav:
   - Home: index.md
-  - "Getting Started": install.md
+  - "Getting started": install.md
+  - "First steps": steps.md
   - "User Guide": guide.md
   - "Developer Guide": dev.md
   - About: about.md

scripts/bootstrap/bootstrap-haskell

@@ -25,7 +25,7 @@
 
 plat="$(uname -s)"
 arch=$(uname -m)
-ghver="0.1.17.5"
+ghver="0.1.17.6"
 base_url="https://downloads.haskell.org/~ghcup"
 
 export GHCUP_SKIP_UPDATE_CHECK=yes
@@ -157,7 +157,7 @@ _done() {
 				green "and the \"Mingw package management docs\""
 				green "desktop shortcuts."
 				green
-				green "If you are new to Haskell, check out https://www.haskell.org/ghcup/install/#first-steps"
+				green "If you are new to Haskell, check out https://www.haskell.org/ghcup/steps/"
 				;;
 			*)
 				green
@@ -172,7 +172,7 @@ _done() {
 				green "To install other GHC versions and tools, run:"
 				green "  ghcup tui"
 				green
-				green "If you are new to Haskell, check out https://www.haskell.org/ghcup/install/#first-steps"
+				green "If you are new to Haskell, check out https://www.haskell.org/ghcup/steps/"
 				;;
 
 	esac
@@ -181,6 +181,51 @@ _done() {
 	exit 0
 }
 
+# @FUNCTION: posix_realpath
+# @USAGE: <file>
+# @DESCRIPTION:
+# Portably gets the realpath and prints it to stdout.
+# This was initially inspired by
+#   https://gist.github.com/tvlooy/cbfbdb111a4ebad8b93e
+#   and
+#   https://stackoverflow.com/a/246128
+#
+# If the file does not exist, just prints it appended to the current directory.
+# @STDOUT: realpath of the given file
+posix_realpath() {
+    [ -z "$1" ] && die "Internal error: no argument given to posix_realpath"
+    current_loop=0
+    max_loops=50
+    mysource=$1
+    # readlink and '[ -h $path ]' behave different wrt '/sbin/' and '/sbin', so we strip it
+    mysource=${mysource%/}
+    [ -z "${mysource}" ] && mysource=$1
+
+    while [ -h "${mysource}" ]; do
+        current_loop=$((current_loop+1))
+        mydir="$( cd -P "$( dirname "${mysource}" )" > /dev/null 2>&1 && pwd )"
+        mysource="$(readlink "${mysource}")"
+        [ "${mysource%"${mysource#?}"}"x != '/x' ] && mysource="${mydir%/}/${mysource}"
+
+        if [ ${current_loop} -gt ${max_loops} ] ; then
+            (>&2 echo "${1}: Too many levels of symbolic links")
+			echo "$1"
+            return
+        fi
+    done
+    mydir="$( cd -P "$( dirname "${mysource}" )" > /dev/null 2>&1 && pwd )"
+
+    # TODO: better distinguish between "does not exist" and "permission denied"
+    if [ -z "${mydir}" ] ; then
+        (>&2 echo "${1}: Permission denied")
+		echo "$(pwd)/$1"
+    else
+        echo "${mydir%/}/$(basename "${mysource}")"
+    fi
+
+    unset current_loop max_loops mysource mydir
+}
+
 download_ghcup() {
 
     case "${plat}" in
@@ -427,23 +472,23 @@ adjust_bashrc() {
 					;;
 				fish)
 					mkdir -p "${GHCUP_PROFILE_FILE%/*}"
-					sed -i -e '/# ghcup-env$/ s/^#*/#/' "${GHCUP_PROFILE_FILE}"
+					sed -i -e '/# ghcup-env$/ s/^#*/#/' "$(posix_realpath "${GHCUP_PROFILE_FILE}")"
 					case $1 in
 						1)
-							echo "set -q GHCUP_INSTALL_BASE_PREFIX[1]; or set GHCUP_INSTALL_BASE_PREFIX \$HOME ; set -gx PATH \$HOME/.cabal/bin $GHCUP_BIN \$PATH # ghcup-env" >> "${GHCUP_PROFILE_FILE}"
+							printf "\n%s" "set -q GHCUP_INSTALL_BASE_PREFIX[1]; or set GHCUP_INSTALL_BASE_PREFIX \$HOME ; set -gx PATH \$HOME/.cabal/bin $GHCUP_BIN \$PATH # ghcup-env" >> "${GHCUP_PROFILE_FILE}"
 							;;
 						2)
-							echo "set -q GHCUP_INSTALL_BASE_PREFIX[1]; or set GHCUP_INSTALL_BASE_PREFIX \$HOME ; set -gx PATH \$HOME/.cabal/bin \$PATH $GHCUP_BIN # ghcup-env" >> "${GHCUP_PROFILE_FILE}"
+							printf "\n%s" "set -q GHCUP_INSTALL_BASE_PREFIX[1]; or set GHCUP_INSTALL_BASE_PREFIX \$HOME ; set -gx PATH \$HOME/.cabal/bin \$PATH $GHCUP_BIN # ghcup-env" >> "${GHCUP_PROFILE_FILE}"
 							;;
 					esac
 					;;
 				bash)
-					sed -i -e '/# ghcup-env$/ s/^#*/#/' "${GHCUP_PROFILE_FILE}"
-					echo "[ -f \"${GHCUP_DIR}/env\" ] && source \"${GHCUP_DIR}/env\" # ghcup-env" >> "${GHCUP_PROFILE_FILE}"
+					sed -i -e '/# ghcup-env$/ s/^#*/#/' "$(posix_realpath "${GHCUP_PROFILE_FILE}")"
+					printf "\n%s" "[ -f \"${GHCUP_DIR}/env\" ] && source \"${GHCUP_DIR}/env\" # ghcup-env" >> "${GHCUP_PROFILE_FILE}"
 					case "${plat}" in
 						"Darwin"|"darwin")
 							if ! grep -q "ghcup-env" "${HOME}/.bash_profile" ; then
-								echo "[[ -f ~/.bashrc ]] && source ~/.bashrc # ghcup-env" >> "${HOME}/.bash_profile"
+								printf "\n%s" "[[ -f ~/.bashrc ]] && source ~/.bashrc # ghcup-env" >> "${HOME}/.bash_profile"
 							fi
 							;;
 						MSYS*|MINGW*)
@@ -457,8 +502,8 @@ adjust_bashrc() {
 					;;
 
 				zsh)
-					sed -i -e '/# ghcup-env$/ s/^#*/#/' "${GHCUP_PROFILE_FILE}"
-					echo "[ -f \"${GHCUP_DIR}/env\" ] && source \"${GHCUP_DIR}/env\" # ghcup-env" >> "${GHCUP_PROFILE_FILE}"
+					sed -i -e '/# ghcup-env$/ s/^#*/#/' "$(posix_realpath "${GHCUP_PROFILE_FILE}")"
+					printf "\n%s" "[ -f \"${GHCUP_DIR}/env\" ] && source \"${GHCUP_DIR}/env\" # ghcup-env" >> "${GHCUP_PROFILE_FILE}"
 					;;
 			esac
 			echo