Just use the cache for commands which refer to locally stored objects.

Setting a version of GHC will fail if provided with a version not installed,
and we don't neede to check the most recent list of GHCs available to know
that.

app/ghcup/Main.hs

@@ -495,7 +495,7 @@ installOpts tool =
                     )
                   )
                 )
-            <*> (Just <$> toolVersionArgument Nothing tool)
+            <*> (Just <$> toolVersionArgument True Nothing tool)
             )
         <|> (pure (Nothing, Nothing))
         )
@@ -560,7 +560,7 @@ setParser =
 
 
 setOpts :: Maybe Tool -> Parser SetOptions
-setOpts tool = SetOptions <$> optional (toolVersionArgument (Just ListInstalled) tool)
+setOpts tool = SetOptions <$> optional (toolVersionArgument False (Just ListInstalled) tool)
 
 listOpts :: Parser ListOptions
 listOpts =
@@ -614,7 +614,7 @@ rmParser =
 
 
 rmOpts :: Maybe Tool -> Parser RmOptions
-rmOpts tool = RmOptions <$> versionArgument (Just ListInstalled) tool
+rmOpts tool = RmOptions <$> versionArgument False (Just ListInstalled) tool
 
 
 changelogP :: Parser ChangeLogOptions
@@ -636,7 +636,7 @@ changelogP =
             )
           )
         )
-    <*> optional (toolVersionArgument Nothing Nothing)
+    <*> optional (toolVersionArgument True Nothing Nothing)
 
 compileP :: Parser CompileCommand
 compileP = subparser
@@ -765,13 +765,13 @@ toolVersionParser = verP' <|> toolP
           )
 
 -- | same as toolVersionParser, except as an argument.
-toolVersionArgument :: Maybe ListCriteria -> Maybe Tool -> Parser ToolVersion
+toolVersionArgument :: Bool -> Maybe ListCriteria -> Maybe Tool -> Parser ToolVersion
-toolVersionArgument criterial tool =
+toolVersionArgument networkSensitive criteria tool =
-  argument (eitherReader toolVersionEither) (metavar "VERSION|TAG" <> completer tagCompleter <> foldMap (completer . versionCompleter criterial) tool)
+  argument (eitherReader toolVersionEither) (metavar "VERSION|TAG" <> completer tagCompleter <> foldMap (completer . versionCompleter networkSensitive criteria) tool)
 
 
-versionArgument :: Maybe ListCriteria -> Maybe Tool -> Parser GHCTargetVersion
+versionArgument :: Bool -> Maybe ListCriteria -> Maybe Tool -> Parser GHCTargetVersion
-versionArgument criterial tool = argument (eitherReader tVersionEither) (metavar "VERSION" <> foldMap (completer . versionCompleter criterial) tool)
+versionArgument networkSensitive criteria tool = argument (eitherReader tVersionEither) (metavar "VERSION" <> foldMap (completer . versionCompleter networkSensitive criteria) tool)
 
 
 tagCompleter :: Completer
@@ -781,8 +781,8 @@ tagCompleter =
   ]
 
 
-versionCompleter :: Maybe ListCriteria -> Tool -> Completer
+versionCompleter :: Bool -> Maybe ListCriteria -> Tool -> Completer
-versionCompleter criteria tool =
+versionCompleter networkSensitive criteria tool =
   listIOCompleter $ do
     let
       loggerConfig =
@@ -811,8 +811,12 @@ versionCompleter criteria tool =
 
       mGhcUpInfo <-
         runEnv . runE $
-          getDownloadsF $
+          if networkSensitive then
-            urlSource simpleSettings
+            getDownloadsF GHCupURL
+          else
+            catchE
+              (\(FileDoesNotExistError _) -> getDownloadsF GHCupURL)
+              readFromCache
 
       forFold mGhcUpInfo $ \(GHCupInfo _ dls) -> do
         installedVersions <-
@@ -831,7 +835,7 @@ versionParser = option
 
 versionParser' :: Parser Version
 versionParser' = argument
-  (eitherReader (bimap show id . version . T.pack))
+  (eitherReader (first show . version . T.pack))
   (metavar "VERSION")
 
 
@@ -842,7 +846,7 @@ tagEither s' = case fmap toLower s' of
   ('b':'a':'s':'e':'-':ver') -> case pvp (T.pack ver') of
                                   Right x -> Right (Base x)
                                   Left  _ -> Left [i|Invalid PVP version for base #{ver'}|]
-  other         -> Left ([i|Unknown tag #{other}|])
+  other         -> Left [i|Unknown tag #{other}|]
 
 
 tVersionEither :: String -> Either String GHCTargetVersion

lib/GHCup/Download.hs

@@ -137,30 +137,8 @@ getDownloadsF urlSource = do
       bsExt <- reThrowAll DownloadFailed $ downloadBS uri
       ext <- lE' JSONDecodeError $ bimap show id $ Y.decodeEither' (L.toStrict bsExt)
       pure (mergeGhcupInfo base ext)
- where
-  readFromCache :: (MonadIO m, MonadCatch m, MonadLogger m, MonadReader AppState m)
-                => Excepts '[JSONError, FileDoesNotExistError] m GHCupInfo
-  readFromCache = do
-    AppState {dirs = Dirs {..}} <- lift ask
-    lift $ $(logWarn)
-      [i|Could not get download info, trying cached version (this may not be recent!)|]
-    let path = view pathL' ghcupURL
-    yaml_file <- (cacheDir </>) <$> urlBaseName path
-    bs        <-
-      handleIO' NoSuchThing
-                (\_ -> throwE $ FileDoesNotExistError (toFilePath yaml_file))
-      $ liftIO
-      $ readFile yaml_file
-    lE' JSONDecodeError $ bimap show id $ Y.decodeEither' (L.toStrict bs)
 
-  getBase :: (MonadFail m, MonadIO m, MonadCatch m, MonadLogger m, MonadReader AppState m)
+    where
-          => Excepts '[JSONError , FileDoesNotExistError] m GHCupInfo
-  getBase =
-    handleIO (\_ -> readFromCache)
-    $ catchE @_ @'[JSONError, FileDoesNotExistError]
-        (\(DownloadFailed _) -> readFromCache)
-    $ ((reThrowAll @_ @_ @'[JSONError, DownloadFailed] DownloadFailed $ smartDl ghcupURL)
-      >>= (liftE . lE' @_ @_ @'[JSONError] JSONDecodeError . bimap show id . Y.decodeEither' . L.toStrict))
 
   mergeGhcupInfo :: GHCupInfo -- ^ base to merge with
                  -> GHCupInfo -- ^ extension overwriting the base
@@ -172,6 +150,32 @@ getDownloadsF urlSource = do
                            ) base
     in GHCupInfo tr new
 
+
+readFromCache :: (MonadIO m, MonadCatch m, MonadLogger m, MonadReader AppState m)
+              => Excepts '[JSONError, FileDoesNotExistError] m GHCupInfo
+readFromCache = do
+  AppState {dirs = Dirs {..}} <- lift ask
+  lift $ $(logWarn)
+    [i|Could not get download info, trying cached version (this may not be recent!)|]
+  let path = view pathL' ghcupURL
+  yaml_file <- (cacheDir </>) <$> urlBaseName path
+  bs        <-
+    handleIO' NoSuchThing
+              (\_ -> throwE $ FileDoesNotExistError (toFilePath yaml_file))
+    $ liftIO
+    $ readFile yaml_file
+  lE' JSONDecodeError $ bimap show id $ Y.decodeEither' (L.toStrict bs)
+
+
+getBase :: (MonadFail m, MonadIO m, MonadCatch m, MonadLogger m, MonadReader AppState m)
+        => Excepts '[JSONError , FileDoesNotExistError] m GHCupInfo
+getBase =
+  handleIO (\_ -> readFromCache)
+  $ catchE @_ @'[JSONError, FileDoesNotExistError]
+      (\(DownloadFailed _) -> readFromCache)
+  $ ((reThrowAll @_ @_ @'[JSONError, DownloadFailed] DownloadFailed $ smartDl ghcupURL)
+    >>= (liftE . lE' @_ @_ @'[JSONError] JSONDecodeError . bimap show id . Y.decodeEither' . L.toStrict))
+    where
   -- First check if the json file is in the ~/.ghcup/cache dir
   -- and check it's access time. If it has been accessed within the
   -- last 5 minutes, just reuse it.
@@ -209,8 +213,8 @@ getDownloadsF urlSource = do
       then do
         accessTime <-
           PF.accessTimeHiRes
-            <$> (liftIO $ PF.getFileStatus (toFilePath json_file))
+            <$> liftIO (PF.getFileStatus (toFilePath json_file))
-        currentTime <- liftIO $ getPOSIXTime
+        currentTime <- liftIO getPOSIXTime
 
         -- access time won't work on most linuxes, but we can try regardless
         if (currentTime - accessTime) > 300