describe subcommands

yesod/main.hs

@@ -11,6 +11,9 @@ import Types
 
 import Build (touch)
 import Devel (devel)
+import System.IO (stdout, stderr, hPutStr, hPutStrLn)
+import System.Exit (exitSuccess, exitFailure)
+import Control.Monad.IO.Class (MonadIO, liftIO)
 
 defineOptions "NoOptions" (return ())
 
@@ -31,7 +34,7 @@ cabalCommand mopt
   | optCabalDev mopt = "cabal-dev"
   | otherwise        = "cabal"
 
-main = runSubcommand
+main = runSubcommand'
       [ subcommand "init"      cmdInit
       , subcommand "configure" cmdConfigure
 #ifndef WINDOWS
@@ -64,5 +67,33 @@ cmdDevel mopt opts args = devel (optCabalDev mopt) args
 cmdVersion :: MainOptions -> VersionOptions -> [String] -> IO ()
 cmdVersion _ _ _ = putStrLn $ "yesod-core version: " ++ yesodVersion
 
+-- temporary hack to describe subcommands, remove once options supports subcommand descriptions
+runSubcommand' :: (Options opts, MonadIO m) => [Subcommand opts (m a)] -> m a
+runSubcommand' subcommands = do
+  argv <- liftIO System.Environment.getArgs
+  let parsed = parseSubcommand subcommands argv
+  case parsedSubcommand parsed of
+    Just cmd -> cmd
+    Nothing -> liftIO $ case parsedError parsed of
+                          Just err -> do
+                                 hPutStrLn stderr (parsedHelp parsed)
+                                 hPutStrLn stderr describeSubcommands
+                                 hPutStrLn stderr err
+                                 exitFailure
+                          Nothing -> do
+                                 hPutStr stdout (parsedHelp parsed)
+                                 hPutStr stdout describeSubcommands
+                                 exitSuccess
 
-
+describeSubcommands :: String
+describeSubcommands = unlines
+  [ "Available subcommands, use `yesod --help subcommand' to get more information"
+  , "  init         Scaffold a new site"
+  , "  configure    Configure a project for building"
+#ifndef WINDOWS
+  , "  build        Build project (performs TH dependency analysis)"
+  , "  touch        Touch any files with altered TH dependencies but do not build"
+#endif
+  , "  devel        Run project with the devel server"
+  , "  version      Print the version of Yesod"
+  ]