add help command

Command/Help.hs

@@ -0,0 +1,51 @@
+{- git-annex command
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Command.Help where
+
+import Common.Annex
+import Command
+import qualified Command.Init
+import qualified Command.Add
+import qualified Command.Drop
+import qualified Command.Get
+import qualified Command.Move
+import qualified Command.Copy
+import qualified Command.Sync
+import qualified Command.Whereis
+import qualified Command.Fsck
+
+def :: [Command]
+def = [noCommit $ noRepo showHelp $ dontCheck repoExists $
+	command "help" paramNothing seek "display help"]
+
+seek :: [CommandSeek]
+seek = [withWords start]
+
+start :: [String] -> CommandStart
+start _ = do
+	liftIO showHelp
+	stop
+
+showHelp :: IO ()
+showHelp = liftIO $ putStrLn $ unlines
+	[ "The most commonly used git-annex commands are:"
+	, unlines $ map cmdline $ concat
+		[ Command.Init.def
+		, Command.Add.def
+		, Command.Drop.def
+		, Command.Get.def
+		, Command.Move.def
+		, Command.Copy.def
+		, Command.Sync.def
+		, Command.Whereis.def
+		, Command.Fsck.def
+		]
+	, "Run git-annex without any options for a complete command and option list."
+	]
+	where
+		cmdline c = "\t" ++ cmdname c ++ "\t" ++ cmddesc c