improve --help display for commands

CmdLine.hs

@@ -75,13 +75,10 @@ dispatch fuzzyok allargs allcmds commonoptions fields header getgitrepo = do
 parseCmd :: CmdParams -> [Command] -> (Command -> O.Parser v) -> O.ParserResult (Command, v)
 parseCmd allargs allcmds getparser = O.execParserPure (O.prefs O.idm) pinfo allargs
   where
-	pinfo = O.info (O.subparser $ mconcat $ map mkcommand allcmds)
-		( O.fullDesc
-		<> O.progDesc "hiya"
-		<> O.header "ook - aaa"
-		)
+	pinfo = O.info (O.helper <*> subcmds) O.fullDesc
+	subcmds = O.subparser $ mconcat $ map mkcommand allcmds
 	mkcommand c = O.command (cmdname c) $ O.info (mkparser c) 
-		(O.fullDesc <> O.progDesc (cmddesc c))
+		(O.fullDesc <> O.header (cmddesc c))
 	mkparser c = (,)
 		<$> pure c
 		<*> getparser c

CmdLine/Usage.hs

@@ -10,8 +10,6 @@ module CmdLine.Usage where
 import Common.Annex
 import Types.Command
 
-import System.Console.GetOpt
-
 usageMessage :: String -> String
 usageMessage s = "Usage: " ++ s
 
@@ -41,20 +39,6 @@ usage header cmds = unlines $ usageMessage header : concatMap go [minBound..]
 	longest f = foldl max 0 $ map (length . f) cmds
 	scmds = sort cmds
 
-{- Usage message for a single command. -}
-commandUsage :: Command -> String
-commandUsage cmd = unlines
-	[ usageInfo header (cmdoptions cmd)
-	, "To see additional options common to all commands, run: git annex help options"
-	]
-  where
-	header = usageMessage $ unwords
-		[ "git-annex"
-		, cmdname cmd
-		, cmdparamdesc cmd
-		, "[option ...]"
-		]
-
 {- Descriptions of params used in usage messages. -}
 paramPaths :: String
 paramPaths = paramRepeating paramPath -- most often used