briefer, more informative usage error messages

hledger-chart/Hledger/Chart/Main.hs

@@ -59,7 +59,7 @@ usage_chart = concat [
 
 main :: IO ()
 main = do
-  (opts, args) <- parseArgumentsWith (options_cli++options_chart) usage_chart
+  (opts, args) <- parseArgumentsWith $ options_cli++options_chart
   run opts args
     where
       run opts args

hledger-vty/Hledger/Vty/Main.hs

@@ -49,7 +49,7 @@ usage_vty = concat [
 
 main :: IO ()
 main = do
-  (opts, args) <- parseArgumentsWith (options_cli++options_vty) usage_vty
+  (opts, args) <- parseArgumentsWith $ options_cli++options_vty
   run opts args
     where
       run opts args

hledger-web/Hledger/Web/Main.hs

@@ -54,7 +54,7 @@ usage_web = concat [
 
 main :: IO ()
 main = do
-  (opts, args) <- parseArgumentsWith (options_cli++options_web) usage_web
+  (opts, args) <- parseArgumentsWith $ options_cli++options_web
   run opts args
     where
       run opts args

hledger/Hledger/Cli/Main.hs

@@ -54,14 +54,15 @@ import Hledger.Cli.Version (progversionstr, binaryfilename)
 
 main :: IO ()
 main = do
-  (opts, args) <- parseArgumentsWith options_cli usage_cli
+  (opts, args) <- parseArgumentsWith options_cli
   run opts args
     where
-      run _ []                        = putStr usage_cli
-      run opts (cmd:args)
+      run opts _
        | Help `elem` opts             = putStr usage_cli
        | Version `elem` opts          = putStrLn $ progversionstr progname_cli
        | BinaryFilename `elem` opts   = putStrLn $ binaryfilename progname_cli
+      run _ []                        = argsError "a command is required."
+      run opts (cmd:args)
        | cmd `isPrefixOf` "balance"   = withJournalDo opts args cmd balance
        | cmd `isPrefixOf` "convert"   = withJournalDo opts args cmd convert
        | cmd `isPrefixOf` "print"     = withJournalDo opts args cmd print'
@@ -70,4 +71,4 @@ main = do
        | cmd `isPrefixOf` "add"       = withJournalDo opts args cmd add
        | cmd `isPrefixOf` "stats"     = withJournalDo opts args cmd stats
        | cmd `isPrefixOf` "test"      = runtests opts args >> return ()
-       | otherwise                    = putStr usage_cli
+       | otherwise                    = argsError $ "command "++cmd++" is unrecognized."

hledger/Hledger/Cli/Options.hs

@@ -146,15 +146,18 @@ optValuesForConstructors fs opts = concatMap get opts
 -- converted to explicit YYYY/MM/DD format based on the current time. If
 -- parsing fails, raise an error, displaying the problem along with the
 -- provided usage string.
-parseArgumentsWith :: [OptDescr Opt] -> String -> IO ([Opt], [String])
-parseArgumentsWith options usage = do
-  rawargs <- liftM (map decodeString) getArgs
+parseArgumentsWith :: [OptDescr Opt] -> IO ([Opt], [String])
+parseArgumentsWith options = do
+  rawargs <- map decodeString `fmap` getArgs
   let (opts,args,errs) = getOpt Permute options rawargs
   opts' <- fixOptDates opts
   let opts'' = if Debug `elem` opts' then Verbose:opts' else opts'
   if null errs
    then return (opts'',args)
-   else ioError $ userError' $ concat errs ++ usage
+   else argsError (concat errs) >> return ([],[])
+
+argsError :: String -> IO ()
+argsError = ioError . userError' . (++ " Run with --help to see usage.")
 
 -- | Convert any fuzzy dates within these option values to explicit ones,
 -- based on today's date.