| Prefix (String -> m ()) -- -farg
| OptPrefix (String -> m ()) -- -f or -farg (i.e. the arg is optional)
| OptIntSuffix (Maybe Int -> m ()) -- -f or -f=n; pass n to fn
+ | IntSuffix (Int -> m ()) -- -f or -f=n; pass n to fn
| PassFlag (String -> m ()) -- -f; pass "-f" fn
| AnySuffix (String -> m ()) -- -f or -farg; pass entire "-farg" to fn
| PrefixPred (String -> Bool) (String -> m ())
| AnySuffixPred (String -> Bool) (String -> m ())
-
+
processArgs :: Monad m
=> [(String, OptKind m)] -- cmdline parser spec
-> [String] -- args
PassFlag f | notNull rest -> unknownFlagErr dash_arg
| otherwise -> Right (f dash_arg, args)
- OptIntSuffix f | Just n <- parseInt rest -> Right (f n, args)
+ OptIntSuffix f | null rest -> Right (f Nothing, args)
+ | Just n <- parseInt rest -> Right (f (Just n), args)
| otherwise -> Left ("malformed integer argument in " ++ dash_arg)
+ IntSuffix f | Just n <- parseInt rest -> Right (f n, args)
+ | otherwise -> Left ("malformed integer argument in " ++ dash_arg)
+
OptPrefix f -> Right (f rest, args)
AnySuffix f -> Right (f dash_arg, args)
AnySuffixPred p f -> Right (f dash_arg, args)
-
findArg :: [(String,OptKind a)] -> String -> Maybe (String,OptKind a)
findArg spec arg
= case [ (removeSpaces rest, k)
arg_ok (Prefix _) rest arg = notNull rest
arg_ok (PrefixPred p _) rest arg = notNull rest && p rest
arg_ok (OptIntSuffix _) rest arg = True
+arg_ok (IntSuffix _) rest arg = True
arg_ok (OptPrefix _) rest arg = True
arg_ok (PassFlag _) rest arg = null rest
arg_ok (AnySuffix _) rest arg = True
arg_ok (AnySuffixPred p _) rest arg = p arg
-parseInt :: String -> Maybe (Maybe Int)
+parseInt :: String -> Maybe Int
-- Looks for "433" or "=342", with no trailing gubbins
--- empty string => Just Nothing
--- n or =n => Just (Just n)
+-- n or =n => Just n
-- gibberish => Nothing
-parseInt s
- | null s = Just Nothing
- | otherwise = case reads (dropEq s) of
- ((n,""):_) -> Just (Just n)
- other -> Nothing
+parseInt s = case reads (dropEq s) of
+ ((n,""):_) -> Just n
+ other -> Nothing
dropEq :: String -> String
-- Discards a leading equals sign