Style

Main.hs

@@ -5,6 +5,4 @@ import System.Environment
 main :: IO ()
 main = do
   a <- getArgs
-  case null a of
+  makeGUI (if null a then head a else "")
-    False -> makeGUI (head a)
-    True  -> makeGUI ""

Parser.hs

@@ -17,7 +17,7 @@ newtype Parser a = MkParser { runParser :: String -> Maybe (a, String) }
 
 -- |Functor instance.
 instance Functor Parser where
-  fmap f p = (inParser . fmap . fmap . first $ f) p
+  fmap = inParser . fmap . fmap . first
 
 -- |Applicative functor instance.
 instance Applicative Parser where