Making combinaison work & adding default values

GetOpt.hs

@@ -23,7 +23,9 @@ getOpt p args = case runParser p args of
 
 runParser :: Parser a -> [String] -> Maybe (Parser a, [String])
 runParser p@(DefParser _) args = Nothing
-runParser (OptParser _ _) [] = Nothing
+runParser (OptParser opt next) [] = do
+    def <- defaultValue opt
+    return (fmap def next, [])
 runParser (OptParser _ _) [_] = Nothing -- TODO remove this and support default values
 runParser (OptParser opt next) (identifier:arg:args)
     | optionMatch opt identifier = do

GetOpt/Parsers.hs

@@ -17,6 +17,7 @@ instance Applicative Parser where
     pure a = DefParser a
 
     -- (<*>) f (a -> b) -> f a -> f b
-    (<*>) (DefParser f) p = fmap f p
+    (<*>) (DefParser f) p = f <$> p
     -- (<*>) (OptParser (Option (a -> b -> c)) Parser (a -> b)) -> Parser a -> Parser c
-    (<*>) (OptParser f next) p = OptParser () next
+    -- Ret: OptParser (Option ((a, b) -> c)) (Parser (a, b)) :: Parser (a, b)
+    (<*>) (OptParser f next) p = OptParser (uncurry <$> f) (fmap (,) next <*> p)

Main.hs

@@ -24,14 +24,35 @@ getParser = Configuration
             <> help "At witch line should we start"
             <> value 0
          )
+         <*> option (Just . auto) (
+               long "lines"
+            <> short 'l'
+            <> meta "LINES"
+            <> help "The number of lines to print"
+            <> value Nothing
+         )
+         <*> option auto (
+               long "window"
+            <> short 'w'
+            <> meta "WINDOW"
+            <> help "The size of the window (how long a line should be)"
+            <> value 80
+         )
+         <*> option auto (
+               long "move"
+            <> short 'm'
+            <> meta "MOVE"
+            <> help "Offset every lines."
+            <> value 0
+         )
 
 
 
 data Configuration = Configuration {
     rule :: Int,
-    start :: Int
-    -- lines :: Maybe Int,
-    -- window :: Int,
-    -- move :: Int
+    start :: Int,
+    lines :: Maybe Int,
+    window :: Int,
+    move :: Int
 } deriving Show