diff --git a/day2.hs b/day2.hs index c67cff2..f95aa7a 100644 --- a/day2.hs +++ b/day2.hs @@ -32,13 +32,13 @@ validB (Password a' b' t p) = b = (pred b') parse :: String -> Maybe Password -parse [] = error "empty password" +parse [] = Nothing parse s = do (l,s') <- parseInt s (u,s'') <- parseInt $ dropChar s' (t,s''') <- parseChar $ dropChar s'' let p = (dropChar . dropChar) s''' - in (Just $ Password l u t p) + in Just $ Password l u t p parseInt :: String -> Maybe (Int,String) parseInt s = case (reads s) of