Convert cost of costs and cards

Magic.hs

@@ -18,13 +18,13 @@ data Mana = Mana Int Color
 data Cost = Cost [Mana]
     deriving (Show, Eq)
 
-converted :: Cost -> Int
+class ManaCost a where
+    converted :: a -> Int
+
+instance ManaCost Cost where
     converted (Cost []) = 0
     converted (Cost cost) = (foldl (\t (Mana x _) -> t + x) 0) cost
 
-converted_card :: Card -> Int
-converted_card (Card _ _ cost) = converted cost
-
 color :: Color -> Cost -> Int
 color c (Cost cost) = converted (Cost (filter (\(Mana _ col) -> col == c) cost))
 
@@ -52,5 +52,8 @@ data Rarity = Land
 data Card = Card Rarity String Cost
     deriving (Show, Eq)
 
+instance ManaCost Card where
+    converted (Card _ _ cost) = converted cost
+
 deck = (replicate 13 (Card Land "Swamp" (Cost []))) ++ (replicate 13 (Card Land "Plains" (Cost [])))
     ++ replicate 4 (Card Mythic "Jace Beleren" (Cost [Mana 1 Colorless, Mana 2 Blue]))