Generalize show for matrix

Matrix.hs

@@ -1,4 +1,5 @@
 module Matrix where
+import Data.List  (intercalate)
 
 data Mat a = Mat [[a]]
 type Pos  = (Int, Int)
@@ -6,6 +7,9 @@ type Pos  = (Int, Int)
 instance Functor Mat where
   fmap f (Mat m) = Mat ((map . map) f m)
 
+instance (Show a) => Show (Mat a) where
+  show (Mat m) = concatMap ((++"\n") . intercalate " " . map show) m
+
 -- | Safely access a list
 -- [4,1,5,9] ?? 2 == Just 5
 -- [5,7] ?? 3 == Nothing

life.hs

@@ -1,16 +1,8 @@
-{-#LANGUAGE TypeSynonymInstances, FlexibleInstances#-}
-import Data.Maybe (listToMaybe)
-import Data.List  (intercalate)
 import Matrix
 
 type Cell = Int
 type Grid = Mat Cell
 
-instance Show Grid where
-  show (Mat m) = concatMap ((++"\n") . intercalate " " . map replace) m
-    where
-      replace 1 = "■"
-      replace 0 = "'"
 
 -- | Get the state of a cell
 -- 0 when out of the grid