Tests for foldable

src/Data/Functor/Foldable.hs

@@ -17,8 +17,16 @@ module Data.Functor.Foldable
   )
   where
 
+import Data.Functor.Classes
+
 newtype Fix f = Fix { getFix :: f (Fix f) }
 
+instance Show1 f => Show (Fix f) where
+  showsPrec d (Fix f) = showString "Fix " . showsPrec1 d f
+
+instance Eq1 f => Eq (Fix f) where
+  (Fix a) == (Fix b) = liftEq (==) a b
+
 -- | Catamorphism or the fold
 --
 -- Fold a recursive structure into a value