Generalise hoistCofree

ekmett · Apr 5, 2016 · 1ad07d5 · 1ad07d5
1 parent ad1080d
commit 1ad07d5
Showing 1 changed file with 1 addition and 2 deletions.
diff --git a/src/Control/Comonad/Cofree.hs b/src/Control/Comonad/Cofree.hs
@@ -1,5 +1,4 @@
 {-# LANGUAGE CPP #-}
-{-# LANGUAGE Rank2Types #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE UndecidableInstances #-}
@@ -125,7 +124,7 @@ unfold f c = case f c of
 unfoldM :: (Traversable f, Monad m) => (b -> m (a, f b)) -> b -> m (Cofree f a)
 unfoldM f = f >=> \ (x, t) -> (x :<) `liftM` Data.Traversable.mapM (unfoldM f) t
 
-hoistCofree :: Functor f => (forall x . f x -> g x) -> Cofree f a -> Cofree g a
+hoistCofree :: Functor f => (f (Cofree g a) -> g (Cofree g a)) -> Cofree f a -> Cofree g a
 hoistCofree f (x :< y) = x :< f (hoistCofree f <$> y)
 
 instance Functor f => ComonadCofree f (Cofree f) where