From f45796ab4a8170648074d636ab02ee742d7acbba Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@github.com>
Date: Fri, 18 Mar 2016 12:59:49 -0400
Subject: [PATCH] Use the obvious type variable.

---
 src/Term.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Term.hs b/src/Term.hs
index d76c382b9..0abbff04c 100644
--- a/src/Term.hs
+++ b/src/Term.hs
@@ -24,7 +24,7 @@ zipTerms (annotation1 :< a) (annotation2 :< b) = annotate $ zipUnwrap a b
     zipUnwrapMaps a' b' key = (,) key <$> zipTerms (a' ! key) (b' ! key)
 
 -- | Fold a term into some other value, starting with the leaves.
-cata :: Functor f => (annotation -> f b -> b) -> Cofree f annotation -> b
+cata :: Functor f => (annotation -> f a -> a) -> Cofree f annotation -> a
 cata f = uncurry f . second (fmap (cata f)) . unCofree
 
 -- | Unfold a term and its annotation starting from a seed value.