From a80ee2cdb409a34046c03de1c82248e9f45429c2 Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@me.com>
Date: Sat, 9 Sep 2017 19:03:15 +0100
Subject: [PATCH] Derive hella instances for Env.

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

diff --git a/src/Diff.hs b/src/Diff.hs
index e5e233caa..6a536bfcb 100644
--- a/src/Diff.hs
+++ b/src/Diff.hs
@@ -29,7 +29,7 @@ newtype MetaVar = MetaVar { unMetaVar :: String }
   deriving (Eq, Ord, Show)
 
 newtype Env a = Env { unEnv :: [(MetaVar, a)] }
-  deriving (Eq, Monoid, Ord, Show)
+  deriving (Eq, Foldable, Functor, Monoid, Ord, Show, Traversable)
 
 envExtend :: MetaVar -> a -> Env a -> Env a
 envExtend var val (Env m) = Env ((var, val) : m)