1 files changed, 3 insertions, 4 deletions
diff --git a/compiler/rename/RnPat.hs b/compiler/rename/RnPat.hs
index ca8c665e28..4a08ab4761 100644
--- a/compiler/rename/RnPat.hs
+++ b/compiler/rename/RnPat.hs
@@ -16,6 +16,7 @@ free variables.
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE ViewPatterns #-}
+{-# LANGUAGE DeriveFunctor #-}
 
 module RnPat (-- main entry points
               rnPat, rnPats, rnBindPat, rnPatAndThen,
@@ -72,7 +73,7 @@ import TysWiredIn          ( nilDataCon )
 import DataCon
 import qualified GHC.LanguageExtensions as LangExt
 
-import Control.Monad       ( when, liftM, ap, guard )
+import Control.Monad       ( when, ap, guard )
 import qualified Data.List.NonEmpty as NE
 import Data.Ratio
 
@@ -107,11 +108,9 @@ p1 scope over p2,p3.
 
 newtype CpsRn b = CpsRn { unCpsRn :: forall r. (b -> RnM (r, FreeVars))
                                             -> RnM (r, FreeVars) }
+        deriving (Functor)
         -- See Note [CpsRn monad]
 
-instance Functor CpsRn where
-    fmap = liftM
-
 instance Applicative CpsRn where
     pure x = CpsRn (\k -> k x)
     (<*>) = ap