Use DeriveFunctor throughout the codebase (#15654)

2 files changed, 5 insertions, 7 deletions

diff --git a/compiler/codeGen/StgCmmExtCode.hs b/compiler/codeGen/StgCmmExtCode.hs
index 551535d758..1d35c3454e 100644
--- a/compiler/codeGen/StgCmmExtCode.hs
+++ b/compiler/codeGen/StgCmmExtCode.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE DeriveFunctor #-}
 -- | Our extended FCode monad.
 
 -- We add a mapping from names to CmmExpr, to support local variable names in
@@ -53,7 +54,7 @@ import UniqFM
 import Unique
 import UniqSupply
 
-import Control.Monad (liftM, ap)
+import Control.Monad (ap)
 
 -- | The environment contains variable definitions or blockids.
 data Named
@@ -73,6 +74,7 @@ type Decls      = [(FastString,Named)]
 --      and a list of local declarations. Returns the resulting list of declarations.
 newtype CmmParse a
         = EC { unEC :: String -> Env -> Decls -> FCode (Decls, a) }
+    deriving (Functor)
 
 type ExtCode = CmmParse ()
 
@@ -82,9 +84,6 @@ returnExtFC a   = EC $ \_ _ s -> return (s, a)
 thenExtFC :: CmmParse a -> (a -> CmmParse b) -> CmmParse b
 thenExtFC (EC m) k = EC $ \c e s -> do (s',r) <- m c e s; unEC (k r) c e s'
 
-instance Functor CmmParse where
-      fmap = liftM
-
 instance Applicative CmmParse where
       pure = returnExtFC
       (<*>) = ap
diff --git a/compiler/codeGen/StgCmmMonad.hs b/compiler/codeGen/StgCmmMonad.hs
index 8be5c4551f..d6f84c6a0a 100644
--- a/compiler/codeGen/StgCmmMonad.hs
+++ b/compiler/codeGen/StgCmmMonad.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE GADTs #-}
 
 -----------------------------------------------------------------------------
@@ -111,9 +112,7 @@ import Data.List
 --------------------------------------------------------
 
 newtype FCode a = FCode { doFCode :: CgInfoDownwards -> CgState -> (a, CgState) }
-
-instance Functor FCode where
-    fmap f (FCode g) = FCode $ \i s -> case g i s of (a, s') -> (f a, s')
+    deriving (Functor)
 
 instance Applicative FCode where
     pure val = FCode (\_info_down state -> (val, state))