Use DeriveFunctor throughout the codebase (#15654)

3 files changed, 11 insertions, 14 deletions

diff --git a/compiler/nativeGen/AsmCodeGen.hs b/compiler/nativeGen/AsmCodeGen.hs
index cc608b1ec6..ed0c57e1e2 100644
--- a/compiler/nativeGen/AsmCodeGen.hs
+++ b/compiler/nativeGen/AsmCodeGen.hs
@@ -6,7 +6,8 @@
 --
 -- -----------------------------------------------------------------------------
 
-{-# LANGUAGE BangPatterns, CPP, GADTs, ScopedTypeVariables, PatternSynonyms #-}
+{-# LANGUAGE BangPatterns, CPP, GADTs, ScopedTypeVariables, PatternSynonyms,
+    DeriveFunctor #-}
 
 #if !defined(GHC_LOADED_INTO_GHCI)
 {-# LANGUAGE UnboxedTuples #-}
@@ -1038,13 +1039,11 @@ pattern OptMResult x y = (# x, y #)
 {-# COMPLETE OptMResult #-}
 #else
 
-data OptMResult a = OptMResult !a ![CLabel]
+data OptMResult a = OptMResult !a ![CLabel] deriving (Functor)
 #endif
 
 newtype CmmOptM a = CmmOptM (DynFlags -> Module -> [CLabel] -> OptMResult a)
-
-instance Functor CmmOptM where
-    fmap = liftM
+    deriving (Functor)
 
 instance Applicative CmmOptM where
     pure x = CmmOptM $ \_ _ imports -> OptMResult x imports
diff --git a/compiler/nativeGen/NCGMonad.hs b/compiler/nativeGen/NCGMonad.hs
index 0f53ef6690..3680c1c7b0 100644
--- a/compiler/nativeGen/NCGMonad.hs
+++ b/compiler/nativeGen/NCGMonad.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE DeriveFunctor #-}
 
 -- -----------------------------------------------------------------------------
 --
@@ -59,7 +60,7 @@ import Unique           ( Unique )
 import DynFlags
 import Module
 
-import Control.Monad    ( liftM, ap )
+import Control.Monad    ( ap )
 
 import Instruction
 import Outputable (SDoc, pprPanic, ppr)
@@ -113,6 +114,7 @@ data NatM_State
 type DwarfFiles = UniqFM (FastString, Int)
 
 newtype NatM result = NatM (NatM_State -> (result, NatM_State))
+    deriving (Functor)
 
 unNat :: NatM a -> NatM_State -> (a, NatM_State)
 unNat (NatM a) = a
@@ -138,9 +140,6 @@ initNat :: NatM_State -> NatM a -> (a, NatM_State)
 initNat init_st m
         = case unNat m init_st of { (r,st) -> (r,st) }
 
-instance Functor NatM where
-      fmap = liftM
-
 instance Applicative NatM where
       pure = returnNat
       (<*>) = ap
diff --git a/compiler/nativeGen/RegAlloc/Linear/State.hs b/compiler/nativeGen/RegAlloc/Linear/State.hs
index 8df4dd04f0..43b8f6c129 100644
--- a/compiler/nativeGen/RegAlloc/Linear/State.hs
+++ b/compiler/nativeGen/RegAlloc/Linear/State.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE CPP, PatternSynonyms #-}
+{-# LANGUAGE CPP, PatternSynonyms, DeriveFunctor #-}
 
 #if !defined(GHC_LOADED_INTO_GHCI)
 {-# LANGUAGE UnboxedTuples #-}
@@ -50,7 +50,7 @@ import DynFlags
 import Unique
 import UniqSupply
 
-import Control.Monad (liftM, ap)
+import Control.Monad (ap)
 
 -- Avoids using unboxed tuples when loading into GHCi
 #if !defined(GHC_LOADED_INTO_GHCI)
@@ -63,15 +63,14 @@ pattern RA_Result a b = (# a, b #)
 #else
 
 data RA_Result freeRegs a = RA_Result {-# UNPACK #-} !(RA_State freeRegs) !a
+  deriving (Functor)
 
 #endif
 
 -- | The register allocator monad type.
 newtype RegM freeRegs a
         = RegM { unReg :: RA_State freeRegs -> RA_Result freeRegs a }
-
-instance Functor (RegM freeRegs) where
-      fmap = liftM
+        deriving (Functor)
 
 instance Applicative (RegM freeRegs) where
       pure a  =  RegM $ \s -> RA_Result s a