6 files changed, 13 insertions, 25 deletions
diff --git a/compiler/main/Annotations.hs b/compiler/main/Annotations.hs
index f6d5a1cb12..82d80aae43 100644
--- a/compiler/main/Annotations.hs
+++ b/compiler/main/Annotations.hs
@@ -4,6 +4,7 @@
 -- (c) The University of Glasgow 2006
 -- (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 --
+{-# LANGUAGE DeriveFunctor #-}
 module Annotations (
         -- * Main Annotation data types
         Annotation(..), AnnPayload,
@@ -49,14 +50,11 @@ data AnnTarget name
   = NamedTarget name          -- ^ We are annotating something with a name:
                               --      a type or identifier
   | ModuleTarget Module       -- ^ We are annotating a particular module
+  deriving (Functor)
 
 -- | The kind of annotation target found in the middle end of the compiler
 type CoreAnnTarget = AnnTarget Name
 
-instance Functor AnnTarget where
-    fmap f (NamedTarget nm) = NamedTarget (f nm)
-    fmap _ (ModuleTarget mod) = ModuleTarget mod
-
 -- | Get the 'name' of an annotation target if it exists.
 getAnnTargetName_maybe :: AnnTarget name -> Maybe name
 getAnnTargetName_maybe (NamedTarget nm) = Just nm
diff --git a/compiler/main/CmdLineParser.hs b/compiler/main/CmdLineParser.hs
index 6763aed128..d2cc56f033 100644
--- a/compiler/main/CmdLineParser.hs
+++ b/compiler/main/CmdLineParser.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE DeriveFunctor #-}
 
 -------------------------------------------------------------------------------
 --
@@ -166,9 +167,7 @@ liftEwM action = EwM (\_ es ws -> do { r <- action; return (es, ws, r) })
 
 -- (CmdLineP s) typically instantiates the 'm' in (EwM m) and (OptKind m)
 newtype CmdLineP s a = CmdLineP { runCmdLine :: s -> (a, s) }
-
-instance Functor (CmdLineP s) where
-    fmap = liftM
+    deriving (Functor)
 
 instance Applicative (CmdLineP s) where
     pure a = CmdLineP $ \s -> (a, s)
diff --git a/compiler/main/GhcMonad.hs b/compiler/main/GhcMonad.hs
index f72cacc7ef..846744c439 100644
--- a/compiler/main/GhcMonad.hs
+++ b/compiler/main/GhcMonad.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE CPP, RankNTypes #-}
+{-# LANGUAGE CPP, DeriveFunctor, RankNTypes #-}
 {-# OPTIONS_GHC -funbox-strict-fields #-}
 -- -----------------------------------------------------------------------------
 --
@@ -90,7 +90,7 @@ logWarnings warns = do
 -- | A minimal implementation of a 'GhcMonad'.  If you need a custom monad,
 -- e.g., to maintain additional state consider wrapping this monad or using
 -- 'GhcT'.
-newtype Ghc a = Ghc { unGhc :: Session -> IO a }
+newtype Ghc a = Ghc { unGhc :: Session -> IO a } deriving (Functor)
 
 -- | The Session is a handle to the complete state of a compilation
 -- session.  A compilation session consists of a set of modules
@@ -98,9 +98,6 @@ newtype Ghc a = Ghc { unGhc :: Session -> IO a }
 -- interactive evaluation, and various caches.
 data Session = Session !(IORef HscEnv)
 
-instance Functor Ghc where
-  fmap f m = Ghc $ \s -> f `fmap` unGhc m s
-
 instance Applicative Ghc where
   pure a = Ghc $ \_ -> return a
   g <*> m = do f <- g; a <- m; return (f a)
@@ -158,13 +155,11 @@ reifyGhc act = Ghc $ act
 --
 -- Note that the wrapped monad must support IO and handling of exceptions.
 newtype GhcT m a = GhcT { unGhcT :: Session -> m a }
+    deriving (Functor)
 
 liftGhcT :: m a -> GhcT m a
 liftGhcT m = GhcT $ \_ -> m
 
-instance Functor m => Functor (GhcT m) where
-  fmap f m = GhcT $ \s -> f `fmap` unGhcT m s
-
 instance Applicative m => Applicative (GhcT m) where
   pure x  = GhcT $ \_ -> pure x
   g <*> m = GhcT $ \s -> unGhcT g s <*> unGhcT m s
diff --git a/compiler/main/HscTypes.hs b/compiler/main/HscTypes.hs
index eb9877b096..2749073ff1 100644
--- a/compiler/main/HscTypes.hs
+++ b/compiler/main/HscTypes.hs
@@ -5,6 +5,7 @@
 -}
 
 {-# LANGUAGE CPP, ScopedTypeVariables #-}
+{-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE ViewPatterns #-}
 
@@ -231,9 +232,7 @@ data HscStatus
 -- The Hsc monad: Passing an environment and warning state
 
 newtype Hsc a = Hsc (HscEnv -> WarningMessages -> IO (a, WarningMessages))
-
-instance Functor Hsc where
-    fmap = liftM
+    deriving (Functor)
 
 instance Applicative Hsc where
     pure a = Hsc $ \_ w -> return (a, w)
diff --git a/compiler/main/PipelineMonad.hs b/compiler/main/PipelineMonad.hs
index bbb1a17b65..d152d04530 100644
--- a/compiler/main/PipelineMonad.hs
+++ b/compiler/main/PipelineMonad.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE NamedFieldPuns #-}
 -- | The CompPipeline monad and associated ops
 --
@@ -22,13 +23,11 @@ import FileCleanup (TempFileLifetime)
 import Control.Monad
 
 newtype CompPipeline a = P { unP :: PipeEnv -> PipeState -> IO (PipeState, a) }
+    deriving (Functor)
 
 evalP :: CompPipeline a -> PipeEnv -> PipeState -> IO a
 evalP f env st = liftM snd $ unP f env st
 
-instance Functor CompPipeline where
-    fmap = liftM
-
 instance Applicative CompPipeline where
     pure a = P $ \_env state -> return (state, a)
     (<*>) = ap
diff --git a/compiler/main/TidyPgm.hs b/compiler/main/TidyPgm.hs
index d0e813a403..4f9c8c856f 100644
--- a/compiler/main/TidyPgm.hs
+++ b/compiler/main/TidyPgm.hs
@@ -4,7 +4,7 @@
 \section{Tidying up Core}
 -}
 
-{-# LANGUAGE CPP, ViewPatterns #-}
+{-# LANGUAGE CPP, DeriveFunctor, ViewPatterns #-}
 
 module TidyPgm (
        mkBootModDetailsTc, tidyProgram, globaliseAndTidyId
@@ -751,9 +751,7 @@ newtype DFFV a
                               -- we don't want to record these as free vars
       -> (VarSet, [Var])      -- Input State: (set, list) of free vars so far
       -> ((VarSet,[Var]),a))  -- Output state
-
-instance Functor DFFV where
-    fmap = liftM
+    deriving (Functor)
 
 instance Applicative DFFV where
     pure a = DFFV $ \_ st -> (st, a)