Remove redundant constraints in the compiler itself, found by -fwarn-redundant-constraints

25 files changed, 79 insertions, 69 deletions

diff --git a/compiler/basicTypes/Name.hs b/compiler/basicTypes/Name.hs
index ffdd1a14d8..3b0da643ba 100644
--- a/compiler/basicTypes/Name.hs
+++ b/compiler/basicTypes/Name.hs
@@ -564,11 +564,12 @@ getSrcLoc           = nameSrcLoc           . getName
 getSrcSpan          = nameSrcSpan          . getName
 getOccString        = occNameString        . getOccName
 
-pprInfixName, pprPrefixName :: (Outputable a, NamedThing a) => a -> SDoc
+pprInfixName :: (Outputable a, NamedThing a) => a -> SDoc
 -- See Outputable.pprPrefixVar, pprInfixVar;
 -- add parens or back-quotes as appropriate
 pprInfixName  n = pprInfixVar (isSymOcc (getOccName n)) (ppr n)
 
+pprPrefixName :: NamedThing a => a -> SDoc
 pprPrefixName thing
  |  name `hasKey` liftedTypeKindTyConKey
  = ppr name   -- See Note [Special treatment for kind *]
diff --git a/compiler/cmm/CmmExpr.hs b/compiler/cmm/CmmExpr.hs
index 4d9bbf8915..aa5cef1ebb 100644
--- a/compiler/cmm/CmmExpr.hs
+++ b/compiler/cmm/CmmExpr.hs
@@ -280,15 +280,15 @@ type RegSet r     = Set r
 type LocalRegSet  = RegSet LocalReg
 type GlobalRegSet = RegSet GlobalReg
 
-emptyRegSet             :: Ord r => RegSet r
-nullRegSet              :: Ord r => RegSet r -> Bool
+emptyRegSet             :: RegSet r
+nullRegSet              :: RegSet r -> Bool
 elemRegSet              :: Ord r => r -> RegSet r -> Bool
 extendRegSet            :: Ord r => RegSet r -> r -> RegSet r
 deleteFromRegSet        :: Ord r => RegSet r -> r -> RegSet r
 mkRegSet                :: Ord r => [r] -> RegSet r
 minusRegSet, plusRegSet, timesRegSet :: Ord r => RegSet r -> RegSet r -> RegSet r
-sizeRegSet              :: Ord r => RegSet r -> Int
-regSetToList            :: Ord r => RegSet r -> [r]
+sizeRegSet              :: RegSet r -> Int
+regSetToList            :: RegSet r -> [r]
 
 emptyRegSet      = Set.empty
 nullRegSet       = Set.null
diff --git a/compiler/cmm/Hoopl/Dataflow.hs b/compiler/cmm/Hoopl/Dataflow.hs
index 4fbf42e607..29c7afedb4 100644
--- a/compiler/cmm/Hoopl/Dataflow.hs
+++ b/compiler/cmm/Hoopl/Dataflow.hs
@@ -763,7 +763,7 @@ normalizeGraph g = (mapGraphBlocks dropFact g, facts g)
           exitFacts (JustO (DBlock f b)) = mapSingleton (entryLabel b) f
           bodyFacts :: LabelMap (DBlock f n C C) -> FactBase f
           bodyFacts body = mapFoldWithKey f noFacts body
-            where f :: forall t a x. (NonLocal t) => Label -> DBlock a t C x -> LabelMap a -> LabelMap a
+            where f :: forall t a x. Label -> DBlock a t C x -> LabelMap a -> LabelMap a
                   f lbl (DBlock f _) fb = mapInsert lbl f fb
 
 --- implementation of the constructors (boring)
diff --git a/compiler/coreSyn/TrieMap.hs b/compiler/coreSyn/TrieMap.hs
index efae2865cd..9197386ccb 100644
--- a/compiler/coreSyn/TrieMap.hs
+++ b/compiler/coreSyn/TrieMap.hs
@@ -154,12 +154,12 @@ mapMb :: TrieMap m => (a->b) -> MaybeMap m a -> MaybeMap m b
 mapMb f (MM { mm_nothing = mn, mm_just = mj })
   = MM { mm_nothing = fmap f mn, mm_just = mapTM f mj }
 
-lkMaybe :: TrieMap m => (forall b. k -> m b -> Maybe b)
+lkMaybe :: (forall b. k -> m b -> Maybe b)
         -> Maybe k -> MaybeMap m a -> Maybe a
 lkMaybe _  Nothing  = mm_nothing
 lkMaybe lk (Just x) = mm_just >.> lk x
 
-xtMaybe :: TrieMap m => (forall b. k -> XT b -> m b -> m b)
+xtMaybe :: (forall b. k -> XT b -> m b -> m b)
         -> Maybe k -> XT a -> MaybeMap m a -> MaybeMap m a
 xtMaybe _  Nothing  f m = m { mm_nothing  = f (mm_nothing m) }
 xtMaybe tr (Just x) f m = m { mm_just = mm_just m |> tr x f }
diff --git a/compiler/deSugar/MatchLit.hs b/compiler/deSugar/MatchLit.hs
index 1f54780c6d..914b21016c 100644
--- a/compiler/deSugar/MatchLit.hs
+++ b/compiler/deSugar/MatchLit.hs
@@ -394,7 +394,7 @@ hsLitKey _      (HsString _ s)     = MachStr    (fastStringToByteString s)
 hsLitKey _      l                  = pprPanic "hsLitKey" (ppr l)
 
 ---------------------------
-hsOverLitKey :: OutputableBndr a => HsOverLit a -> Bool -> Literal
+hsOverLitKey :: HsOverLit a -> Bool -> Literal
 -- Ditto for HsOverLit; the boolean indicates to negate
 hsOverLitKey (OverLit { ol_val = l }) neg = litValKey l neg
 
diff --git a/compiler/ghci/ByteCodeItbls.hs b/compiler/ghci/ByteCodeItbls.hs
index d6399baf64..872d728992 100644
--- a/compiler/ghci/ByteCodeItbls.hs
+++ b/compiler/ghci/ByteCodeItbls.hs
@@ -235,12 +235,14 @@ mkJumpToAddr dflags a = case platformArch (targetPlatform dflags) of
     arch ->
         panic ("mkJumpToAddr not defined for " ++ show arch)
 
-byte0, byte1, byte2, byte3 :: (Integral w, Bits w) => w -> Word8
+byte0 :: (Integral w) => w -> Word8
 byte0 w = fromIntegral w
+
+byte1, byte2, byte3, byte4, byte5, byte6, byte7
+       :: (Integral w, Bits w) => w -> Word8
 byte1 w = fromIntegral (w `shiftR` 8)
 byte2 w = fromIntegral (w `shiftR` 16)
 byte3 w = fromIntegral (w `shiftR` 24)
-byte4, byte5, byte6, byte7 :: (Integral w, Bits w) => w -> Word8
 byte4 w = fromIntegral (w `shiftR` 32)
 byte5 w = fromIntegral (w `shiftR` 40)
 byte6 w = fromIntegral (w `shiftR` 48)
diff --git a/compiler/ghci/Linker.hs b/compiler/ghci/Linker.hs
index 91706da7cb..5a32d0761d 100644
--- a/compiler/ghci/Linker.hs
+++ b/compiler/ghci/Linker.hs
@@ -199,7 +199,7 @@ linkDependencies hsc_env pls span needed_mods = do
 
 -- | Temporarily extend the linker state.
 
-withExtendedLinkEnv :: (MonadIO m, ExceptionMonad m) =>
+withExtendedLinkEnv :: (ExceptionMonad m) =>
                        [(Name,HValue)] -> m a -> m a
 withExtendedLinkEnv new_env action
     = gbracket (liftIO $ extendLinkEnv new_env)
diff --git a/compiler/hsSyn/HsDecls.hs b/compiler/hsSyn/HsDecls.hs
index f81d0a1ece..4b54a8d702 100644
--- a/compiler/hsSyn/HsDecls.hs
+++ b/compiler/hsSyn/HsDecls.hs
@@ -601,12 +601,10 @@ isDataFamilyDecl _other      = False
 
 -- Dealing with names
 
-tyFamInstDeclName :: OutputableBndr name
-                  => TyFamInstDecl name -> name
+tyFamInstDeclName :: TyFamInstDecl name -> name
 tyFamInstDeclName = unLoc . tyFamInstDeclLName
 
-tyFamInstDeclLName :: OutputableBndr name
-                   => TyFamInstDecl name -> Located name
+tyFamInstDeclLName :: TyFamInstDecl name -> Located name
 tyFamInstDeclLName (TyFamInstDecl { tfid_eqn =
                      (L _ (TyFamEqn { tfe_tycon = ln })) })
   = ln
@@ -618,7 +616,7 @@ tyClDeclLName decl = tcdLName decl
 tcdName :: TyClDecl name -> name
 tcdName = unLoc . tyClDeclLName
 
-tyClDeclTyVars :: OutputableBndr name => TyClDecl name -> LHsTyVarBndrs name
+tyClDeclTyVars :: TyClDecl name -> LHsTyVarBndrs name
 tyClDeclTyVars (FamDecl { tcdFam = FamilyDecl { fdTyVars = tvs } }) = tvs
 tyClDeclTyVars d = tcdTyVars d
 
diff --git a/compiler/hsSyn/HsExpr.hs b/compiler/hsSyn/HsExpr.hs
index 384222b6a0..a5a1aaf4b8 100644
--- a/compiler/hsSyn/HsExpr.hs
+++ b/compiler/hsSyn/HsExpr.hs
@@ -1064,14 +1064,14 @@ pprMatch ctxt (Match pats maybe_ty grhss)
                         Nothing -> empty
 
 
-pprGRHSs :: (OutputableBndr idL, OutputableBndr idR, Outputable body)
+pprGRHSs :: (OutputableBndr idR, Outputable body)
          => HsMatchContext idL -> GRHSs idR body -> SDoc
 pprGRHSs ctxt (GRHSs grhss binds)
   = vcat (map (pprGRHS ctxt . unLoc) grhss)
  $$ ppUnless (isEmptyLocalBinds binds)
       (text "where" $$ nest 4 (pprBinds binds))
 
-pprGRHS :: (OutputableBndr idL, OutputableBndr idR, Outputable body)
+pprGRHS :: (OutputableBndr idR, Outputable body)
         => HsMatchContext idL -> GRHS idR body -> SDoc
 pprGRHS ctxt (GRHS [] body)
  =  pp_rhs ctxt body
@@ -1355,8 +1355,8 @@ In any other context than 'MonadComp', the fields for most of these
 'SyntaxExpr's stay bottom.
 -}
 
-instance (OutputableBndr idL, OutputableBndr idR)
-    => Outputable (ParStmtBlock idL idR) where
+instance (OutputableBndr idL)
+      => Outputable (ParStmtBlock idL idR) where
   ppr (ParStmtBlock stmts _ _) = interpp'SP stmts
 
 instance (OutputableBndr idL, OutputableBndr idR, Outputable body)
diff --git a/compiler/main/CmdLineParser.hs b/compiler/main/CmdLineParser.hs
index 94c786b567..0f7d45df27 100644
--- a/compiler/main/CmdLineParser.hs
+++ b/compiler/main/CmdLineParser.hs
@@ -108,7 +108,7 @@ instance Monad m => Monad (EwM m) where
                                       unEwM (k r) l e' w')
     return v = EwM (\_ e w -> return (e, w, v))
 
-setArg :: Monad m => Located String -> EwM m () -> EwM m ()
+setArg :: Located String -> EwM m () -> EwM m ()
 setArg l (EwM f) = EwM (\_ es ws -> f l es ws)
 
 addErr :: Monad m => String -> EwM m ()
diff --git a/compiler/main/GHC.hs b/compiler/main/GHC.hs
index 6462aa648a..539961be90 100644
--- a/compiler/main/GHC.hs
+++ b/compiler/main/GHC.hs
@@ -345,7 +345,7 @@ import Prelude hiding (init)
 -- Unless you want to handle exceptions yourself, you should wrap this around
 -- the top level of your program.  The default handlers output the error
 -- message(s) to stderr and exit cleanly.
-defaultErrorHandler :: (ExceptionMonad m, MonadIO m)
+defaultErrorHandler :: (ExceptionMonad m)
                     => FatalMessager -> FlushOut -> m a -> m a
 defaultErrorHandler fm (FlushOut flushOut) inner =
   -- top-level exception handler: any unrecognised exception is a compiler bug.
@@ -386,7 +386,7 @@ defaultErrorHandler fm (FlushOut flushOut) inner =
 -- a GHC run.  This is separate from 'defaultErrorHandler', because you might
 -- want to override the error handling, but still get the ordinary cleanup
 -- behaviour.
-defaultCleanupHandler :: (ExceptionMonad m, MonadIO m) =>
+defaultCleanupHandler :: (ExceptionMonad m) =>
                          DynFlags -> m a -> m a
 defaultCleanupHandler dflags inner =
     -- make sure we clean up after ourselves
@@ -432,7 +432,11 @@ runGhc mb_top_dir ghc = do
 -- to this function will create a new session which should not be shared among
 -- several threads.
 
-runGhcT :: (ExceptionMonad m, Functor m, MonadIO m) =>
+#if __GLASGOW_HASKELL__ < 710
+runGhcT :: (ExceptionMonad m, Functor m) =>
+#else
+runGhcT :: (ExceptionMonad m) =>
+#endif
            Maybe FilePath  -- ^ See argument to 'initGhcMonad'.
         -> GhcT m a        -- ^ The action to perform.
         -> m a
diff --git a/compiler/main/GhcMonad.hs b/compiler/main/GhcMonad.hs
index ebcaf368e1..6a3e107801 100644
--- a/compiler/main/GhcMonad.hs
+++ b/compiler/main/GhcMonad.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE CPP, RankNTypes #-}
 {-# OPTIONS_GHC -funbox-strict-fields #-}
 -- -----------------------------------------------------------------------------
 --
@@ -156,7 +156,8 @@ 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 }
-liftGhcT :: Monad m => m a -> GhcT m a
+
+liftGhcT :: m a -> GhcT m a
 liftGhcT m = GhcT $ \_ -> m
 
 instance Functor m => Functor (GhcT m) where
@@ -183,10 +184,18 @@ instance ExceptionMonad m => ExceptionMonad (GhcT m) where
                            in
                               unGhcT (f g_restore) s
 
-instance (Functor m, ExceptionMonad m, MonadIO m) => HasDynFlags (GhcT m) where
+#if __GLASGOW_HASKELL__ < 710
+instance (ExceptionMonad m, Functor m) => HasDynFlags (GhcT m) where
+#else
+instance (ExceptionMonad m) => HasDynFlags (GhcT m) where
+#endif
   getDynFlags = getSessionDynFlags
 
-instance (Functor m, ExceptionMonad m, MonadIO m) => GhcMonad (GhcT m) where
+#if __GLASGOW_HASKELL__ < 710
+instance (ExceptionMonad m, Functor m) => GhcMonad (GhcT m) where
+#else
+instance (ExceptionMonad m) => GhcMonad (GhcT m) where
+#endif
   getSession = GhcT $ \(Session r) -> liftIO $ readIORef r
   setSession s' = GhcT $ \(Session r) -> liftIO $ writeIORef r s'
 
diff --git a/compiler/main/InteractiveEval.hs b/compiler/main/InteractiveEval.hs
index 6f16d4ef0c..959b7e83a9 100644
--- a/compiler/main/InteractiveEval.hs
+++ b/compiler/main/InteractiveEval.hs
@@ -75,7 +75,6 @@ import BreakArray
 import RtClosureInspect
 import Outputable
 import FastString
-import MonadUtils
 
 import System.Mem.Weak
 import System.Directory
@@ -427,7 +426,7 @@ rethrow dflags io = Exception.catch io $ \se -> do
 -- resets everything when the computation has stopped running.  This
 -- is a not-very-good way to ensure that only the interactive
 -- evaluation should generate breakpoints.
-withBreakAction :: (ExceptionMonad m, MonadIO m) =>
+withBreakAction :: (ExceptionMonad m) =>
                    Bool -> DynFlags -> MVar () -> MVar Status -> m a -> m a
 withBreakAction step dflags breakMVar statusMVar act
  = gbracket (liftIO setBreakAction) (liftIO . resetBreakAction) (\_ -> act)
diff --git a/compiler/nativeGen/RegAlloc/Graph/SpillClean.hs b/compiler/nativeGen/RegAlloc/Graph/SpillClean.hs
index a81d76dd8d..01ab3efff1 100644
--- a/compiler/nativeGen/RegAlloc/Graph/SpillClean.hs
+++ b/compiler/nativeGen/RegAlloc/Graph/SpillClean.hs
@@ -543,7 +543,7 @@ addAssoc a b m
 
 
 -- | Delete all associations to a node.
-delAssoc :: (Outputable a, Uniquable a)
+delAssoc :: (Uniquable a)
          => a -> Assoc a -> Assoc a
 
 delAssoc a m
@@ -566,7 +566,7 @@ delAssoc1 a b m
 
 
 -- | Check if these two things are associated.
-elemAssoc :: (Outputable a, Uniquable a)
+elemAssoc :: (Uniquable a)
           => a -> a -> Assoc a -> Bool
 
 elemAssoc a b m
@@ -574,7 +574,7 @@ elemAssoc a b m
 
 
 -- | Find the refl. trans. closure of the association from this point.
-closeAssoc :: (Outputable a, Uniquable a)
+closeAssoc :: (Uniquable a)
         => a -> Assoc a -> UniqSet a
 
 closeAssoc a assoc
@@ -604,10 +604,7 @@ closeAssoc a assoc
                         (unionUniqSets   toVisit neighbors)
 
 -- | Intersect two associations.
-intersectAssoc
-        :: Uniquable a
-        => Assoc a -> Assoc a -> Assoc a
-
+intersectAssoc :: Assoc a -> Assoc a -> Assoc a
 intersectAssoc a b
         = intersectUFM_C (intersectUniqSets) a b
 
diff --git a/compiler/nativeGen/RegAlloc/Linear/Main.hs b/compiler/nativeGen/RegAlloc/Linear/Main.hs
index d602d60d10..434c00f9b8 100644
--- a/compiler/nativeGen/RegAlloc/Linear/Main.hs
+++ b/compiler/nativeGen/RegAlloc/Linear/Main.hs
@@ -606,7 +606,7 @@ releaseRegs regs = do
 --
 
 saveClobberedTemps
-        :: (Outputable instr, Instruction instr, FR freeRegs)
+        :: (Instruction instr, FR freeRegs)
         => [RealReg]            -- real registers clobbered by this instruction
         -> [Reg]                -- registers which are no longer live after this insn
         -> RegM freeRegs [instr]         -- return: instructions to spill any temps that will
@@ -873,7 +873,7 @@ newLocation _ my_reg = InReg my_reg
 
 -- | Load up a spilled temporary if we need to (read from memory).
 loadTemp
-        :: (Outputable instr, Instruction instr)
+        :: (Instruction instr)
         => VirtualReg   -- the temp being loaded
         -> SpillLoc     -- the current location of this temp
         -> RealReg      -- the hreg to load the temp into
diff --git a/compiler/nativeGen/SPARC/Base.hs b/compiler/nativeGen/SPARC/Base.hs
index 96fb5e7797..a57d5e1c9a 100644
--- a/compiler/nativeGen/SPARC/Base.hs
+++ b/compiler/nativeGen/SPARC/Base.hs
@@ -66,7 +66,7 @@ is32BitInteger i
 
 
 -- | Sadness.
-largeOffsetError :: (Integral a, Show a) => a -> b
+largeOffsetError :: (Show a) => a -> b
 largeOffsetError i
   = panic ("ERROR: SPARC native-code generator cannot handle large offset ("
                 ++ show i ++ ");\nprobably because of large constant data structures;" ++
diff --git a/compiler/typecheck/TcRnMonad.hs b/compiler/typecheck/TcRnMonad.hs
index 31391e4082..0f98726db8 100644
--- a/compiler/typecheck/TcRnMonad.hs
+++ b/compiler/typecheck/TcRnMonad.hs
@@ -893,10 +893,11 @@ failIfErrsM :: TcRn ()
 -- Useful to avoid error cascades
 failIfErrsM = ifErrsM failM (return ())
 
-checkTH :: Outputable a => a -> String -> TcRn ()
 #ifdef GHCI
+checkTH :: a -> String -> TcRn ()
 checkTH _ _ = return () -- OK
 #else
+checkTH :: Outputable a => a -> String -> TcRn ()
 checkTH e what = failTH e what  -- Raise an error in a stage-1 compiler
 #endif
 
diff --git a/compiler/types/CoAxiom.hs b/compiler/types/CoAxiom.hs
index a3e2bb220a..78cc6ba450 100644
--- a/compiler/types/CoAxiom.hs
+++ b/compiler/types/CoAxiom.hs
@@ -184,7 +184,7 @@ brListFoldlM_ :: forall a b m br. Monad m
               => (a -> b -> m a) -> a -> BranchList b br -> m ()
 brListFoldlM_ f z brs = do { _ <- go z brs
                            ; return () }
-  where go :: forall br'. Monad m => a -> BranchList b br' -> m a
+  where go :: forall br'. a -> BranchList b br' -> m a
         go acc (FirstBranch b)  = f acc b
         go acc (NextBranch h t) = do { fh <- f acc h
                                      ; go fh t }
diff --git a/compiler/utils/Binary.hs b/compiler/utils/Binary.hs
index 1e85a73d0e..a83e613029 100644
--- a/compiler/utils/Binary.hs
+++ b/compiler/utils/Binary.hs
@@ -549,7 +549,7 @@ writeByteArray arr i (W8# w) = IO $ \s ->
 indexByteArray :: ByteArray# -> Int# -> Word8
 indexByteArray a# n# = W8# (indexWord8Array# a# n#)
 
-instance (Integral a, Binary a) => Binary (Ratio a) where
+instance (Binary a) => Binary (Ratio a) where
     put_ bh (a :% b) = do put_ bh a; put_ bh b
     get bh = do a <- get bh; b <- get bh; return (a :% b)
 
diff --git a/compiler/utils/GraphColor.hs b/compiler/utils/GraphColor.hs
index 7ba8efbd03..41b367692a 100644
--- a/compiler/utils/GraphColor.hs
+++ b/compiler/utils/GraphColor.hs
@@ -34,7 +34,7 @@ import Data.List
 --
 colorGraph
         :: ( Uniquable  k, Uniquable cls,  Uniquable  color
-           , Eq color, Eq cls, Ord k
+           , Eq cls, Ord k
            , Outputable k, Outputable cls, Outputable color)
         => Bool                         -- ^ whether to do iterative coalescing
         -> Int                          -- ^ how many times we've tried to color this graph so far.
@@ -250,7 +250,7 @@ colorScan_spill iterative triv spill graph
 
 assignColors
         :: ( Uniquable k, Uniquable cls, Uniquable color
-           , Eq color, Outputable cls)
+           , Outputable cls)
         => UniqFM (UniqSet color)       -- ^ map of (node class -> set of colors available for this class).
         -> Graph k cls color            -- ^ the graph
         -> [k]                          -- ^ nodes to assign a color to.
@@ -288,7 +288,7 @@ assignColors colors graph ks
 --
 selectColor
         :: ( Uniquable k, Uniquable cls, Uniquable color
-           , Eq color, Outputable cls)
+           , Outputable cls)
         => UniqFM (UniqSet color)       -- ^ map of (node class -> set of colors available for this class).
         -> Graph k cls color            -- ^ the graph
         -> k                            -- ^ key of the node to select a color for.
diff --git a/compiler/utils/GraphOps.hs b/compiler/utils/GraphOps.hs
index 7bf3ecdffb..804153dad2 100644
--- a/compiler/utils/GraphOps.hs
+++ b/compiler/utils/GraphOps.hs
@@ -76,7 +76,7 @@ addNode k node graph
 
 
 -- | Delete a node and all its edges from the graph.
-delNode :: (Uniquable k, Outputable k)
+delNode :: (Uniquable k)
         => k -> Graph k cls color -> Maybe (Graph k cls color)
 
 delNode k graph
@@ -119,16 +119,14 @@ modNode f k graph
 
 
 -- | Get the size of the graph, O(n)
-size    :: Uniquable k
-        => Graph k cls color -> Int
+size    :: Graph k cls color -> Int
 
 size graph
         = sizeUFM $ graphMap graph
 
 
 -- | Union two graphs together.
-union   :: Uniquable k
-        => Graph k cls color -> Graph k cls color -> Graph k cls color
+union   :: Graph k cls color -> Graph k cls color -> Graph k cls color
 
 union   graph1 graph2
         = Graph
@@ -333,7 +331,7 @@ coalesceGraph' aggressive triv graph kkPairsAcc
 --               Nothing if either of the nodes weren't in the graph
 
 coalesceNodes
-        :: (Uniquable k, Ord k, Eq cls, Outputable k)
+        :: (Uniquable k, Ord k, Eq cls)
         => Bool                 -- ^ If True, coalesce nodes even if this might make the graph
                                 --      less colorable (aggressive coalescing)
         -> Triv  k cls color
@@ -364,7 +362,7 @@ coalesceNodes aggressive triv graph (k1, k2)
         = (graph, Nothing)
 
 coalesceNodes_merge
-        :: (Uniquable k, Ord k, Eq cls, Outputable k)
+        :: (Uniquable k, Eq cls)
         => Bool
         -> Triv  k cls color
         -> Graph k cls color
@@ -410,7 +408,7 @@ coalesceNodes_merge aggressive triv graph kMin kMax nMin nMax
           in    coalesceNodes_check aggressive triv graph kMin kMax node
 
 coalesceNodes_check
-        :: (Uniquable k, Ord k, Eq cls, Outputable k)
+        :: Uniquable k
         => Bool
         -> Triv  k cls color
         -> Graph k cls color
@@ -483,7 +481,7 @@ freezeNode k
 --              right here, and add it to a worklist if known triv\/non-move nodes.
 --
 freezeOneInGraph
-        :: (Uniquable k, Outputable k)
+        :: (Uniquable k)
         => Graph k cls color
         -> ( Graph k cls color          -- the new graph
            , Bool )                     -- whether we found a node to freeze
@@ -512,7 +510,7 @@ freezeOneInGraph graph
 --      for debugging the iterative allocator.
 --
 freezeAllInGraph
-        :: (Uniquable k, Outputable k)
+        :: (Uniquable k)
         => Graph k cls color
         -> Graph k cls color
 
@@ -525,8 +523,7 @@ freezeAllInGraph graph
 -- | Find all the nodes in the graph that meet some criteria
 --
 scanGraph
-        :: Uniquable k
-        => (Node k cls color -> Bool)
+        :: (Node k cls color -> Bool)
         -> Graph k cls color
         -> [Node k cls color]
 
@@ -611,8 +608,7 @@ checkNode graph node
 -- | Slurp out a map of how many nodes had a certain number of conflict neighbours
 
 slurpNodeConflictCount
-        :: Uniquable k
-        => Graph k cls color
+        :: Graph k cls color
         -> UniqFM (Int, Int)    -- ^ (conflict neighbours, num nodes with that many conflicts)
 
 slurpNodeConflictCount graph
diff --git a/compiler/utils/GraphPpr.hs b/compiler/utils/GraphPpr.hs
index df85fddc5b..6f7e9d5bb2 100644
--- a/compiler/utils/GraphPpr.hs
+++ b/compiler/utils/GraphPpr.hs
@@ -20,7 +20,7 @@ import Data.Maybe
 
 -- | Pretty print a graph in a somewhat human readable format.
 dumpGraph
-        :: (Outputable k, Outputable cls, Outputable color)
+        :: (Outputable k, Outputable color)
         => Graph k cls color -> SDoc
 
 dumpGraph graph
@@ -28,7 +28,7 @@ dumpGraph graph
         $$ (vcat $ map dumpNode $ eltsUFM $ graphMap graph)
 
 dumpNode
-        :: (Outputable k, Outputable cls, Outputable color)
+        :: (Outputable k, Outputable color)
         => Node k cls color -> SDoc
 
 dumpNode node
@@ -74,8 +74,7 @@ dotGraph colorMap triv graph
                    , space ])
 
 
-dotNode :: ( Uniquable k
-           , Outputable k, Outputable cls, Outputable color)
+dotNode :: ( Outputable k, Outputable cls, Outputable color)
         => (color -> SDoc)
         -> Triv k cls color
         -> Node k cls color -> SDoc
@@ -132,7 +131,7 @@ dotNode colorMap triv node
 
 dotNodeEdges
         :: ( Uniquable k
-           , Outputable k, Outputable cls, Outputable color)
+           , Outputable k)
         => UniqSet k
         -> Node k cls color
         -> (UniqSet k, Maybe SDoc)
diff --git a/compiler/utils/Maybes.hs b/compiler/utils/Maybes.hs
index fc8e3199ae..f5083fdab5 100644
--- a/compiler/utils/Maybes.hs
+++ b/compiler/utils/Maybes.hs
@@ -67,7 +67,11 @@ newtype MaybeT m a = MaybeT {runMaybeT :: m (Maybe a)}
 instance Functor m => Functor (MaybeT m) where
   fmap f x = MaybeT $ fmap (fmap f) $ runMaybeT x
 
+#if __GLASGOW_HASKELL__ < 710
 instance (Monad m, Functor m) => Applicative (MaybeT m) where
+#else
+instance (Monad m) => Applicative (MaybeT m) where
+#endif
   pure  = return
   (<*>) = ap
 
diff --git a/compiler/utils/Serialized.hs b/compiler/utils/Serialized.hs
index b1576a087f..d4e0048467 100644
--- a/compiler/utils/Serialized.hs
+++ b/compiler/utils/Serialized.hs
@@ -100,7 +100,7 @@ deserializeConstr bytes k = deserializeWord8 bytes $ \constr_ix bytes ->
 serializeFixedWidthNum :: forall a. (Num a, Integral a, Bits a) => a -> [Word8] -> [Word8]
 serializeFixedWidthNum what = go (bitSize what) what
 #else
-serializeFixedWidthNum :: forall a. (Num a, Integral a, FiniteBits a) => a -> [Word8] -> [Word8]
+serializeFixedWidthNum :: forall a. (Integral a, FiniteBits a) => a -> [Word8] -> [Word8]
 serializeFixedWidthNum what = go (finiteBitSize what) what
 #endif
   where
@@ -113,7 +113,7 @@ serializeFixedWidthNum what = go (finiteBitSize what) what
 deserializeFixedWidthNum :: forall a b. (Num a, Integral a, Bits a) => [Word8] -> (a -> [Word8] -> b) -> b
 deserializeFixedWidthNum bytes k = go (bitSize (undefined :: a)) bytes k
 #else
-deserializeFixedWidthNum :: forall a b. (Num a, Integral a, FiniteBits a) => [Word8] -> (a -> [Word8] -> b) -> b
+deserializeFixedWidthNum :: forall a b. (Integral a, FiniteBits a) => [Word8] -> (a -> [Word8] -> b) -> b
 deserializeFixedWidthNum bytes k = go (finiteBitSize (undefined :: a)) bytes k
 #endif
   where
diff --git a/compiler/utils/UniqSet.hs b/compiler/utils/UniqSet.hs
index 5a82303157..4ceeec0000 100644
--- a/compiler/utils/UniqSet.hs
+++ b/compiler/utils/UniqSet.hs
@@ -54,7 +54,7 @@ addOneToUniqSet_C :: Uniquable a => (a -> a -> a) -> UniqSet a -> a -> UniqSet a
 addListToUniqSet :: Uniquable a => UniqSet a -> [a] -> UniqSet a
 
 delOneFromUniqSet :: Uniquable a => UniqSet a -> a -> UniqSet a
-delOneFromUniqSet_Directly :: Uniquable a => UniqSet a -> Unique -> UniqSet a
+delOneFromUniqSet_Directly :: UniqSet a -> Unique -> UniqSet a
 delListFromUniqSet :: Uniquable a => UniqSet a -> [a] -> UniqSet a
 
 unionUniqSets :: UniqSet a -> UniqSet a -> UniqSet a