diff --git a/src/XMonad/Core.hs b/src/XMonad/Core.hs
index b995d28..aff0857 100644
--- a/src/XMonad/Core.hs
+++ b/src/XMonad/Core.hs
@@ -5,6 +5,7 @@
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 
 -----------------------------------------------------------------------------
 -- |
@@ -39,7 +40,7 @@ module XMonad.Core (
 import XMonad.StackSet hiding (modify)
 
 import Prelude
-import Control.Exception (fromException, try, bracket, bracket_, throw, finally, SomeException(..))
+import Control.Exception (fromException, try, bracket_, throw, finally, SomeException(..))
 import qualified Control.Exception as E
 import Control.Applicative ((<|>), empty)
 import Control.Monad.Fail
@@ -176,7 +177,7 @@ newtype Query a = Query (ReaderT Window X a)
     deriving (Functor, Applicative, Monad, MonadReader Window, MonadIO)
 
 runQuery :: Query a -> Window -> X a
-runQuery (Query m) w = runReaderT m w
+runQuery (Query m) = runReaderT m
 
 instance Semigroup a => Semigroup (Query a) where
     (<>) = liftM2 (<>)
@@ -199,7 +200,7 @@ catchX job errcase = do
     st <- get
     c <- ask
     (a, s') <- io $ runX c st job `E.catch` \e -> case fromException e of
-                        Just x -> throw e `const` (x `asTypeOf` ExitSuccess)
+                        Just (_ :: ExitCode) -> throw e
                         _ -> do hPrint stderr e; runX c st errcase
     put s'
     return a
@@ -207,12 +208,12 @@ catchX job errcase = do
 -- | Execute the argument, catching all exceptions.  Either this function or
 -- 'catchX' should be used at all callsites of user customized code.
 userCode :: X a -> X (Maybe a)
-userCode a = catchX (Just `liftM` a) (return Nothing)
+userCode a = catchX (Just <$> a) (return Nothing)
 
 -- | Same as userCode but with a default argument to return instead of using
 -- Maybe, provided for convenience.
 userCodeDef :: a -> X a -> X a
-userCodeDef defValue a = fromMaybe defValue `liftM` userCode a
+userCodeDef defValue a = fromMaybe defValue <$> userCode a
 
 -- ---------------------------------------------------------------------
 -- Convenient wrappers to state
@@ -233,7 +234,7 @@ withWindowAttributes dpy win f = do
 
 -- | True if the given window is the root window
 isRoot :: Window -> X Bool
-isRoot w = (w==) <$> asks theRoot
+isRoot w = asks $ (w ==) . theRoot
 
 -- | Wrapper for the common case of atom internment
 getAtom :: String -> X Atom
@@ -649,7 +650,7 @@ getModTime f = E.catch (Just <$> getModificationTime f) (\(SomeException _) -> r
 compile :: Directories -> Compile -> IO ExitCode
 compile dirs method =
     bracket_ uninstallSignalHandlers installSignalHandlers $
-        bracket (openFile (errFileName dirs) WriteMode) hClose $ \err -> do
+        withFile (errFileName dirs) WriteMode $ \err -> do
             let run = runProc (cfgDir dirs) err
             case method of
                 CompileGhc ->
diff --git a/src/XMonad/Main.hs b/src/XMonad/Main.hs
index b3b0213..170a019 100644
--- a/src/XMonad/Main.hs
+++ b/src/XMonad/Main.hs
@@ -503,7 +503,7 @@ grabButtons = do
     io $ ungrabButton dpy anyButton anyModifier rootw
     ems <- extraModifiers
     ba <- asks buttonActions
-    mapM_ (\(m,b) -> mapM_ (grab b . (m .|.)) ems) (M.keys $ ba)
+    mapM_ (\(m,b) -> mapM_ (grab b . (m .|.)) ems) (M.keys ba)
 
 -- | @replace@ to signals compliant window managers to exit.
 replace :: Display -> ScreenNumber -> Window -> IO ()
diff --git a/src/XMonad/Operations.hs b/src/XMonad/Operations.hs
index 95e56c5..d012436 100644
--- a/src/XMonad/Operations.hs
+++ b/src/XMonad/Operations.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE PatternGuards #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 
 -- --------------------------------------------------------------------------
 -- |
@@ -193,7 +194,7 @@ windows f = do
 
         let m   = W.floating ws
             flt = [(fw, scaleRationalRect viewrect r)
-                    | fw <- filter (flip M.member m) (W.index this)
+                    | fw <- filter (`M.member` m) (W.index this)
                     , Just r <- [M.lookup fw m]]
             vs = flt ++ rs
 
@@ -219,7 +220,7 @@ windows f = do
     -- all windows that are no longer in the windowset are marked as
     -- withdrawn, it is important to do this after the above, otherwise 'hide'
     -- will overwrite withdrawnState with iconicState
-    mapM_ (flip setWMState withdrawnState) (W.allWindows old \\ W.allWindows ws)
+    mapM_ (`setWMState` withdrawnState) (W.allWindows old \\ W.allWindows ws)
 
     isMouseFocused <- asks mouseFocused
     unless isMouseFocused $ clearEvents enterWindowMask
@@ -235,8 +236,8 @@ windowBracket :: (a -> Bool) -> X a -> X a
 windowBracket p action = withWindowSet $ \old -> do
   a <- action
   when (p a) . withWindowSet $ \new -> do
-    modifyWindowSet $ \_ -> old
-    windows         $ \_ -> new
+    modifyWindowSet $ const old
+    windows         $ const new
   return a
 
 -- | Perform an @X@ action. If it returns @Any True@, unwind the
@@ -444,7 +445,7 @@ setFocusX w = withWindowSet $ \ws -> do
 -- layout the windows, in which case changes are handled through a refresh.
 sendMessage :: Message a => a -> X ()
 sendMessage a = windowBracket_ $ do
-    w <- W.workspace . W.current <$> gets windowset
+    w <- gets $ W.workspace . W.current . windowset
     ml' <- handleMessage (W.layout w) (SomeMessage a) `catchX` return Nothing
     whenJust ml' $ \l' ->
         modifyWindowSet $ \ws -> ws { W.current = (W.current ws)
@@ -479,9 +480,9 @@ updateLayout i ml = whenJust ml $ \l ->
 -- | Set the layout of the currently viewed workspace.
 setLayout :: Layout Window -> X ()
 setLayout l = do
-    ss@(W.StackSet { W.current = c@(W.Screen { W.workspace = ws })}) <- gets windowset
+    ss@W.StackSet{ W.current = c@W.Screen{ W.workspace = ws }} <- gets windowset
     handleMessage (W.layout ws) (SomeMessage ReleaseResources)
-    windows $ const $ ss {W.current = c { W.workspace = ws { W.layout = l } } }
+    windows $ const $ ss{ W.current = c{ W.workspace = ws{ W.layout = l } } }
 
 ------------------------------------------------------------------------
 -- Utilities
@@ -607,8 +608,7 @@ floatLocation w =
       sc <- gets $ W.current . windowset
       return (W.screen sc, W.RationalRect 0 0 1 1)
 
-  where fi x = fromIntegral x
-        go = withDisplay $ \d -> do
+  where go = withDisplay $ \d -> do
           ws <- gets windowset
           wa <- io $ getWindowAttributes d w
           let bw = (fromIntegral . wa_border_width) wa
@@ -634,6 +634,9 @@ floatLocation w =
 
           return (W.screen sc, rr)
 
+        fi :: (Integral a, Num b) => a -> b
+        fi = fromIntegral
+
 -- | Given a point, determine the screen (if any) that contains it.
 pointScreen :: Position -> Position
             -> X (Maybe (W.Screen WorkspaceId (Layout Window) Window ScreenId ScreenDetail))
@@ -732,7 +735,7 @@ mkAdjust w = withDisplay $ \d -> liftIO $ do
     sh <- getWMNormalHints d w
     wa <- C.try $ getWindowAttributes d w
     case wa of
-         Left  err -> const (return id) (err :: C.SomeException)
+         Left (_ :: C.SomeException) -> return id
          Right wa' ->
             let bw = fromIntegral $ wa_border_width wa'
             in  return $ applySizeHints bw sh