Various clean-ups suggested by HLint

XMonad/Config.hs

@@ -220,15 +220,15 @@ keys conf@(XConfig {XMonad.modMask = modMask}) = M.fromList $
 -- | Mouse bindings: default actions bound to mouse events
 --
 mouseBindings :: XConfig Layout -> M.Map (KeyMask, Button) (Window -> X ())
-mouseBindings (XConfig {XMonad.modMask = modMask}) = M.fromList $
+mouseBindings (XConfig {XMonad.modMask = modMask}) = M.fromList
     -- mod-button1 %! Set the window to floating mode and move by dragging
-    [ ((modMask, button1), (\w -> focus w >> mouseMoveWindow w
-                                          >> windows W.shiftMaster))
+    [ ((modMask, button1), \w -> focus w >> mouseMoveWindow w
+                                          >> windows W.shiftMaster)
     -- mod-button2 %! Raise the window to the top of the stack
-    , ((modMask, button2), (\w -> focus w >> windows W.shiftMaster))
+    , ((modMask, button2), \w -> focus w >> windows W.shiftMaster)
     -- mod-button3 %! Set the window to floating mode and resize by dragging
-    , ((modMask, button3), (\w -> focus w >> mouseResizeWindow w
-                                          >> windows W.shiftMaster))
+    , ((modMask, button3), \w -> focus w >> mouseResizeWindow w
+                                         >> windows W.shiftMaster)
     -- you may also bind events to the mouse scroll wheel (button4 and button5)
     ]
 

XMonad/Core.hs

@@ -456,7 +456,7 @@ recompile force = io $ do
       then do
         -- temporarily disable SIGCHLD ignoring:
         uninstallSignalHandlers
-        status <- bracket (openFile err WriteMode) hClose $ \h -> do
+        status <- bracket (openFile err WriteMode) hClose $ \h ->
             waitForProcess =<< runProcess "ghc" ["--make", "xmonad.hs", "-i", "-ilib", "-fforce-recomp", "-v0", "-o",binn] (Just dir)
                                     Nothing Nothing Nothing (Just h)
 

XMonad/Layout.hs

@@ -125,7 +125,7 @@ instance LayoutClass l a => LayoutClass (Mirror l) a where
 
 -- | Mirror a rectangle.
 mirrorRect :: Rectangle -> Rectangle
-mirrorRect (Rectangle rx ry rw rh) = (Rectangle ry rx rh rw)
+mirrorRect (Rectangle rx ry rw rh) = Rectangle ry rx rh rw
 
 ------------------------------------------------------------------------
 -- LayoutClass selection manager
@@ -173,7 +173,7 @@ choose (Choose d l r) d' ml      mr = f lr
 
 instance (LayoutClass l a, LayoutClass r a) => LayoutClass (Choose l r) a where
     runLayout (W.Workspace i (Choose L l r) ms) =
-        fmap (second . fmap $ flip (Choose L) $ r) . runLayout (W.Workspace i l ms)
+        fmap (second . fmap $ flip (Choose L) r) . runLayout (W.Workspace i l ms)
     runLayout (W.Workspace i (Choose R l r) ms) =
         fmap (second . fmap $ Choose R l) . runLayout (W.Workspace i r ms)
 
@@ -194,7 +194,7 @@ instance (LayoutClass l a, LayoutClass r a) => LayoutClass (Choose l r) a where
 
             R -> choose c R Nothing =<< handle r NextNoWrap
 
-    handleMessage c@(Choose _ l _) m | Just FirstLayout <- fromMessage m = do        
+    handleMessage c@(Choose _ l _) m | Just FirstLayout <- fromMessage m =
         flip (choose c L) Nothing =<< handle l FirstLayout
 
     handleMessage c@(Choose d l r) m | Just ReleaseResources <- fromMessage m =

XMonad/Operations.hs

@@ -210,7 +210,7 @@ clientMask = structureNotifyMask .|. enterWindowMask .|. propertyChangeMask
 setInitialProperties :: Window -> X ()
 setInitialProperties w = asks normalBorder >>= \nb -> withDisplay $ \d -> do
     setWMState w iconicState
-    io $ selectInput d w $ clientMask
+    io $ selectInput d w clientMask
     bw <- asks (borderWidth . config)
     io $ setWindowBorderWidth d w bw
     -- we must initially set the color of new windows, to maintain invariants
@@ -320,14 +320,13 @@ setFocusX w = withWindowSet $ \ws -> do
     dpy <- asks display
 
     -- clear mouse button grab and border on other windows
-    forM_ (W.current ws : W.visible ws) $ \wk -> do
-        forM_ (W.index (W.view (W.tag (W.workspace wk)) ws)) $ \otherw -> do
+    forM_ (W.current ws : W.visible ws) $ \wk ->
+        forM_ (W.index (W.view (W.tag (W.workspace wk)) ws)) $ \otherw ->
             setButtonGrab True otherw
 
     -- If we ungrab buttons on the root window, we lose our mouse bindings.
     whenX (not <$> isRoot w) $ setButtonGrab False w
-    io $ do setInputFocus dpy w revertToPointerRoot 0
-            -- raiseWindow dpy w
+    io $ setInputFocus dpy w revertToPointerRoot 0
 
 ------------------------------------------------------------------------
 -- Message handling
@@ -338,7 +337,7 @@ sendMessage :: Message a => a -> X ()
 sendMessage a = do
     w <- W.workspace . W.current <$> gets windowset
     ml' <- handleMessage (W.layout w) (SomeMessage a) `catchX` return Nothing
-    whenJust ml' $ \l' -> do
+    whenJust ml' $ \l' ->
         windows $ \ws -> ws { W.current = (W.current ws)
                                 { W.workspace = (W.workspace $ W.current ws)
                                   { W.layout = l' }}}
@@ -438,7 +437,7 @@ floatLocation w = withDisplay $ \d -> do
                             (fi (wa_width  wa + bw*2) % fi (rect_width sr))
                             (fi (wa_height wa + bw*2) % fi (rect_height sr))
 
-    return (W.screen $ sc, rr)
+    return (W.screen sc, rr)
   where fi x = fromIntegral x
 
 -- | Given a point, determine the screen (if any) that contains it.
@@ -508,7 +507,7 @@ mouseResizeWindow w = whenX (isClient w) $ withDisplay $ \d -> do
     wa <- io $ getWindowAttributes d w
     sh <- io $ getWMNormalHints d w
     io $ warpPointer d none w 0 0 0 0 (fromIntegral (wa_width wa)) (fromIntegral (wa_height wa))
-    mouseDrag (\ex ey -> do
+    mouseDrag (\ex ey ->
                  io $ resizeWindow d w `uncurry`
                     applySizeHintsContents sh (ex - fromIntegral (wa_x wa),
                                                ey - fromIntegral (wa_y wa)))

XMonad/StackSet.hs

@@ -52,7 +52,7 @@ module XMonad.StackSet (
     ) where
 
 import Prelude hiding (filter)
-import Data.Maybe   (listToMaybe,isJust)
+import Data.Maybe   (listToMaybe,isJust,fromMaybe)
 import qualified Data.List as L (deleteBy,find,splitAt,filter,nub)
 import Data.List ( (\\) )
 import qualified Data.Map  as M (Map,insert,delete,empty)
@@ -369,7 +369,7 @@ reverseStack (Stack t ls rs) = Stack t rs ls
 --
 focusWindow :: (Eq s, Eq a, Eq i) => a -> StackSet i l a s sd -> StackSet i l a s sd
 focusWindow w s | Just w == peek s = s
-                | otherwise        = maybe s id $ do
+                | otherwise        = fromMaybe s $ do
                     n <- findTag w s
                     return $ until ((Just w ==) . peek) focusUp (view n s)