Replace tail with drop 1

Where appropriate.

XMonad/Actions/EasyMotion.hs

@@ -387,5 +387,5 @@ handleKeyboard dpy drawFn cancel selected deselected = do
       _   -> handleKeyboard dpy drawFn cancel (trim fg) (clear bg) >>= retryBackspace
    where
     (fg, bg) = partition ((== Just keySym) . listToMaybe . chord) selected
-    trim = map (\o -> o { chord = tail $ chord o })
+    trim = map (\o -> o { chord = drop 1 $ chord o })
     clear = map (\o -> o { chord = [] })

XMonad/Actions/Navigation2D.hs

@@ -783,8 +783,7 @@ doCenterNavigation dir (cur, rect) winrects
 
     -- All the points that coincide with the current center and succeed it
     -- in the (appropriately ordered) window stack.
-    onCtr' = L.tail $ L.dropWhile ((cur /=) . fst) onCtr
+    onCtr' = L.drop 1 $ L.dropWhile ((cur /=) . fst) onCtr
-             -- tail should be safe here because cur should be in onCtr
 
     -- All the points that do not coincide with the current center and which
     -- lie in the (rotated) right cone.
@@ -885,7 +884,7 @@ swap win winset = W.focusWindow cur
     newvisws  = zipWith (\ws wns -> ws { W.stack = W.differentiate wns }) visws newwins
     newscrs   = zipWith (\scr ws -> scr { W.workspace = ws }) scrs newvisws
     newwinset = winset { W.current = head newscrs
-                       , W.visible = tail newscrs
+                       , W.visible = drop 1 newscrs
                        }
 
 -- | Calculates the center of a rectangle

XMonad/Actions/Search.hs

@@ -322,7 +322,7 @@ searchEngine name site = searchEngineF name (\s -> site ++ escape s)
    inside of a URL instead of in the end) you can use the alternative 'searchEngineF' function.
 
 > searchFunc :: String -> String
-> searchFunc s | "wiki:"    `isPrefixOf` s = "https://en.wikipedia.org/wiki/" ++ (escape $ tail $ snd $ break (==':') s)
+> searchFunc s | "wiki:"    `isPrefixOf` s = "https://en.wikipedia.org/wiki/" ++ (escape $ drop 1 $ snd $ break (==':') s)
 >              | "https://" `isPrefixOf` s = s
 >              | otherwise                 = (use google) s
 > myNewEngine = searchEngineF "mymulti" searchFunc

XMonad/Actions/WorkspaceCursors.hs

@@ -98,7 +98,7 @@ makeCursors ::  [[String]] -> Cursors String
 makeCursors [] = error "Workspace Cursors cannot be empty"
 makeCursors a = concat . reverse <$> foldl addDim x xs
     where x = end $ map return $ head a
-          xs = map (map return) $ tail a
+          xs = map (map return) $ drop 1 a
           -- this could probably be simplified, but this true:
           -- toList . makeCursors == map (concat . reverse) . sequence . reverse . map (map (:[]))
           -- the strange order is used because it makes the regular M-1..9

XMonad/Hooks/DebugEvents.hs

@@ -687,9 +687,7 @@ dumpString =  do
                                             \s -> if null s
                                                   then Nothing
                                                   else let (w,s'') = break (== '\NUL') s
-                                                           s'      = if null s''
+                                                           s'      = drop 1 s''
-                                                                     then s''
-                                                                     else tail s''
                                                         in Just (w,s')
                                    case ss of
                                      [s] -> append $ show s

XMonad/Hooks/InsertPosition.hs

@@ -83,4 +83,4 @@ insertDown w = W.swapDown . W.insertUp w
 
 focusLast' ::  W.Stack a -> W.Stack a
 focusLast' st = let ws = W.integrate st
-    in W.Stack (last ws) (tail $ reverse ws) []
+    in W.Stack (last ws) (drop 1 $ reverse ws) []

XMonad/Hooks/StatusBar/PP.hs

@@ -464,7 +464,7 @@ xmobarStrip = converge (xmobarStripTags ["fc","icon","action"])
 
 converge :: (Eq a) => (a -> a) -> a -> a
 converge f a = let xs = iterate f a
-    in fst $ head $ dropWhile (uncurry (/=)) $ zip xs $ tail xs
+    in fst $ head $ dropWhile (uncurry (/=)) $ zip xs $ drop 1 xs
 
 xmobarStripTags :: [String] -- ^ tags
         -> String -> String -- ^ with all \<tag\>...\</tag\> removed

XMonad/Layout/CenteredMaster.hs

@@ -84,7 +84,7 @@ applyPosition pos wksp rect = do
      runLayout wksp rect
      else do
        let firstW = head ws
-       let other  = tail ws
+       let other  = drop 1 ws
        let filtStack = stack >>= W.filter (firstW /=)
        wrs <- runLayout (wksp {W.stack = filtStack}) rect
        return $ first ((firstW, place pos other rect) :) wrs

XMonad/Layout/Combo.hs

@@ -132,7 +132,7 @@ instance (LayoutClass l (), LayoutClass l1 a, LayoutClass l2 a, Read a, Show a,
 differentiate :: Eq q => [q] -> [q] -> Maybe (Stack q)
 differentiate (z:zs) xs | z `elem` xs = Just $ Stack { focus=z
                                                      , up = reverse $ takeWhile (/=z) xs
-                                                     , down = tail $ dropWhile (/=z) xs }
+                                                     , down = drop 1 $ dropWhile (/=z) xs }
                         | otherwise = differentiate zs xs
 differentiate [] xs = W.differentiate xs
 

XMonad/Layout/Dwindle.hs

@@ -159,8 +159,8 @@ squeeze dir ratio rect st = zip wins rects
         nwins   = length wins
         sizes   = take nwins $ unfoldr (\r -> Just (r * ratio, r * ratio)) 1
         totals' = 0 : zipWith (+) sizes totals'
-        totals  = tail totals'
+        totals  = drop 1 totals'
-        splits  = zip (tail sizes) totals
+        splits  = zip (drop 1 sizes) totals
         ratios  = reverse $ map (uncurry (/)) splits
         rects   = genRects rect ratios
         genRects r []     = [r]

XMonad/Layout/Grid.hs

@@ -61,7 +61,7 @@ arrange aspectRatio (Rectangle rx ry rw rh) st = zip st rectangles
     mincs = max 1 $ nwins `div` ncols
     extrs = nwins - ncols * mincs
     chop :: Int -> Dimension -> [(Position, Dimension)]
-    chop n m = ((0, m - k * fromIntegral (pred n)) :) . map (, k) . tail . reverse . take n . tail . iterate (subtract k') $ m'
+    chop n m = ((0, m - k * fromIntegral (pred n)) :) . map (, k) . drop 1 . reverse . take n . drop 1 . iterate (subtract k') $ m'
         where
         k :: Dimension
         k = m `div` fromIntegral n

XMonad/Layout/Groups/Helpers.hs

@@ -155,7 +155,7 @@ focusHelper :: (Bool -> Bool) -- ^ if you want to focus a floating window, 'id'.
             -> X ()
 focusHelper f g = withFocused $ \w -> do
                  ws <- getWindows
-                 let (before, tail -> after) = span (/=w) ws
+                 let (before, drop 1 -> after) = span (/=w) ws
                  let toFocus = g $ after ++ before
                  floats <- getFloats
                  case filter (f . flip elem floats) toFocus of

XMonad/Layout/MultiColumns.hs

@@ -96,7 +96,7 @@ instance LayoutClass MultiCol a where
                       ,fmap incmastern (fromMessage m)]
             where resize Shrink = l { multiColSize = max (-0.5) $ s-ds }
                   resize Expand = l { multiColSize = min 1 $ s+ds }
-                  incmastern (IncMasterN x) = l { multiColNWin = take a n ++ [newval] ++ tail r }
+                  incmastern (IncMasterN x) = l { multiColNWin = take a n ++ [newval] ++ drop 1 r }
                       where newval =  max 0 $ head r + x
                             r = drop a n
                   n = multiColNWin l

XMonad/Layout/OneBig.hs

@@ -66,7 +66,7 @@ oneBigLayout (OneBig cx cy) rect stack = [(master,masterRect)]
             w = wd rect
             m = calcBottomWs n w h'
             master = head ws
-            other  = tail ws
+            other  = drop 1 ws
             bottomWs = take m other
             rightWs = drop m other
             masterRect = cmaster n m cx cy rect

XMonad/Layout/Spiral.hs

@@ -45,7 +45,7 @@ import XMonad.StackSet ( integrate )
 -- "XMonad.Doc.Extending#Editing_the_layout_hook".
 
 fibs :: [Integer]
-fibs = 1 : 1 : zipWith (+) fibs (tail fibs)
+fibs = 1 : 1 : zipWith (+) fibs (drop 1 fibs)
 
 mkRatios :: [Integer] -> [Rational]
 mkRatios (x1:x2:xs) = (x1 % x2) : mkRatios (x2:xs)
@@ -82,7 +82,7 @@ data SpiralWithDir a = SpiralWithDir Direction Rotation Rational
 instance LayoutClass SpiralWithDir a where
     pureLayout (SpiralWithDir dir rot scale) sc stack = zip ws rects
         where ws = integrate stack
-              ratios = blend scale . reverse . take (length ws - 1) . mkRatios $ tail fibs
+              ratios = blend scale . reverse . take (length ws - 1) . mkRatios $ drop 1 fibs
               rects = divideRects (zip ratios dirs) sc
               dirs  = dropWhile (/= dir) $ case rot of
                                            CW  -> cycle [East .. North]

XMonad/Prompt.hs

@@ -540,7 +540,7 @@ mkXPromptWithModes modes conf = do
   let defaultMode = head modes
       modeStack = W.Stack { W.focus = defaultMode -- Current mode
                           , W.up = []
-                          , W.down = tail modes -- Other modes
+                          , W.down = drop 1 modes -- Other modes
                           }
       om = XPMultipleModes modeStack
   st' <- mkXPromptImplementation (showXPrompt defaultMode) conf { alwaysHighlight = True } om
@@ -650,7 +650,7 @@ eventLoop handle stopAction = do
                                 return (ks, s, ev)
                         else return (noSymbol, "", ev)
         l   -> do
-                modify $ \s -> s { eventBuffer = tail l }
+                modify $ \s -> s { eventBuffer = drop 1 l }
                 return $ head l
     handle (keysym,keystr) event
     stopAction >>= \stop -> unless stop (eventLoop handle stopAction)
@@ -1315,7 +1315,7 @@ deleteString d =
         c oc oo
             | oo >= length oc && d == Prev = take (oo - 1) oc
             | oo <  length oc && d == Prev = take (oo - 1) f ++ ss
-            | oo <  length oc && d == Next = f ++ tail ss
+            | oo <  length oc && d == Next = f ++ drop 1 ss
             | otherwise = oc
             where (f,ss) = splitAt oo oc
 
@@ -1523,7 +1523,7 @@ printPrompt drw = do
       (preCursor, cursor, postCursor) = if offset >= length com
                  then (str, " ","") -- add a space: it will be our cursor ;-)
                  else let (a, b) = splitAt offset com
-                      in (prt ++ a, [head b], tail b)
+                      in (prt ++ a, take 1 b, drop 1 b)
 
   -- vertical and horizontal text alignment
   (asc, desc) <- io $ textExtentsXMF fontS str  -- font ascent and descent
@@ -1780,7 +1780,7 @@ breakAtSpace s
     | " \\" `isPrefixOf` s2 = (s1 ++ " " ++ s1', s2')
     | otherwise = (s1, s2)
       where (s1, s2 ) = break isSpace s
-            (s1',s2') = breakAtSpace $ tail s2
+            (s1',s2') = breakAtSpace $ drop 1 s2
 
 -- | 'historyCompletion' provides a canned completion function much like
 --   'getShellCompl'; you pass it to mkXPrompt, and it will make completions work

XMonad/Util/DebugWindow.hs

@@ -57,9 +57,7 @@ debugWindow w =  do
                              \s -> if null s
                                      then Nothing
                                      else let (w'',s'') = break (== '\NUL') s
-                                              s'      = if null s''
+                                              s'        = drop 1 s''
-                                                          then s''
-                                                          else tail s''
                                           in Just (w'',s')
       t <- catchX' (wrap <$> getEWMHTitle  "VISIBLE" w) $
            catchX' (wrap <$> getEWMHTitle  ""        w) $
@@ -202,7 +200,7 @@ windowType d w ts =  do
                                       Just s'' -> s''
                                       _        -> '<':show a ++ ">"
                             unAtoms as (t ++ (if i then ' ':s else s)) True
-    
+
     simplify       :: String -> Atom -> X String
     simplify pfx a =  do
                         s' <- io $ getAtomName d a
@@ -214,10 +212,10 @@ windowType d w ts =  do
                                        return s
 
     -- note that above it says this checks all of them before simplifying.
-    -- I'll do that after I'm confident this works as intended.    
+    -- I'll do that after I'm confident this works as intended.
     windowState     :: [Atom] -> X String
     windowState []  =  return ""
     windowState as' =  go as' ";"
       where
         go []     t = return t
-        go (a:as) t = simplify "_NET_WM_STATE_" a >>= \t' -> go as (t ++ ' ':t') 
+        go (a:as) t = simplify "_NET_WM_STATE_" a >>= \t' -> go as (t ++ ' ':t')

XMonad/Util/EZConfig.hs

@@ -439,7 +439,7 @@ mkSubmaps' subm binds = map combine gathered
                  $ binds
         combine [([k],act)] = (k,act)
         combine ks = (head . fst . head $ ks,
-                      subm . mkSubmaps' subm $ map (first tail) ks)
+                      subm . mkSubmaps' subm $ map (first (drop 1)) ks)
         fstKey = (==) `on` (head . fst)
 
 -- | Given a configuration record and a list of (key sequence

XMonad/Util/Stack.hs

@@ -162,20 +162,20 @@ focusUpZ :: Zipper a -> Zipper a
 focusUpZ Nothing = Nothing
 focusUpZ (Just s) | u:up <- W.up s = Just $ W.Stack u up (W.focus s:W.down s)
 focusUpZ (Just s) | null $ W.down s = Just s
-focusUpZ (Just (W.Stack f _ down)) = Just $ W.Stack (last down) (tail (reverse down) ++ [f]) []
+focusUpZ (Just (W.Stack f _ down)) = Just $ W.Stack (last down) (drop 1 (reverse down) ++ [f]) []
 
 -- | Move the focus to the next element
 focusDownZ :: Zipper a -> Zipper a
 focusDownZ Nothing = Nothing
 focusDownZ (Just s) | d:down <- W.down s = Just $ W.Stack d (W.focus s:W.up s) down
 focusDownZ (Just s) | null $ W.up s = Just s
-focusDownZ (Just (W.Stack f up _)) = Just $ W.Stack (last up) [] (tail (reverse up) ++ [f])
+focusDownZ (Just (W.Stack f up _)) = Just $ W.Stack (last up) [] (drop 1 (reverse up) ++ [f])
 
 -- | Move the focus to the first element
 focusMasterZ :: Zipper a -> Zipper a
 focusMasterZ Nothing = Nothing
 focusMasterZ (Just (W.Stack f up down)) | not $ null up
-    = Just $ W.Stack (last up) [] (tail (reverse up) ++ [f] ++ down)
+    = Just $ W.Stack (last up) [] (drop 1 (reverse up) ++ [f] ++ down)
 focusMasterZ (Just s) = Just s
 
 -- | Refocus a @Stack a@ on an element satisfying the predicate, or fail to

tests/Selective.hs

@@ -34,14 +34,14 @@ prop_select_focus sel (stk :: Stack Int) = focus stk == focus (select sel' stk)
 prop_select_increasing :: Selection l -> Stack Int -> Bool
 prop_select_increasing sel (stk :: Stack Int) =
     let res = integrate $ select sel stk
-     in and . zipWith (<) res $ tail res
+     in and . zipWith (<) res $ drop 1 res
 
 -- selection has the form [0..l] ++ [m..n]
 -- relies on the Arbitrary instance for Stack Int generating stacks like [0..k]
 prop_select_two_consec :: Selection l -> Stack Int -> Bool
 prop_select_two_consec sel (stk :: Stack Int) =
     let wins = integrate $ select sel stk
-     in (length . filter not . zipWith ((==) . (+1)) wins $ tail wins) <= 1
+     in (length . filter not . zipWith ((==) . (+1)) wins $ drop 1 wins) <= 1
 
 -- update preserves invariants on selections
 prop_update_nm :: Selection l -> Stack Int -> Bool