Merge pull request #872 from Bodigrim/avoid-head-and-tail

Avoid `Data.List.{head,tail}`

Author: treeowl

containers/src/Data/IntMap/Internal.hs

@@ -3504,7 +3504,7 @@ showsBars :: [String] -> ShowS
 showsBars bars
   = case bars of
       [] -> id
-      _  -> showString (concat (reverse (tail bars))) . showString node
+      _ : tl -> showString (concat (reverse tl)) . showString node
 
 node :: String
 node = "+--"

containers/src/Data/IntSet/Internal.hs

@@ -1299,7 +1299,7 @@ showWide wide bars
 
 showsBars :: [String] -> ShowS
 showsBars [] = id
-showsBars bars = showString (concat (reverse (tail bars))) . showString node
+showsBars (_ : tl) = showString (concat (reverse tl)) . showString node
 
 showsBitMap :: Word -> ShowS
 showsBitMap = showString . showBitMap

containers/src/Data/Map/Internal/Debug.hs

@@ -91,7 +91,7 @@ showsBars :: [String] -> ShowS
 showsBars bars
   = case bars of
       [] -> id
-      _  -> showString (concat (reverse (tail bars))) . showString node
+      _ : tl -> showString (concat (reverse tl)) . showString node
 
 node :: String
 node           = "+--"

containers/src/Data/Set/Internal.hs

@@ -1977,7 +1977,7 @@ showsBars :: [String] -> ShowS
 showsBars bars
   = case bars of
       [] -> id
-      _  -> showString (concat (reverse (tail bars))) . showString node
+      _ : tl -> showString (concat (reverse tl)) . showString node
 
 node :: String
 node           = "+--"