simplify insertion code (#104)

* simplify insertion code

* restore use of `comp`

avoid instance lookup overhead

Author: matthewleon

src/Data/Map.purs

@@ -274,37 +274,37 @@ data KickUp k v = KickUp (Map k v) k v (Map k v)
 
 -- | Insert or replace a key/value pair in a map
 insert :: forall k v. Ord k => k -> v -> Map k v -> Map k v
-insert = down Nil
+insert k v = down Nil
   where
   comp :: k -> k -> Ordering
   comp = compare
 
-  down :: List (TreeContext k v) -> k -> v -> Map k v -> Map k v
-  down ctx k v Leaf = up ctx (KickUp Leaf k v Leaf)
-  down ctx k v (Two left k1 v1 right) =
+  down :: List (TreeContext k v) -> Map k v -> Map k v
+  down ctx Leaf = up ctx (KickUp Leaf k v Leaf)
+  down ctx (Two left k1 v1 right) =
     case comp k k1 of
       EQ -> fromZipper ctx (Two left k v right)
-      LT -> down (Cons (TwoLeft k1 v1 right) ctx) k v left
-      _  -> down (Cons (TwoRight left k1 v1) ctx) k v right
-  down ctx k v (Three left k1 v1 mid k2 v2 right) =
+      LT -> down (Cons (TwoLeft k1 v1 right) ctx) left
+      _  -> down (Cons (TwoRight left k1 v1) ctx) right
+  down ctx (Three left k1 v1 mid k2 v2 right) =
     case comp k k1 of
       EQ -> fromZipper ctx (Three left k v mid k2 v2 right)
       c1 ->
         case c1, comp k k2 of
           _ , EQ -> fromZipper ctx (Three left k1 v1 mid k v right)
-          LT, _  -> down (Cons (ThreeLeft k1 v1 mid k2 v2 right) ctx) k v left
-          GT, LT -> down (Cons (ThreeMiddle left k1 v1 k2 v2 right) ctx) k v mid
-          _ , _  -> down (Cons (ThreeRight left k1 v1 mid k2 v2) ctx) k v right
+          LT, _  -> down (Cons (ThreeLeft k1 v1 mid k2 v2 right) ctx) left
+          GT, LT -> down (Cons (ThreeMiddle left k1 v1 k2 v2 right) ctx) mid
+          _ , _  -> down (Cons (ThreeRight left k1 v1 mid k2 v2) ctx) right
 
   up :: List (TreeContext k v) -> KickUp k v -> Map k v
-  up Nil (KickUp left k v right) = Two left k v right
+  up Nil (KickUp left k' v' right) = Two left k' v' right
   up (Cons x ctx) kup =
     case x, kup of
-      TwoLeft k1 v1 right, KickUp left k v mid -> fromZipper ctx (Three left k v mid k1 v1 right)
-      TwoRight left k1 v1, KickUp mid k v right -> fromZipper ctx (Three left k1 v1 mid k v right)
-      ThreeLeft k1 v1 c k2 v2 d, KickUp a k v b -> up ctx (KickUp (Two a k v b) k1 v1 (Two c k2 v2 d))
-      ThreeMiddle a k1 v1 k2 v2 d, KickUp b k v c -> up ctx (KickUp (Two a k1 v1 b) k v (Two c k2 v2 d))
-      ThreeRight a k1 v1 b k2 v2, KickUp c k v d -> up ctx (KickUp (Two a k1 v1 b) k2 v2 (Two c k v d))
+      TwoLeft k1 v1 right, KickUp left k' v' mid -> fromZipper ctx (Three left k' v' mid k1 v1 right)
+      TwoRight left k1 v1, KickUp mid k' v' right -> fromZipper ctx (Three left k1 v1 mid k' v' right)
+      ThreeLeft k1 v1 c k2 v2 d, KickUp a k' v' b -> up ctx (KickUp (Two a k' v' b) k1 v1 (Two c k2 v2 d))
+      ThreeMiddle a k1 v1 k2 v2 d, KickUp b k' v' c -> up ctx (KickUp (Two a k1 v1 b) k' v' (Two c k2 v2 d))
+      ThreeRight a k1 v1 b k2 v2, KickUp c k' v' d -> up ctx (KickUp (Two a k1 v1 b) k2 v2 (Two c k' v' d))
 
 -- | Delete a key and its corresponding value from a map.
 delete :: forall k v. Ord k => k -> Map k v -> Map k v