Add cps version of append

src/cps/cartesian.ml

@@ -15,10 +15,16 @@ let rec mapk f l k =
   | h :: tl -> mapk f tl (fun s -> k (f h :: s))
 ;;
 
+let rec appendk l1 l2 k =
+  match l1 with
+  | [] -> k l2
+  | h :: tl -> appendk tl l2 (fun s -> k (h :: s))
+;;
+
 let rec concatk xs k =
   match xs with
   | [] -> k []
-  | h :: tl -> concatk tl (fun s -> k (h @ s))
+  | h :: tl -> concatk tl (fun s1 -> appendk h s1 (fun s2 -> k s2))
 ;;
 
 let cartesiank l1 l2 k =

src/cps/monad_list.ml

@@ -33,13 +33,20 @@ module ListCPS = struct
     | h :: tl -> mapk f tl (fun s -> k (f h :: s))
   ;;
 
+  let rec appendk l1 l2 k =
+    match l1 with
+    | [] -> k l2
+    | h :: tl -> appendk tl l2 (fun s -> k (h :: s))
+  ;;
+
   let rec concatk xs k =
     match xs with
     | [] -> k []
-    | h :: tl -> concatk tl (fun s -> k (h @ s))
+    | h :: tl -> concatk tl (fun s1 -> appendk h s1 (fun s2 -> k s2))
   ;;
 
-  let bindk m f k = mapk f m (fun s -> concatk s k)
+  let bindk m f k = mapk f m (fun s1 -> concatk s1 (fun s2 -> k s2))
+  let bind m f = bindk m f (fun x -> x)
   let fail _ = []
 end