diff --git a/core/CCKList.ml b/core/CCKList.ml
index 337310f4..05656a9c 100644
--- a/core/CCKList.ml
+++ b/core/CCKList.ml
@@ -25,31 +25,29 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 (** {1 Continuation List} *)
 
-
-type + 'a t =
+type + 'a t = unit -> 
   [ `Nil
-  | `Cons of 'a * (unit -> 'a t)
+  | `Cons of 'a * 'a t
   ]
 
-let nil = `Nil
-let _nil () = nil
-let cons a b = `Cons (a,b)
+let nil () = `Nil
+let cons a b () = `Cons (a,b)
 let empty = nil
 
-let singleton x = `Cons (x, fun () -> `Nil)
+let singleton x () = `Cons (x, nil)
 
-let is_empty = function
+let is_empty l = match l () with
   | `Nil -> true
   | `Cons _ -> false
 
 let to_list l =
-  let rec direct i (l:'a t) = match l with
+  let rec direct i (l:'a t) = match l () with
     | `Nil -> []
     | _ when i=0 -> safe [] l
-    | `Cons (x, f) -> x :: direct (i-1) (f ())
-  and safe acc l = match l with
+    | `Cons (x, f) -> x :: direct (i-1) f
+  and safe acc l = match l () with
     | `Nil -> List.rev acc
-    | `Cons (x,l') -> safe (x::acc) (l' ())
+    | `Cons (x,l') -> safe (x::acc) l'
   in
   direct 200 l
 
@@ -57,87 +55,104 @@ let of_list l =
   let rec aux l () = match l with
     | [] -> `Nil
     | x::l' -> `Cons (x, aux l')
-  in aux l ()
+  in aux l
 
 type 'a sequence = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 
-let rec to_seq res k = match res with
+let rec to_seq res k = match res () with
   | `Nil -> ()
-  | `Cons (s, f) -> k s; to_seq (f ()) k
+  | `Cons (s, f) -> k s; to_seq f k
 
 let to_gen l =
   let l = ref l in
   fun () ->
-    match !l with
+    match !l () with
     | `Nil -> None
     | `Cons (x,l') ->
-        l := l' ();
+        l := l';
         Some x
 
-let rec fold f acc res = match res with
+let rec fold f acc res = match res () with
   | `Nil -> acc
-  | `Cons (s, cont) -> fold f (f acc s) (cont ())
+  | `Cons (s, cont) -> fold f (f acc s) cont
 
-let rec iter f l = match l with
+let rec iter f l = match l () with
   | `Nil -> ()
-  | `Cons (x, l') -> f x; iter f (l' ())
+  | `Cons (x, l') -> f x; iter f l'
 
 let length l = fold (fun acc _ -> acc+1) 0 l
 
-let rec take n (l:'a t):'a t = match l with
+let rec take n (l:'a t) () = match l () with
   | _ when n=0 -> `Nil
   | `Nil -> `Nil
-  | `Cons (x,l') -> `Cons (x, fun () -> take (n-1) (l' ()))
+  | `Cons (x,l') -> `Cons (x, take (n-1) l')
 
-let rec drop n (l:'a t) = match l with
-  | _ when n=0 -> l
+let rec drop n (l:'a t) () = match l () with
+  | l' when n=0 -> l'
   | `Nil -> `Nil
-  | `Cons (_,l') -> drop (n-1) (l'())
+  | `Cons (_,l') -> drop (n-1) l' ()
 
-let rec map f l = match l with
+(*$Q
+  (Q.pair (Q.list Q.small_int) Q.small_int) (fun (l,n) -> \
+    let s = of_list l in let s1, s2 = take n s, drop n s in \
+    append s1 s2 |> to_list = l  )
+*)
+
+let rec map f l () = match l () with
   | `Nil -> `Nil
-  | `Cons (x, l') -> `Cons (f x, fun () -> map f (l' ()))
+  | `Cons (x, l') -> `Cons (f x, map f l')
 
-let rec fmap f (l:'a t):'b t = match l with
+(*$T
+  (map ((+) 1) (1 -- 5) |> to_list) = (2 -- 6 |> to_list)
+*)
+
+let rec fmap f (l:'a t) () = match l() with
   | `Nil -> `Nil
   | `Cons (x, l') ->
       begin match f x with
-      | None -> fmap f (l' ())
-      | Some y -> `Cons (y, fun () -> fmap f (l' ()))
+      | None -> fmap f l' ()
+      | Some y -> `Cons (y, fmap f l')
       end
 
-let rec filter p l = match l with
+(*$T
+  fmap (fun x -> if x mod 2=0 then Some (x*3) else None) (1--10) |> to_list \
+    = [6;12;18;24;30]
+*)
+
+let rec filter p l () = match l () with
   | `Nil -> `Nil
   | `Cons (x, l') ->
       if p x
-      then `Cons (x, fun () -> filter p (l' ()))
-      else filter p (l' ())
+      then `Cons (x, filter p l')
+      else filter p l' ()
 
-let rec append l1 l2 = match l1 with
-  | `Nil -> l2
-  | `Cons (x, l1') -> `Cons (x, fun () -> append (l1' ()) l2)
+let rec append l1 l2 () = match l1 () with
+  | `Nil -> l2 ()
+  | `Cons (x, l1') -> `Cons (x, append l1' l2)
 
-let rec flat_map f l = match l with
+let rec flat_map f l () = match l () with
   | `Nil -> `Nil
   | `Cons (x, l') ->
-      _flat_map_app f (f x) (l' ()) ()
-and _flat_map_app f l l' () = match l with
-  | `Nil -> flat_map f l'
+      _flat_map_app f (f x) l' ()
+and _flat_map_app f l l' () = match l () with
+  | `Nil -> flat_map f l' ()
   | `Cons (x, tl) ->
-      `Cons (x, _flat_map_app f (tl ()) l')
+      `Cons (x, _flat_map_app f tl l')
 
 let flatten l = flat_map (fun x->x) l
 
 let range i j =
   let rec aux i j () =
-    if i=j then cons i _nil
+    if i=j then `Cons(i, nil)
     else if i<j then `Cons (i, aux (i+1) j)
     else `Cons (i, aux (i-1) j)
-  in aux i j ()
+  in aux i j
 
 (*$T
   range 0 5 |> to_list = [0;1;2;3;4;5]
   range 0 0 |> to_list = [0]
   range 5 2 |> to_list = [5;4;3;2]
 *)
+
+let (--) = range
diff --git a/core/CCKList.mli b/core/CCKList.mli
index 0975a24c..ec3a8ec9 100644
--- a/core/CCKList.mli
+++ b/core/CCKList.mli
@@ -25,16 +25,16 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 (** {1 Continuation List} *)
 
-type + 'a t =
+type + 'a t = unit -> 
   [ `Nil
-  | `Cons of 'a * (unit -> 'a t)
+  | `Cons of 'a * 'a t
   ]
 
 val nil : 'a t
 
 val empty : 'a t
 
-val cons : 'a -> (unit -> 'a t) -> 'a t
+val cons : 'a -> 'a t -> 'a t
 
 val singleton : 'a -> 'a t
 
@@ -75,3 +75,5 @@ val flat_map : ('a -> 'b t) -> 'a t -> 'b t
 val flatten : 'a t t -> 'a t
 
 val range : int -> int -> int t
+
+val (--) : int -> int -> int t