diff --git a/_oasis b/_oasis
index 67bc4326..5f8052bd 100644
--- a/_oasis
+++ b/_oasis
@@ -40,7 +40,8 @@ Library "containers"
   Path:             core
   Modules:          CCVector, CCDeque, CCGen, CCSequence, CCFQueue, CCMultiMap,
                     CCMultiSet, CCBV, CCPrint, CCPersistentHashtbl,
-                    CCLeftistheap, CCList, CCOpt, CCPair, CCFun
+                    CCLeftistheap, CCList, CCOpt, CCPair, CCFun, CCHash,
+                    CCKList
   FindlibName:      containers
 
 Library "containers_string"
diff --git a/core/CCHash.ml b/core/CCHash.ml
new file mode 100644
index 00000000..af0b9a3b
--- /dev/null
+++ b/core/CCHash.ml
@@ -0,0 +1,76 @@
+(*
+Copyright (c) 2013, Simon Cruanes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.  Redistributions in binary
+form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with
+the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*)
+
+(** {1 Hash combinators} *)
+
+type t = int
+type 'a hash_fun = 'a -> t
+
+let combine hash i =
+  (hash * 65599 + i) land max_int
+
+let (<<>>) = combine
+
+let hash_int i = combine 0 i
+
+let hash_int2 i j = combine i j
+
+let hash_int3 i j k = combine (combine i j) k
+
+let hash_int4 i j k l =
+  combine (combine (combine i j) k) l
+
+let rec hash_list f h l = match l with
+  | [] -> h
+  | x::l' -> hash_list f (combine h (f x)) l'
+
+let hash_array f h a =
+  let h = ref h in
+  Array.iter (fun x -> h := combine !h (f x)) a;
+  !h
+
+let hash_string s = Hashtbl.hash s
+
+let hash_pair h1 h2 (x,y) = combine (h1 x) (h2 y)
+let hash_triple h1 h2 h3 (x,y,z) = (h1 x) <<>> (h2 y) <<>> (h3 z)
+
+type 'a sequence = ('a -> unit) -> unit
+type 'a gen = unit -> 'a option
+type 'a klist = [`Nil | `Cons of 'a * (unit -> 'a klist)]
+
+let hash_seq f h seq =
+  let h = ref h in
+  seq (fun x -> h := !h <<>> f x);
+  !h
+
+let rec hash_gen f h g = match g () with
+  | None -> h
+  | Some x ->
+      hash_gen f (h <<>> f x) g
+
+let rec hash_klist f h l = match l with
+  | `Nil -> h
+  | `Cons (x,l') -> hash_klist f (h <<>> f x) (l' ())
+
diff --git a/core/CCHash.mli b/core/CCHash.mli
new file mode 100644
index 00000000..2233e240
--- /dev/null
+++ b/core/CCHash.mli
@@ -0,0 +1,64 @@
+(*
+Copyright (c) 2013, Simon Cruanes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.  Redistributions in binary
+form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with
+the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*)
+
+(** {1 Hash combinators}
+
+Combination of hashes based on the
+SDBM simple hash (see for instance
+{{:http://www.cse.yorku.ca/~oz/hash.html} this page})
+*)
+
+type t = int
+
+type 'a hash_fun = 'a -> t
+
+val combine : t -> t -> t
+  (** Combine two hashes. Non-commutative. *)
+
+val (<<>>) : t -> t -> t
+  (** Infix version of {!combine} *)
+
+val hash_int : int -> t
+val hash_int2 : int -> int -> t
+val hash_int3 : int -> int -> int -> t
+val hash_int4 : int -> int -> int -> int -> t
+
+val hash_string : string -> t
+
+val hash_list : 'a hash_fun -> t -> 'a list hash_fun
+(** Hash a list. Each element is hashed using [f]. *)
+
+val hash_array : 'a hash_fun -> t -> 'a array hash_fun
+
+val hash_pair : 'a hash_fun -> 'b hash_fun -> ('a * 'b) hash_fun
+val hash_triple : 'a hash_fun -> 'b hash_fun -> 'c hash_fun -> ('a * 'b * 'c) hash_fun
+
+type 'a sequence = ('a -> unit) -> unit
+type 'a gen = unit -> 'a option
+type 'a klist = [`Nil | `Cons of 'a * (unit -> 'a klist)]
+
+val hash_seq : 'a hash_fun -> t -> 'a sequence hash_fun
+val hash_gen : 'a hash_fun -> t -> 'a gen hash_fun
+val hash_klist : 'a hash_fun -> t -> 'a klist hash_fun
diff --git a/core/CCKList.ml b/core/CCKList.ml
new file mode 100644
index 00000000..72a9d60c
--- /dev/null
+++ b/core/CCKList.ml
@@ -0,0 +1,106 @@
+(*
+Copyright (c) 2013, Simon Cruanes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.  Redistributions in binary
+form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with
+the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*)
+
+(** {1 Continuation List} *)
+
+
+type + 'a t =
+  [ `Nil
+  | `Cons of 'a * (unit -> 'a t)
+  ]
+
+let nil = `Nil
+let cons a b = `Cons (a,b)
+
+let to_list l =
+  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
+    | `Nil -> List.rev acc
+    | `Cons (x,l') -> safe (x::acc) (l' ())
+  in
+  direct 200 l
+
+type 'a sequence = ('a -> unit) -> unit
+type 'a gen = unit -> 'a option
+
+let rec to_seq res k = match res with
+  | `Nil -> ()
+  | `Cons (s, f) -> k s; to_seq (f ()) k
+
+let to_gen l =
+  let l = ref l in
+  fun () ->
+    match !l with
+    | `Nil -> None
+    | `Cons (x,l') ->
+        l := l' ();
+        Some x
+
+let rec fold f acc res = match res with
+  | `Nil -> acc
+  | `Cons (s, cont) -> fold f (f acc s) (cont ())
+
+let length l = fold (fun acc _ -> acc+1) 0 l
+
+let rec take n (l:'a t):'a t = match l with
+  | _ when n=0 -> `Nil
+  | `Nil -> `Nil
+  | `Cons (x,l') -> `Cons (x, fun () -> take (n-1) (l' ()))
+
+let rec drop n (l:'a t) = match l with
+  | _ when n=0 -> l
+  | `Nil -> `Nil
+  | `Cons (_,l') -> drop (n-1) (l'())
+
+let rec map f l = match l with
+  | `Nil -> `Nil
+  | `Cons (x, l') -> `Cons (f x, fun () -> map f (l' ()))
+
+let rec fmap f (l:'a t):'b 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' ()))
+      end
+
+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' ())
+
+let rec append l1 l2 = match l1 with
+  | `Nil -> l2
+  | `Cons (x, l1') -> `Cons (x, fun () -> append (l1' ()) l2)
+
+let rec flat_map f l = match l with
+  | `Nil -> `Nil
+  | `Cons (x, l') ->
+      append (f x) (flat_map f (l' ()))
diff --git a/core/CCKList.mli b/core/CCKList.mli
new file mode 100644
index 00000000..7ed21cd2
--- /dev/null
+++ b/core/CCKList.mli
@@ -0,0 +1,63 @@
+(*
+Copyright (c) 2013, Simon Cruanes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.  Redistributions in binary
+form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with
+the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*)
+
+(** {1 Continuation List} *)
+
+type + 'a t =
+  [ `Nil
+  | `Cons of 'a * (unit -> 'a t)
+  ]
+
+val nil : 'a t
+
+val cons : 'a -> (unit -> 'a t) -> 'a t
+
+val to_list : 'a t -> 'a list
+  (** Gather all values into a list *)
+
+type 'a sequence = ('a -> unit) -> unit
+type 'a gen = unit -> 'a option
+
+val to_seq : 'a t -> 'a sequence
+val to_gen : 'a t -> 'a gen
+
+val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
+  (** Fold on values *)
+
+val length : 'a t -> int
+
+val take : int -> 'a t -> 'a t
+
+val drop : int -> 'a t -> 'a t
+
+val map : ('a -> 'b) -> 'a t -> 'b t
+
+val fmap : ('a -> 'b option) -> 'a t -> 'b t
+
+val filter : ('a -> bool) -> 'a t -> 'a t
+
+val append : 'a t -> 'a t -> 'a t
+
+val flat_map : ('a -> 'b t) -> 'a t -> 'b t
diff --git a/core/CCList.ml b/core/CCList.ml
index cad0c945..e368b280 100644
--- a/core/CCList.ml
+++ b/core/CCList.ml
@@ -379,6 +379,7 @@ end
 
 type 'a sequence = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
+type 'a klist = [`Nil | `Cons of 'a * (unit -> 'a klist)]
 type 'a printer = Buffer.t -> 'a -> unit
 type 'a formatter = Format.formatter -> 'a -> unit
 
@@ -408,6 +409,24 @@ let of_gen g =
   in
   direct _direct_depth g
 
+let to_klist l =
+  let rec make l () = match l with
+    | [] -> `Nil
+    | x::l' -> `Cons (x, make l')
+  in make l ()
+
+let of_klist l =
+  let rec direct i g =
+    if i = 0 then safe [] g
+    else match l with
+      | `Nil -> []
+      | `Cons (x,l') -> x :: direct (i-1) (l' ())
+  and safe acc l = match l with
+    | `Nil -> List.rev acc
+    | `Cons (x,l') -> safe (x::acc) (l' ())
+  in
+  direct _direct_depth l
+
 (** {2 IO} *)
 
 let pp ?(start="[") ?(stop="]") ?(sep=", ") pp_item buf l =
diff --git a/core/CCList.mli b/core/CCList.mli
index 0d84aac2..1691ed75 100644
--- a/core/CCList.mli
+++ b/core/CCList.mli
@@ -171,6 +171,7 @@ end
 
 type 'a sequence = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
+type 'a klist = [`Nil | `Cons of 'a * (unit -> 'a klist)]
 type 'a printer = Buffer.t -> 'a -> unit
 type 'a formatter = Format.formatter -> 'a -> unit
 
@@ -180,6 +181,9 @@ val of_seq : 'a sequence -> 'a t
 val to_gen : 'a t -> 'a gen
 val of_gen : 'a gen -> 'a t
 
+val to_klist : 'a t -> 'a klist
+val of_klist : 'a klist -> 'a t
+
 (** {2 IO} *)
 
 val pp : ?start:string -> ?stop:string -> ?sep:string ->