diff --git a/src/core/CCHashtbl.ml b/src/core/CCHashtbl.ml
index 832d8682..14f64c9c 100644
--- a/src/core/CCHashtbl.ml
+++ b/src/core/CCHashtbl.ml
@@ -10,131 +10,135 @@ type 'a printer = Format.formatter -> 'a -> unit
 
 (** {2 Polymorphic tables} *)
 
-let get tbl x =
-  try Some (Hashtbl.find tbl x)
-  with Not_found -> None
+module Poly = struct
+  let get tbl x =
+    try Some (Hashtbl.find tbl x)
+    with Not_found -> None
 
-let get_or tbl x ~default =
-  try Hashtbl.find tbl x
-  with Not_found -> default
+  let get_or tbl x ~default =
+    try Hashtbl.find tbl x
+    with Not_found -> default
 
-(*$=
-  "c" (let tbl = of_list [1,"a"; 2,"b"] in get_or tbl 3 ~default:"c")
-  "b" (let tbl = of_list [1,"a"; 2,"b"] in get_or tbl 2 ~default:"c")
-*)
+  (*$=
+    "c" (let tbl = of_list [1,"a"; 2,"b"] in get_or tbl 3 ~default:"c")
+    "b" (let tbl = of_list [1,"a"; 2,"b"] in get_or tbl 2 ~default:"c")
+  *)
 
-let keys tbl k = Hashtbl.iter (fun key _ -> k key) tbl
+  let keys tbl k = Hashtbl.iter (fun key _ -> k key) tbl
 
-let values tbl k = Hashtbl.iter (fun _ v -> k v) tbl
+  let values tbl k = Hashtbl.iter (fun _ v -> k v) tbl
 
-let keys_list tbl = Hashtbl.fold (fun k _ a -> k::a) tbl []
-let values_list tbl = Hashtbl.fold (fun _ v a -> v::a) tbl []
+  let keys_list tbl = Hashtbl.fold (fun k _ a -> k::a) tbl []
+  let values_list tbl = Hashtbl.fold (fun _ v a -> v::a) tbl []
 
-let add_list tbl k v =
-  let l = try Hashtbl.find tbl k with Not_found -> [] in
-  Hashtbl.replace tbl k (v::l)
+  let add_list tbl k v =
+    let l = try Hashtbl.find tbl k with Not_found -> [] in
+    Hashtbl.replace tbl k (v::l)
 
-let incr ?(by=1) tbl x =
-  let n = get_or tbl x ~default:0 in
-  if n+by <= 0
-  then Hashtbl.remove tbl x
-  else Hashtbl.replace tbl x (n+by)
-
-let decr ?(by=1) tbl x =
-  try
-    let n = Hashtbl.find tbl x in
-    if n-by <= 0
+  let incr ?(by=1) tbl x =
+    let n = get_or tbl x ~default:0 in
+    if n+by <= 0
     then Hashtbl.remove tbl x
-    else Hashtbl.replace tbl x (n-by)
-  with Not_found -> ()
+    else Hashtbl.replace tbl x (n+by)
 
-let map_list f h =
-  Hashtbl.fold
-    (fun x y acc -> f x y :: acc)
-    h []
+  let decr ?(by=1) tbl x =
+    try
+      let n = Hashtbl.find tbl x in
+      if n-by <= 0
+      then Hashtbl.remove tbl x
+      else Hashtbl.replace tbl x (n-by)
+    with Not_found -> ()
 
-(*$T
-  of_list [1,"a"; 2,"b"] |> map_list (fun x y -> string_of_int x ^ y) \
-    |> List.sort Pervasives.compare = ["1a"; "2b"]
-*)
+  let map_list f h =
+    Hashtbl.fold
+      (fun x y acc -> f x y :: acc)
+      h []
 
-let to_seq tbl k = Hashtbl.iter (fun key v -> k (key,v)) tbl
+  (*$T
+    of_list [1,"a"; 2,"b"] |> map_list (fun x y -> string_of_int x ^ y) \
+      |> List.sort Pervasives.compare = ["1a"; "2b"]
+  *)
 
-let add_seq tbl seq = seq (fun (k,v) -> Hashtbl.add tbl k v)
+  let to_seq tbl k = Hashtbl.iter (fun key v -> k (key,v)) tbl
 
-let of_seq seq =
-  let tbl = Hashtbl.create 32 in
-  add_seq tbl seq;
-  tbl
+  let add_seq tbl seq = seq (fun (k,v) -> Hashtbl.add tbl k v)
 
-let add_seq_count tbl seq = seq (fun k -> incr tbl k)
+  let of_seq seq =
+    let tbl = Hashtbl.create 32 in
+    add_seq tbl seq;
+    tbl
 
-let of_seq_count seq =
-  let tbl = Hashtbl.create 32 in
-  add_seq_count tbl seq;
-  tbl
+  let add_seq_count tbl seq = seq (fun k -> incr tbl k)
 
-let to_list tbl =
-  Hashtbl.fold
-    (fun k v l -> (k,v) :: l)
-    tbl []
+  let of_seq_count seq =
+    let tbl = Hashtbl.create 32 in
+    add_seq_count tbl seq;
+    tbl
 
-let of_list l =
-  let tbl = Hashtbl.create 32 in
-  List.iter (fun (k,v) -> Hashtbl.add tbl k v) l;
-  tbl
+  let to_list tbl =
+    Hashtbl.fold
+      (fun k v l -> (k,v) :: l)
+      tbl []
 
-let update tbl ~f ~k =
-  let v = get tbl k in
-  match v, f k v with
-    | None, None -> ()
-    | None, Some v' -> Hashtbl.add tbl k v'
-    | Some _, Some v' -> Hashtbl.replace tbl k v'
-    | Some _, None -> Hashtbl.remove tbl k
+  let of_list l =
+    let tbl = Hashtbl.create 32 in
+    List.iter (fun (k,v) -> Hashtbl.add tbl k v) l;
+    tbl
 
-(*$R
-  let tbl = Hashtbl.create 32 in
-  update tbl ~k:1 ~f:(fun _ _ -> Some "1");
-  assert_equal (Some "1") (get tbl 1);
-  update tbl ~k:2 ~f:(fun _ v->match v with Some _ -> assert false | None -> Some "2");
-  assert_equal (Some "2") (get tbl 2);
-  assert_equal 2 (Hashtbl.length tbl);
-  update tbl ~k:1 ~f:(fun _ _ -> None);
-  assert_equal None (get tbl 1);
-*)
+  let update tbl ~f ~k =
+    let v = get tbl k in
+    match v, f k v with
+      | None, None -> ()
+      | None, Some v' -> Hashtbl.add tbl k v'
+      | Some _, Some v' -> Hashtbl.replace tbl k v'
+      | Some _, None -> Hashtbl.remove tbl k
 
-let get_or_add tbl ~f ~k =
-  try Hashtbl.find tbl k
-  with Not_found ->
-    let v = f k in
-    Hashtbl.add tbl k v;
-    v
+  (*$R
+    let tbl = Hashtbl.create 32 in
+    update tbl ~k:1 ~f:(fun _ _ -> Some "1");
+    assert_equal (Some "1") (get tbl 1);
+    update tbl ~k:2 ~f:(fun _ v->match v with Some _ -> assert false | None -> Some "2");
+    assert_equal (Some "2") (get tbl 2);
+    assert_equal 2 (Hashtbl.length tbl);
+    update tbl ~k:1 ~f:(fun _ _ -> None);
+    assert_equal None (get tbl 1);
+  *)
 
-(*$R
-  let tbl = Hashtbl.create 32 in
-  let v1 = get_or_add tbl ~k:1 ~f:(fun _ -> "1") in
-  assert_equal "1" v1;
-  assert_equal (Some "1") (get tbl 1);
-  let v2 = get_or_add tbl ~k:2 ~f:(fun _ ->"2") in
-  assert_equal "2" v2;
-  assert_equal (Some "2") (get tbl 2);
-  assert_equal "2" (get_or_add tbl ~k:2 ~f:(fun _ -> assert false));
-  assert_equal 2 (Hashtbl.length tbl);
-  ()
-*)
+  let get_or_add tbl ~f ~k =
+    try Hashtbl.find tbl k
+    with Not_found ->
+      let v = f k in
+      Hashtbl.add tbl k v;
+      v
 
-let print pp_k pp_v fmt m =
-  Format.fprintf fmt "@[<hov2>tbl {@,";
-  let first = ref true in
-  Hashtbl.iter
-    (fun k v ->
-       if !first then first := false else Format.pp_print_string fmt ", ";
-       pp_k fmt k;
-       Format.pp_print_string fmt " -> ";
-       pp_v fmt v;
-       Format.pp_print_cut fmt ()
-    ) m;
-  Format.fprintf fmt "}@]"
+  (*$R
+    let tbl = Hashtbl.create 32 in
+    let v1 = get_or_add tbl ~k:1 ~f:(fun _ -> "1") in
+    assert_equal "1" v1;
+    assert_equal (Some "1") (get tbl 1);
+    let v2 = get_or_add tbl ~k:2 ~f:(fun _ ->"2") in
+    assert_equal "2" v2;
+    assert_equal (Some "2") (get tbl 2);
+    assert_equal "2" (get_or_add tbl ~k:2 ~f:(fun _ -> assert false));
+    assert_equal 2 (Hashtbl.length tbl);
+    ()
+  *)
+
+  let print pp_k pp_v fmt m =
+    Format.fprintf fmt "@[<hov2>tbl {@,";
+    let first = ref true in
+    Hashtbl.iter
+      (fun k v ->
+         if !first then first := false else Format.pp_print_string fmt ", ";
+         pp_k fmt k;
+         Format.pp_print_string fmt " -> ";
+         pp_v fmt v;
+         Format.pp_print_cut fmt ()
+      ) m;
+    Format.fprintf fmt "}@]"
+end
+
+include Poly
 
 (** {2 Functor} *)
 
diff --git a/src/core/CCHashtbl.mli b/src/core/CCHashtbl.mli
index 54163e81..484cca45 100644
--- a/src/core/CCHashtbl.mli
+++ b/src/core/CCHashtbl.mli
@@ -12,96 +12,102 @@ type 'a printer = Format.formatter -> 'a -> unit
 
 (** {2 Polymorphic tables} *)
 
-val get : ('a,'b) Hashtbl.t -> 'a -> 'b option
-(** Safe version of {!Hashtbl.find} *)
+(** This sub-module contains the extension of the standard polymorphic hashtbl. *)
 
-val get_or : ('a,'b) Hashtbl.t -> 'a -> default:'b -> 'b
-(** [get_or tbl k ~default] returns the value associated to [k] if present,
-    and returns [default] otherwise (if [k] doesn't belong in [tbl])
-    @since 0.16 *)
+module Poly : sig
+  val get : ('a,'b) Hashtbl.t -> 'a -> 'b option
+  (** Safe version of {!Hashtbl.find} *)
 
-val keys : ('a,'b) Hashtbl.t -> 'a sequence
-(** Iterate on keys (similar order as {!Hashtbl.iter}) *)
+  val get_or : ('a,'b) Hashtbl.t -> 'a -> default:'b -> 'b
+  (** [get_or tbl k ~default] returns the value associated to [k] if present,
+      and returns [default] otherwise (if [k] doesn't belong in [tbl])
+      @since 0.16 *)
 
-val values : ('a,'b) Hashtbl.t -> 'b sequence
-(** Iterate on values in the table *)
+  val keys : ('a,'b) Hashtbl.t -> 'a sequence
+  (** Iterate on keys (similar order as {!Hashtbl.iter}) *)
 
-val keys_list : ('a, 'b) Hashtbl.t -> 'a list
-(** [keys_list t] is the list of keys in [t].
-    @since 0.8 *)
+  val values : ('a,'b) Hashtbl.t -> 'b sequence
+  (** Iterate on values in the table *)
 
-val values_list : ('a, 'b) Hashtbl.t -> 'b list
-(** [values_list t] is the list of values in [t].
-    @since 0.8 *)
+  val keys_list : ('a, 'b) Hashtbl.t -> 'a list
+  (** [keys_list t] is the list of keys in [t].
+      @since 0.8 *)
 
-val map_list : ('a -> 'b -> 'c) -> ('a, 'b) Hashtbl.t -> 'c list
-(** Map on a hashtable's items, collect into a list *)
+  val values_list : ('a, 'b) Hashtbl.t -> 'b list
+  (** [values_list t] is the list of values in [t].
+      @since 0.8 *)
 
-val incr : ?by:int -> ('a, int) Hashtbl.t -> 'a -> unit
-(** [incr ?by tbl x] increments or initializes the counter associated with [x].
-    If [get tbl x = None], then after update, [get tbl x = Some 1];
-    otherwise, if [get tbl x = Some n], now [get tbl x = Some (n+1)].
-    @param by if specified, the int value is incremented by [by] rather than 1
-    @since 0.16 *)
+  val map_list : ('a -> 'b -> 'c) -> ('a, 'b) Hashtbl.t -> 'c list
+  (** Map on a hashtable's items, collect into a list *)
 
-val decr : ?by:int -> ('a, int) Hashtbl.t -> 'a -> unit
-(** Same as {!incr} but substract 1 (or the value of [by]).
-    If the value reaches 0, the key is removed from the table.
-    This does nothing if the key is not already present in the table.
-    @since 0.16 *)
+  val incr : ?by:int -> ('a, int) Hashtbl.t -> 'a -> unit
+  (** [incr ?by tbl x] increments or initializes the counter associated with [x].
+      If [get tbl x = None], then after update, [get tbl x = Some 1];
+      otherwise, if [get tbl x = Some n], now [get tbl x = Some (n+1)].
+      @param by if specified, the int value is incremented by [by] rather than 1
+      @since 0.16 *)
 
-val to_seq : ('a,'b) Hashtbl.t -> ('a * 'b) sequence
-(** Iterate on bindings in the table *)
+  val decr : ?by:int -> ('a, int) Hashtbl.t -> 'a -> unit
+  (** Same as {!incr} but substract 1 (or the value of [by]).
+      If the value reaches 0, the key is removed from the table.
+      This does nothing if the key is not already present in the table.
+      @since 0.16 *)
 
-val add_list : ('a, 'b list) Hashtbl.t -> 'a -> 'b -> unit
-(** [add_list tbl x y] adds [y] to the list [x] is bound to. If [x] is
-    not bound, it becomes bound to [[y]].
-    @since 0.16 *)
+  val to_seq : ('a,'b) Hashtbl.t -> ('a * 'b) sequence
+  (** Iterate on bindings in the table *)
 
-val add_seq : ('a,'b) Hashtbl.t -> ('a * 'b) sequence -> unit
-(** Add the corresponding pairs to the table, using {!Hashtbl.add}.
-    @since 0.16 *)
+  val add_list : ('a, 'b list) Hashtbl.t -> 'a -> 'b -> unit
+  (** [add_list tbl x y] adds [y] to the list [x] is bound to. If [x] is
+      not bound, it becomes bound to [[y]].
+      @since 0.16 *)
 
-val of_seq : ('a * 'b) sequence -> ('a,'b) Hashtbl.t
-(** From the given bindings, added in order *)
+  val add_seq : ('a,'b) Hashtbl.t -> ('a * 'b) sequence -> unit
+  (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
+      @since 0.16 *)
 
-val add_seq_count : ('a, int) Hashtbl.t -> 'a sequence -> unit
-(** [add_seq_count tbl seq] increments the count of each element of [seq]
-    by calling {!incr}. This is useful for counting how many times each
-    element of [seq] occurs.
-    @since 0.16 *)
+  val of_seq : ('a * 'b) sequence -> ('a,'b) Hashtbl.t
+  (** From the given bindings, added in order *)
 
-val of_seq_count : 'a sequence -> ('a, int) Hashtbl.t
-(** Similar to {!add_seq_count}, but allocates a new table and returns it
-    @since 0.16 *)
+  val add_seq_count : ('a, int) Hashtbl.t -> 'a sequence -> unit
+  (** [add_seq_count tbl seq] increments the count of each element of [seq]
+      by calling {!incr}. This is useful for counting how many times each
+      element of [seq] occurs.
+      @since 0.16 *)
 
-val to_list : ('a,'b) Hashtbl.t -> ('a * 'b) list
-(** List of bindings (order unspecified)  *)
+  val of_seq_count : 'a sequence -> ('a, int) Hashtbl.t
+  (** Similar to {!add_seq_count}, but allocates a new table and returns it
+      @since 0.16 *)
 
-val of_list : ('a * 'b) list -> ('a,'b) Hashtbl.t
-(** Build a table from the given list of bindings [k_i -> v_i],
-    added in order using {!add}. If a key occurs several times,
-    it will be added several times, and the visible binding
-    will be the last one. *)
+  val to_list : ('a,'b) Hashtbl.t -> ('a * 'b) list
+  (** List of bindings (order unspecified)  *)
 
-val update : ('a, 'b) Hashtbl.t -> f:('a -> 'b option -> 'b option) -> k:'a -> unit
-(** [update tbl ~f ~k] updates key [k] by calling [f k (Some v)] if
-    [k] was mapped to [v], or [f k None] otherwise; if the call
-    returns [None] then [k] is removed/stays removed, if the call
-    returns [Some v'] then the binding [k -> v'] is inserted
-    using {!Hashtbl.replace}
-    @since 0.14 *)
+  val of_list : ('a * 'b) list -> ('a,'b) Hashtbl.t
+  (** Build a table from the given list of bindings [k_i -> v_i],
+      added in order using {!add}. If a key occurs several times,
+      it will be added several times, and the visible binding
+      will be the last one. *)
 
-val get_or_add : ('a, 'b) Hashtbl.t -> f:('a -> 'b) -> k:'a -> 'b
-(** [get_or_add tbl ~k ~f] finds and returns the binding of [k]
-    in [tbl], if it exists. If it does not exist, then [f k]
-    is called to obtain a new binding [v]; [k -> v] is added
-    to [tbl] and [v] is returned.
-    @since NEXT_RELEASE *)
+  val update : ('a, 'b) Hashtbl.t -> f:('a -> 'b option -> 'b option) -> k:'a -> unit
+  (** [update tbl ~f ~k] updates key [k] by calling [f k (Some v)] if
+      [k] was mapped to [v], or [f k None] otherwise; if the call
+      returns [None] then [k] is removed/stays removed, if the call
+      returns [Some v'] then the binding [k -> v'] is inserted
+      using {!Hashtbl.replace}
+      @since 0.14 *)
 
-val print : 'a printer -> 'b printer -> ('a, 'b) Hashtbl.t printer
-(** Printer for table
-    @since 0.13 *)
+  val get_or_add : ('a, 'b) Hashtbl.t -> f:('a -> 'b) -> k:'a -> 'b
+  (** [get_or_add tbl ~k ~f] finds and returns the binding of [k]
+      in [tbl], if it exists. If it does not exist, then [f k]
+      is called to obtain a new binding [v]; [k -> v] is added
+      to [tbl] and [v] is returned.
+      @since NEXT_RELEASE *)
+
+  val print : 'a printer -> 'b printer -> ('a, 'b) Hashtbl.t printer
+  (** Printer for table
+      @since 0.13 *)
+end
+
+include module type of Poly
 
 (** {2 Functor} *)
 
diff --git a/src/core/containers.ml b/src/core/containers.ml
index 79bdf24a..1373d929 100644
--- a/src/core/containers.ml
+++ b/src/core/containers.ml
@@ -44,7 +44,7 @@ module Hashtbl = struct
      and module Make = Hashtbl.Make
      and type ('a,'b) t = ('a,'b) Hashtbl.t
   )
-  (* still unable to include CCHashtbl itself, for the polymorphic functions *)
+  include CCHashtbl.Poly
   module type S' = CCHashtbl.S
   module Make' = CCHashtbl.Make
 end