diff --git a/_oasis b/_oasis
index b1b672b3..895da459 100644
--- a/_oasis
+++ b/_oasis
@@ -84,6 +84,7 @@ Executable benchs
   Path: tests/
   Install: false
   CompiledObject: native
+  Build$: flag(bench)
   MainIs: benchs.ml
   BuildDepends: containers,bench
 
diff --git a/persistentHashtbl.ml b/persistentHashtbl.ml
index d5b7264d..9aa17080 100644
--- a/persistentHashtbl.ml
+++ b/persistentHashtbl.ml
@@ -69,11 +69,15 @@ module type S = sig
   val fold : ('b -> key -> 'a -> 'b) -> 'b -> 'a t -> 'b
     (** Fold over bindings *)
 
-  val of_gen : ?init:'a t -> (key * 'a) Gen.t -> 'a t
-    (** Add (replace) bindings from the generator to the table *)
+  val of_seq : ?init:'a t -> (key * 'a) Sequence.t -> 'a t
+    (** Add (replace) bindings from the sequence to the table *)
 
-  val to_gen : 'a t -> (key * 'a) Gen.t
-    (** Generator on the bindings of the table *)
+  val of_list : ?init:'a t -> (key * 'a) list -> 'a t
+
+  val to_seq : 'a t -> (key * 'a) Sequence.t
+    (** Sequence of the bindings of the table *)
+
+  val to_list : 'a t -> (key * 'a) list
 end
 
 (** {2 Implementation} *)
@@ -123,7 +127,9 @@ module Make(H : HashedType) : S with type key = H.t = struct
           Table.remove tbl key;
           k tbl)
     in
-    reroot t (fun x -> x)
+    match !t with
+    | Table tbl -> tbl
+    | _ -> reroot t (fun x -> x)
 
   let is_empty t =
     match !t with
@@ -196,17 +202,27 @@ module Make(H : HashedType) : S with type key = H.t = struct
     | _ -> reroot t in
     Table.fold (fun k v acc -> f acc k v) tbl acc
 
-  let of_gen ?init gen =
+  let of_seq ?init seq =
     let tbl = match init with
     | None -> Table.create 5
     | Some t -> Table.copy (reroot t) in
-    Gen.iter (fun (k,v) -> Table.replace tbl k v) gen;
+    Sequence.iter (fun (k,v) -> Table.replace tbl k v) seq;
     ref (Table tbl)
 
-  let to_gen t =
-    (* not efficient at the moment... *)
+  let of_list ?init l =
+    of_seq ?init (Sequence.of_list l)
+
+  let to_list t =
     let tbl = reroot t in
     let bindings = Table.fold (fun k v acc -> (k,v)::acc) tbl [] in
-    Gen.of_list bindings
+    bindings
+
+  let to_seq t =
+    fun k ->
+      let tbl = match !t with
+      | Table tbl -> tbl
+      | _ -> reroot t
+      in
+      Table.iter (fun x y -> k (x,y)) tbl
 end
 
diff --git a/persistentHashtbl.mli b/persistentHashtbl.mli
index cf991183..3ca89c08 100644
--- a/persistentHashtbl.mli
+++ b/persistentHashtbl.mli
@@ -69,11 +69,15 @@ module type S = sig
   val fold : ('b -> key -> 'a -> 'b) -> 'b -> 'a t -> 'b
     (** Fold over bindings *)
 
-  val of_gen : ?init:'a t -> (key * 'a) Gen.t -> 'a t
-    (** Add (replace) bindings from the generator to the table *)
+  val of_seq : ?init:'a t -> (key * 'a) Sequence.t -> 'a t
+    (** Add (replace) bindings from the sequence to the table *)
 
-  val to_gen : 'a t -> (key * 'a) Gen.t
-    (** Generator on the bindings of the table *)
+  val of_list : ?init:'a t -> (key * 'a) list -> 'a t
+
+  val to_seq : 'a t -> (key * 'a) Sequence.t
+    (** Sequence of the bindings of the table *)
+
+  val to_list : 'a t -> (key * 'a) list
 end
 
 (** {2 Implementation} *)
diff --git a/setup.ml b/setup.ml
index 7850723f..c826a7e2 100644
--- a/setup.ml
+++ b/setup.ml
@@ -1,7 +1,7 @@
 (* setup.ml generated for the first time by OASIS v0.3.0 *)
 
 (* OASIS_START *)
-(* DO NOT EDIT (digest: 55272ba3562c49c9ccb909d630d508a8) *)
+(* DO NOT EDIT (digest: c9341580de424a256871dd6b43247845) *)
 (*
    Regenerated by OASIS v0.3.0
    Visit http://oasis.forge.ocamlcore.org for more information and
@@ -6071,7 +6071,11 @@ let setup_t =
                      cs_plugin_data = [];
                      },
                    {
-                      bs_build = [(OASISExpr.EBool true, true)];
+                      bs_build =
+                        [
+                           (OASISExpr.EBool true, false);
+                           (OASISExpr.EFlag "bench", true)
+                        ];
                       bs_install = [(OASISExpr.EBool true, false)];
                       bs_path = "tests/";
                       bs_compiled_object = Native;
@@ -6219,7 +6223,7 @@ let setup_t =
           };
      oasis_fn = Some "_oasis";
      oasis_version = "0.3.0";
-     oasis_digest = Some "\177\020\012#dJ\255\130\019K\237\025\237\016l\020";
+     oasis_digest = Some "H\2095\254\2336\164\1606\140\2459^6o\218";
      oasis_exec = None;
      oasis_setup_args = [];
      setup_update = false;
@@ -6227,6 +6231,6 @@ let setup_t =
 
 let setup () = BaseSetup.setup setup_t;;
 
-# 6231 "setup.ml"
+# 6235 "setup.ml"
 (* OASIS_STOP *)
 let () = setup ();;