diff --git a/jscomp/others/.depend b/jscomp/others/.depend
index 221f3b9e3f..6ff549ebed 100644
--- a/jscomp/others/.depend
+++ b/jscomp/others/.depend
@@ -28,7 +28,7 @@ bs_internalBuckets.cmj : bs_internalBucketsType.cmj bs_Array.cmj
 bs_HashMap.cmj : bs_internalBucketsType.cmj bs_internalBuckets.cmj \
     bs_Hash.cmj bs_Bag.cmj bs_Array.cmj bs_HashMap.cmi
 bs_HashSet.cmj : bs_internalSetBuckets.cmj bs_internalBucketsType.cmj \
-    bs_Hash.cmj bs_Bag.cmj bs_Array.cmj bs_HashSet.cmi
+    bs_Hash.cmj bs_Bag.cmj bs_Array.cmj bs.cmj bs_HashSet.cmi
 bs_HashSetString.cmj : bs_internalSetBuckets.cmj bs_internalBucketsType.cmj \
     bs_Array.cmj bs.cmj bs_HashSetString.cmi
 bs_HashSetInt.cmj : bs_internalSetBuckets.cmj bs_internalBucketsType.cmj \
diff --git a/jscomp/others/bs_HashSet.ml b/jscomp/others/bs_HashSet.ml
index 1e9fee3f43..13036d71a3 100644
--- a/jscomp/others/bs_HashSet.ml
+++ b/jscomp/others/bs_HashSet.ml
@@ -197,3 +197,30 @@ let mem (type a) (type id) (h : (a,id) t) (key : a) =
   let module M = (val dict) in   
   mem0 ~hash:M.hash ~eq:M.eq data key   
 
+let ofArray0  ~hash ~eq arr  = 
+  let len = Bs.Array.length arr in 
+  let v = create0 len in 
+  for i = 0 to len - 1 do 
+    add0 ~eq ~hash v (Bs.Array.unsafe_get arr i)
+  done ;
+  v
+
+(* TOOD: optimize heuristics for resizing *)  
+let addArray0 ~hash ~eq  h arr =   
+  let len = Bs.Array.length arr in 
+  for i = 0 to len - 1 do 
+    add0 h  ~eq ~hash (Bs_Array.unsafe_get arr i)
+  done 
+
+let ofArray (type a) (type id)
+    ~dict:(dict:(a,id) Bs_Hash.t) arr =     
+  let module M = (val dict) in 
+  B.bag ~dict 
+    ~data:M.(ofArray0 ~eq~hash arr)
+
+let addArray (type a) (type id)
+    (h : (a,id) t) arr = 
+  let dict,data = B.(dict h, data h) in 
+  let module M = (val dict) in
+  M.(addArray0 ~hash ~eq data arr)
+
diff --git a/jscomp/others/bs_HashSet.mli b/jscomp/others/bs_HashSet.mli
index 11b64aa088..b8d3906db9 100644
--- a/jscomp/others/bs_HashSet.mli
+++ b/jscomp/others/bs_HashSet.mli
@@ -1,11 +1,9 @@
-
-
 type ('a, 'id) t0
 
 type ('a, 'id) t = 
-    (('a, 'id) Bs_Hash.t,
-     ('a, 'id) t0) Bs_Bag.bag 
-  
+  (('a, 'id) Bs_Hash.t,
+   ('a, 'id) t0) Bs_Bag.bag 
+
 (** The type of hash tables from type ['a] to type ['b]. *)
 
 val create0 : int -> ('a, 'id) t0
@@ -62,9 +60,9 @@ val reset : ('a, 'id) t -> unit
 
 
 val add0 :
- hash:('a,'id) Bs_Hash.hash ->
- eq:('a,'id) Bs_Hash.eq -> 
- ('a,'id) t0 -> 'a ->  unit
+  hash:('a,'id) Bs_Hash.hash ->
+  eq:('a,'id) Bs_Hash.eq -> 
+  ('a,'id) t0 -> 'a ->  unit
 val add : ('a, 'id) t -> 'a -> unit
 (** [Hashtbl.add tbl x y] adds a binding of [x] to [y] in table [tbl].
     Previous bindings for [x] are not removed, but simply
@@ -85,13 +83,13 @@ val remove0:
   eq:('a,'id) Bs_Hash.eq -> 
   ('a, 'id) t0 -> 'a -> unit
 val remove:
-('a, 'id) t -> 'a -> unit
+  ('a, 'id) t -> 'a -> unit
 (** [Hashtbl.remove tbl x] removes the current binding of [x] in [tbl],
     restoring the previous binding if it exists.
     It does nothing if [x] is not bound in [tbl]. *)
 
 
-    
+
 
 val iter0 : ('a -> unit [@bs]) -> ('a, 'id) t0 -> unit
 val iter : ('a  -> unit [@bs]) -> ('a, 'id) t -> unit
@@ -129,7 +127,7 @@ val fold : ('a  -> 'c -> 'c [@bs]) -> ('a, 'id) t -> 'c -> 'c
     of OCaml.  For randomized hash tables, the order of enumeration
     is entirely random. *)
 
-  
+
 val length0 : ('a, 'id) t0 -> int
 val length  : ('a, 'id) t -> int  
 (** [Hashtbl.length tbl] returns the number of bindings in [tbl].
@@ -180,3 +178,22 @@ val logStats : _ t -> unit
 
 val toArray0 : ('a,'id) t0 -> 'a array
 val toArray : ('a,'id) t -> 'a array 
+
+val ofArray0 : 
+  hash:('a,'id) Bs_Hash.hash  -> 
+  eq:('a,'id) Bs_Hash.eq -> 
+  'a array -> 
+  ('a, 'id) t0      
+
+val ofArray :   
+  dict:('a,'id) Bs_Hash.t -> 
+  'a array -> 
+  ('a,'id) t 
+
+val addArray0 : 
+  hash:('a,'id) Bs_Hash.hash  -> 
+  eq:('a,'id) Bs_Hash.eq -> 
+  ('a,'id) t0 -> 'a array -> unit     
+
+val addArray:   
+   ('a,'id) t -> 'a array -> unit   
\ No newline at end of file
diff --git a/jscomp/others/bs_HashSetInt.ml b/jscomp/others/bs_HashSetInt.ml
index 3169f87932..41c9727c11 100644
--- a/jscomp/others/bs_HashSetInt.ml
+++ b/jscomp/others/bs_HashSetInt.ml
@@ -143,4 +143,11 @@ let ofArray arr  =
   for i = 0 to len - 1 do 
     add v (Bs.Array.unsafe_get arr i)
   done ;
-  v
\ No newline at end of file
+  v
+
+(* TOOD: optimize heuristics for resizing *)  
+let addArray h arr =   
+  let len = Bs.Array.length arr in 
+  for i = 0 to len - 1 do 
+    add h (Bs_Array.unsafe_get arr i)
+done 
\ No newline at end of file
diff --git a/jscomp/others/bs_HashSetInt.mli b/jscomp/others/bs_HashSetInt.mli
index 208433545c..979837d100 100644
--- a/jscomp/others/bs_HashSetInt.mli
+++ b/jscomp/others/bs_HashSetInt.mli
@@ -170,4 +170,6 @@ val logStats : t -> unit
 
 val toArray : t -> key array 
 
-val ofArray : key array -> t 
\ No newline at end of file
+val ofArray : key array -> t 
+
+val addArray : t -> key array -> unit 
\ No newline at end of file
diff --git a/jscomp/others/bs_HashSetString.ml b/jscomp/others/bs_HashSetString.ml
index 5ae5dfa9ca..3a71ce1860 100644
--- a/jscomp/others/bs_HashSetString.ml
+++ b/jscomp/others/bs_HashSetString.ml
@@ -143,4 +143,11 @@ let ofArray arr  =
   for i = 0 to len - 1 do 
     add v (Bs.Array.unsafe_get arr i)
   done ;
-  v
\ No newline at end of file
+  v
+
+(* TOOD: optimize heuristics for resizing *)  
+let addArray h arr =   
+  let len = Bs.Array.length arr in 
+  for i = 0 to len - 1 do 
+    add h (Bs_Array.unsafe_get arr i)
+done 
\ No newline at end of file
diff --git a/jscomp/others/bs_HashSetString.mli b/jscomp/others/bs_HashSetString.mli
index b66051f161..5e5b82d8a6 100644
--- a/jscomp/others/bs_HashSetString.mli
+++ b/jscomp/others/bs_HashSetString.mli
@@ -170,4 +170,6 @@ val logStats : t -> unit
 
 val toArray : t -> key array 
 
-val ofArray : key array -> t 
\ No newline at end of file
+val ofArray : key array -> t 
+
+val addArray : t -> key array -> unit 
\ No newline at end of file
diff --git a/jscomp/others/hashset.cppo.ml b/jscomp/others/hashset.cppo.ml
index 6f07f30843..a22ffcb2ab 100644
--- a/jscomp/others/hashset.cppo.ml
+++ b/jscomp/others/hashset.cppo.ml
@@ -14,7 +14,7 @@ let hash (s : key) =
   final_mix (caml_hash_mix_int 0 s)
             #else 
   [%error "unknown type"]
-#endif
+  #endif
 
 module N = Bs_internalSetBuckets
 module C = Bs_internalBucketsType
@@ -152,4 +152,11 @@ let ofArray arr  =
   for i = 0 to len - 1 do 
     add v (Bs.Array.unsafe_get arr i)
   done ;
-  v
\ No newline at end of file
+  v
+
+(* TOOD: optimize heuristics for resizing *)  
+let addArray h arr =   
+  let len = Bs.Array.length arr in 
+  for i = 0 to len - 1 do 
+    add h (Bs_Array.unsafe_get arr i)
+done 
\ No newline at end of file
diff --git a/jscomp/others/hashset.cppo.mli b/jscomp/others/hashset.cppo.mli
index 7cd0d1f713..74e4b66861 100644
--- a/jscomp/others/hashset.cppo.mli
+++ b/jscomp/others/hashset.cppo.mli
@@ -174,4 +174,6 @@ val logStats : t -> unit
 
 val toArray : t -> key array 
 
-val ofArray : key array -> t 
\ No newline at end of file
+val ofArray : key array -> t 
+
+val addArray : t -> key array -> unit 
\ No newline at end of file
diff --git a/jscomp/test/bs_hashset_int_test.js b/jscomp/test/bs_hashset_int_test.js
index a3cb648510..89dde3137d 100644
--- a/jscomp/test/bs_hashset_int_test.js
+++ b/jscomp/test/bs_hashset_int_test.js
@@ -38,6 +38,26 @@ var xs = Bs_SetInt.toArray(Bs_SetInt.ofArray(Bs_HashSetInt.toArray(v)));
 
 eq("File \"bs_hashset_int_test.ml\", line 19, characters 5-12", xs, Array_data_util.range(30, 120));
 
+var u$1 = Bs_Array.append(Array_data_util.randomRange(0, 100000), Array_data_util.randomRange(0, 100));
+
+var v$1 = Bs_HashSetInt.create(40);
+
+Bs_HashSetInt.addArray(v$1, u$1);
+
+eq("File \"bs_hashset_int_test.ml\", line 25, characters 5-12", Bs_HashSetInt.length(v$1), 100001);
+
+for(var i = 0; i <= 1000; ++i){
+  Bs_HashSetInt.remove(v$1, i);
+}
+
+eq("File \"bs_hashset_int_test.ml\", line 29, characters 5-12", Bs_HashSetInt.length(v$1), 99000);
+
+for(var i$1 = 0; i$1 <= 2000; ++i$1){
+  Bs_HashSetInt.remove(v$1, i$1);
+}
+
+eq("File \"bs_hashset_int_test.ml\", line 33, characters 5-12", Bs_HashSetInt.length(v$1), 98000);
+
 Mt.from_pair_suites("bs_hashset_int_test.ml", suites[0]);
 
 var N = 0;
diff --git a/jscomp/test/bs_hashset_int_test.ml b/jscomp/test/bs_hashset_int_test.ml
index 0783a598fc..9d61af6547 100644
--- a/jscomp/test/bs_hashset_int_test.ml
+++ b/jscomp/test/bs_hashset_int_test.ml
@@ -17,5 +17,18 @@ let () =
   eq __LOC__ (N.length v) 91 ;  
   let xs = S.toArray (S.ofArray (N.toArray v)) in 
   eq __LOC__ xs (I.range 30 120)
+
+let () =
+  let u = I.randomRange 0 100_000 ++ I.randomRange 0 100 in 
+  let v = N.create 40 in 
+  N.addArray v u ;
+  eq __LOC__ (N.length v) 100_001;
+  for i = 0 to 1_000 do  
+    N.remove v i 
+  done ; 
+  eq __LOC__ (N.length v ) 99_000;
+  for i = 0 to 2_000 do  
+    N.remove v i 
+  done ; 
+  eq __LOC__ (N.length v ) 98_000
 let () = Mt.from_pair_suites __FILE__ !suites
-    
\ No newline at end of file
diff --git a/lib/js/bs_HashSet.js b/lib/js/bs_HashSet.js
index ac28f1e3b5..3902f0878b 100644
--- a/lib/js/bs_HashSet.js
+++ b/lib/js/bs_HashSet.js
@@ -212,6 +212,36 @@ function mem(h, key) {
   return mem0(dict[/* hash */0], dict[/* eq */1], data, key);
 }
 
+function ofArray0(hash, eq, arr) {
+  var len = arr.length;
+  var v = Bs_internalBucketsType.create0(len);
+  for(var i = 0 ,i_finish = len - 1 | 0; i <= i_finish; ++i){
+    add0(hash, eq, v, arr[i]);
+  }
+  return v;
+}
+
+function addArray0(hash, eq, h, arr) {
+  var len = arr.length;
+  for(var i = 0 ,i_finish = len - 1 | 0; i <= i_finish; ++i){
+    add0(hash, eq, h, arr[i]);
+  }
+  return /* () */0;
+}
+
+function ofArray(dict, arr) {
+  return {
+          dict: dict,
+          data: ofArray0(dict[/* hash */0], dict[/* eq */1], arr)
+        };
+}
+
+function addArray(h, arr) {
+  var dict = h.dict;
+  var data = h.data;
+  return addArray0(dict[/* hash */0], dict[/* eq */1], data, arr);
+}
+
 var create0 = Bs_internalBucketsType.create0;
 
 var clear0 = Bs_internalBucketsType.clear0;
@@ -250,4 +280,8 @@ exports.logStats0 = logStats0;
 exports.logStats  = logStats;
 exports.toArray0  = toArray0;
 exports.toArray   = toArray;
+exports.ofArray0  = ofArray0;
+exports.ofArray   = ofArray;
+exports.addArray0 = addArray0;
+exports.addArray  = addArray;
 /* Bs_internalBucketsType Not a pure module */
diff --git a/lib/js/bs_HashSetInt.js b/lib/js/bs_HashSetInt.js
index 239cbacb2c..d5a57f4e72 100644
--- a/lib/js/bs_HashSetInt.js
+++ b/lib/js/bs_HashSetInt.js
@@ -174,6 +174,14 @@ function ofArray(arr) {
   return v;
 }
 
+function addArray(h, arr) {
+  var len = arr.length;
+  for(var i = 0 ,i_finish = len - 1 | 0; i <= i_finish; ++i){
+    add(h, arr[i]);
+  }
+  return /* () */0;
+}
+
 var create = Bs_internalBucketsType.create0;
 
 var clear = Bs_internalBucketsType.clear0;
@@ -202,4 +210,5 @@ exports.length   = length;
 exports.logStats = logStats;
 exports.toArray  = toArray;
 exports.ofArray  = ofArray;
+exports.addArray = addArray;
 /* Bs_internalBucketsType Not a pure module */
diff --git a/lib/js/bs_HashSetString.js b/lib/js/bs_HashSetString.js
index a88a93f779..342c4b36ad 100644
--- a/lib/js/bs_HashSetString.js
+++ b/lib/js/bs_HashSetString.js
@@ -174,6 +174,14 @@ function ofArray(arr) {
   return v;
 }
 
+function addArray(h, arr) {
+  var len = arr.length;
+  for(var i = 0 ,i_finish = len - 1 | 0; i <= i_finish; ++i){
+    add(h, arr[i]);
+  }
+  return /* () */0;
+}
+
 var create = Bs_internalBucketsType.create0;
 
 var clear = Bs_internalBucketsType.clear0;
@@ -202,4 +210,5 @@ exports.length   = length;
 exports.logStats = logStats;
 exports.toArray  = toArray;
 exports.ofArray  = ofArray;
+exports.addArray = addArray;
 /* Bs_internalBucketsType Not a pure module */