diff --git a/jscomp/others/.depend b/jscomp/others/.depend
index 2863cfe77d..79615d75f3 100644
--- a/jscomp/others/.depend
+++ b/jscomp/others/.depend
@@ -17,9 +17,9 @@ js_console.cmj :
 js_result.cmj : js_result.cmi
 js_mapperRt.cmj : js_mapperRt.cmi
 bs_Array.cmj : js_math.cmj bs_Array.cmi
-bs_internalAVLset.cmj : bs_SortArray.cmj bs_Dict.cmj bs_Array.cmj \
+bs_internalAVLset.cmj : bs_SortArray.cmj bs_Id.cmj bs_Array.cmj \
     bs_internalAVLset.cmi
-bs_internalAVLtree.cmj : bs_SortArray.cmj bs_Dict.cmj bs_Array.cmj \
+bs_internalAVLtree.cmj : bs_SortArray.cmj bs_Id.cmj bs_Array.cmj \
     bs_internalAVLtree.cmi
 bs_List.cmj : bs_Array.cmj bs_List.cmi
 bs_SortArray.cmj : bs_SortArrayString.cmj bs_SortArrayInt.cmj bs_Array.cmj \
@@ -32,22 +32,20 @@ bs_internalSetBuckets.cmj : bs_internalBucketsType.cmj bs_Array.cmj bs.cmj \
     bs_internalSetBuckets.cmi
 bs_internalBuckets.cmj : bs_internalBucketsType.cmj bs_Array.cmj \
     bs_internalBuckets.cmi
-bs_HashMap.cmj : bs_internalBucketsType.cmj bs_internalBuckets.cmj \
-    bs_HashMapString.cmj bs_HashMapInt.cmj bs_Dict.cmj bs_Array.cmj \
-    bs_HashMap.cmi
+bs_HashMap.cmj : bs_internalBucketsType.cmj bs_internalBuckets.cmj bs_Id.cmj \
+    bs_HashMapString.cmj bs_HashMapInt.cmj bs_Array.cmj bs_HashMap.cmi
 bs_HashSet.cmj : bs_internalSetBuckets.cmj bs_internalBucketsType.cmj \
-    bs_HashSetString.cmj bs_HashSetInt.cmj bs_Dict.cmj bs_Array.cmj \
+    bs_Id.cmj bs_HashSetString.cmj bs_HashSetInt.cmj bs_Array.cmj \
     bs_HashSet.cmi
 bs_HashSetString.cmj : bs_internalSetBuckets.cmj bs_internalBucketsType.cmj \
     bs_Array.cmj bs_HashSetString.cmi
 bs_HashSetInt.cmj : bs_internalSetBuckets.cmj bs_internalBucketsType.cmj \
     bs_Array.cmj bs_HashSetInt.cmi
-bs_Dict.cmj : bs_Dict.cmi
-bs_MapDict.cmj : bs_internalAVLtree.cmj bs_Dict.cmj bs_Array.cmj \
+bs_Id.cmj : bs_Id.cmi
+bs_MapDict.cmj : bs_internalAVLtree.cmj bs_Id.cmj bs_Array.cmj \
     bs_MapDict.cmi
-bs_SetDict.cmj : bs_internalAVLset.cmj bs_Dict.cmj bs_Array.cmj \
-    bs_SetDict.cmi
-bs_Map.cmj : bs_MapString.cmj bs_MapInt.cmj bs_MapDict.cmj bs_Dict.cmj \
+bs_SetDict.cmj : bs_internalAVLset.cmj bs_Id.cmj bs_Array.cmj bs_SetDict.cmi
+bs_Map.cmj : bs_MapString.cmj bs_MapInt.cmj bs_MapDict.cmj bs_Id.cmj \
     bs_Array.cmj bs_Map.cmi
 bs_internalMapInt.cmj : bs_internalAVLtree.cmj bs_SortArray.cmj bs_Array.cmj
 bs_internalMapString.cmj : bs_internalAVLtree.cmj bs_SortArray.cmj \
@@ -56,17 +54,17 @@ bs_MapString.cmj : bs_internalMapString.cmj bs_internalAVLtree.cmj \
     bs_Array.cmj bs_MapString.cmi
 bs_MapInt.cmj : bs_internalMapInt.cmj bs_internalAVLtree.cmj bs_Array.cmj \
     bs_MapInt.cmi
-bs_Set.cmj : bs_SetString.cmj bs_SetInt.cmj bs_SetDict.cmj bs_Dict.cmj \
+bs_Set.cmj : bs_SetString.cmj bs_SetInt.cmj bs_SetDict.cmj bs_Id.cmj \
     bs_Array.cmj bs_Set.cmi
 bs_MutableSet.cmj : bs_internalAVLset.cmj bs_SortArray.cmj \
-    bs_MutableSetString.cmj bs_MutableSetInt.cmj bs_Dict.cmj bs_Array.cmj \
+    bs_MutableSetString.cmj bs_MutableSetInt.cmj bs_Id.cmj bs_Array.cmj \
     bs_MutableSet.cmi
 bs_MutableSetInt.cmj : bs_internalSetInt.cmj bs_internalAVLset.cmj \
     bs_SortArrayInt.cmj bs_Array.cmj
 bs_MutableSetString.cmj : bs_internalSetString.cmj bs_internalAVLset.cmj \
     bs_SortArrayString.cmj bs_Array.cmj bs_MutableSetString.cmi
 bs_MutableMap.cmj : bs_internalAVLtree.cmj bs_MutableMapString.cmj \
-    bs_MutableMapInt.cmj bs_Dict.cmj bs_Array.cmj bs_MutableMap.cmi
+    bs_MutableMapInt.cmj bs_Id.cmj bs_Array.cmj bs_MutableMap.cmi
 bs_MutableMapInt.cmj : bs_internalMapInt.cmj bs_internalAVLtree.cmj \
     bs_Array.cmj bs_MutableMapInt.cmi
 bs_MutableMapString.cmj : bs_internalMapString.cmj bs_internalAVLtree.cmj \
@@ -104,8 +102,8 @@ js_option.cmi :
 js_result.cmi :
 js_mapperRt.cmi :
 bs_Array.cmi :
-bs_internalAVLset.cmi : bs_Dict.cmi
-bs_internalAVLtree.cmi : bs_Dict.cmi
+bs_internalAVLset.cmi : bs_Id.cmi
+bs_internalAVLtree.cmi : bs_Id.cmi
 bs_List.cmi :
 bs_SortArray.cmi : bs_SortArrayString.cmi bs_SortArrayInt.cmi
 bs_SortArrayInt.cmi :
@@ -114,20 +112,20 @@ bs_Range.cmi :
 bs_internalBucketsType.cmi :
 bs_internalSetBuckets.cmi : bs_internalBucketsType.cmi
 bs_internalBuckets.cmi : bs_internalBucketsType.cmi
-bs_HashMap.cmi : bs_HashMapString.cmi bs_HashMapInt.cmi bs_Dict.cmi
-bs_HashSet.cmi : bs_HashSetString.cmi bs_HashSetInt.cmi bs_Dict.cmi
+bs_HashMap.cmi : bs_Id.cmi bs_HashMapString.cmi bs_HashMapInt.cmi
+bs_HashSet.cmi : bs_Id.cmi bs_HashSetString.cmi bs_HashSetInt.cmi
 bs_HashSetString.cmi :
 bs_HashSetInt.cmi :
-bs_Dict.cmi :
-bs_MapDict.cmi : bs_Dict.cmi
-bs_SetDict.cmi : bs_Dict.cmi
-bs_Map.cmi : bs_MapString.cmi bs_MapInt.cmi bs_MapDict.cmi bs_Dict.cmi
+bs_Id.cmi :
+bs_MapDict.cmi : bs_Id.cmi
+bs_SetDict.cmi : bs_Id.cmi
+bs_Map.cmi : bs_MapString.cmi bs_MapInt.cmi bs_MapDict.cmi bs_Id.cmi
 bs_MapString.cmi :
 bs_MapInt.cmi :
-bs_Set.cmi : bs_SetString.cmi bs_SetInt.cmi bs_SetDict.cmi bs_Dict.cmi
-bs_MutableSet.cmi : bs_MutableSetString.cmi bs_MutableSetInt.cmj bs_Dict.cmi
+bs_Set.cmi : bs_SetString.cmi bs_SetInt.cmi bs_SetDict.cmi bs_Id.cmi
+bs_MutableSet.cmi : bs_MutableSetString.cmi bs_MutableSetInt.cmj bs_Id.cmi
 bs_MutableSetString.cmi :
-bs_MutableMap.cmi : bs_MutableMapString.cmi bs_MutableMapInt.cmi bs_Dict.cmi
+bs_MutableMap.cmi : bs_MutableMapString.cmi bs_MutableMapInt.cmi bs_Id.cmi
 bs_MutableMapInt.cmi :
 bs_MutableMapString.cmi :
 bs_SetInt.cmi :
diff --git a/jscomp/others/Makefile b/jscomp/others/Makefile
index d055cdeec7..5041306530 100644
--- a/jscomp/others/Makefile
+++ b/jscomp/others/Makefile
@@ -26,7 +26,7 @@ SOURCE_LIST= node_path node_fs node_process dict node_module js_array js_string
 	bs_HashSet\
 	bs_HashSetString\
 	bs_HashSetInt\
-	bs_Dict\
+	bs_Id\
 	bs_MapDict\
 	bs_SetDict\
 	bs_Map\
diff --git a/jscomp/others/bs.ml b/jscomp/others/bs.ml
index c89a4f60ee..3f1ef7cd08 100644
--- a/jscomp/others/bs.ml
+++ b/jscomp/others/bs.ml
@@ -25,7 +25,7 @@
 
 (** A stdlib shipped with BuckleScript 
 
-    This stdlib is still in  beta status, but we encourage you to try it out and 
+    This stdlib is still in {i beta} status, but we encourage you to try it out and 
     provide feedback.
 
     {b Motivation }
@@ -70,29 +70,30 @@
     {[
       type t = int * int 
       module I0 =
-        (val Bs.Dict.comparableU ~cmp:(fun[\@bs] ((a0,a1) : t) ((b0,b1) : t) ->
+        (val Bs.Id.comparableU ~cmp:(fun[\@bs] ((a0,a1) : t) ((b0,b1) : t) ->
              match compare a0 b0 with
              | 0 -> compare a1 b1
              | c -> c 
            ))
-    let s0 = Bs.Set.make (module I0)
+    let s0 = Bs.Set.make ~id:(module I0)
     module I1 =
-      (val Bs.Dict.comparableU ~cmp:(fun[\@bs] ((a0,a1) : t) ((b0,b1) : t) ->
+      (val Bs.Id.comparableU ~cmp:(fun[\@bs] ((a0,a1) : t) ((b0,b1) : t) ->
            match compare a1 b1 with
            | 0 -> compare a0 b0
            | c -> c 
          ))
-    let s1 = Bs.Set.make (module I1)
+    let s1 = Bs.Set.make ~id:(module I1)
     ]}
 
     Here the compiler would infer [s0] and [s1] having different type so that
     it would not mix.
 
     {[
-      val s0 : Bs.Set.t ((int * int), I0.id)
-      val s1 : Bs.Set.t ((int * int), I1.id)
+      val s0 : Bs.Set.t ((int * int), I0.identity)
+      val s1 : Bs.Set.t ((int * int), I1.identity)
     ]}
 
+    [I0.identity] and [I1.identity] are not the same using our encoding scheme.
 
     {b Collection Hierachy}
 
@@ -115,7 +116,7 @@
     
 *)
 
-(** {!Bs.Dict}
+(** {!Bs.Id}
 
     Provide utiliites to create identified comparators or hashes for 
     data structures used below. 
@@ -124,7 +125,7 @@
     functions so that different data structures with slightly different 
     comparison functions won't mix
 *)
-module Dict = Bs_Dict
+module Id = Bs_Id
 
 (** {!Bs.Array}
 
diff --git a/jscomp/others/bs_Array.ml b/jscomp/others/bs_Array.ml
index 770f4d7f70..e15235a2f1 100644
--- a/jscomp/others/bs_Array.ml
+++ b/jscomp/others/bs_Array.ml
@@ -108,7 +108,29 @@ let makeByAndShuffleU l f =
 
 let makeByAndShuffle l f = makeByAndShuffleU l (fun[@bs] a -> f a)
 
+let range start finish =
+  let cut = finish - start in 
+  if cut < 0  then [||]
+  else
+    let arr = makeUninitializedUnsafe (cut + 1 ) in
+    for i = 0 to cut do
+      setUnsafe arr i (start + i)
+    done;
+    arr
 
+let rangeBy start finish ~step =
+  let cut = finish - start in
+  if cut < 0 || step <=0 then
+    [||]
+  else
+    let nb = cut/step + 1 in
+    let arr = makeUninitializedUnsafe  nb in
+    let cur = ref start in 
+    for i = 0 to nb - 1 do
+      setUnsafe arr i !cur;
+      cur := !cur + step ; 
+    done;
+    arr 
 
 let zip xs ys = 
   let lenx, leny = length xs, length ys in 
diff --git a/jscomp/others/bs_Array.mli b/jscomp/others/bs_Array.mli
index 09b2e778f4..89b057e309 100644
--- a/jscomp/others/bs_Array.mli
+++ b/jscomp/others/bs_Array.mli
@@ -86,6 +86,31 @@ val make: int -> 'a  -> 'a array
     @return an empty array when [n] is negative.
 *)
 
+val range: int -> int -> int array
+(** [range start finish] create an inclusive array
+    @example {[
+      range 0 3 =  [|0;1;2;3|];;
+      range 3 0 =  [||] ;;
+      range 3 3 = [|3|];;
+    ]}
+*)
+val rangeBy: int -> int -> step:int -> int array
+(** [rangeBy start finish ~step]
+
+    @return empty array when step is 0 or negative
+    it also return empty array when [start > finish]
+    
+    @example {[
+     rangeBy 0 10 ~step:3 = [|0;3;6;9|];;
+     rangeBy 0 12 ~step:3 = [|0;3;6;9;12|];;
+     rangeBy 33 0 ~step:1 =  [||];;
+     rangeBy 33 0 ~step:(-1) = [||];;
+     rangeBy 3 12 ~step:(-1) = [||];;
+     rangeBy 3 3 ~step:0 = [||] ;;     
+     rangeBy 3 3 ~step:(1) = [|3|] ;;
+   ]}
+*)    
+
 val makeByU: int -> (int -> 'a [@bs]) -> 'a array
 val makeBy: int -> (int -> 'a ) -> 'a array
 (** [makeBy n f] 
diff --git a/jscomp/others/bs_Bag.ml b/jscomp/others/bs_Bag.ml
deleted file mode 100644
index c7d97a6127..0000000000
--- a/jscomp/others/bs_Bag.ml
+++ /dev/null
@@ -1,36 +0,0 @@
-(* Copyright (C) 2017 Authors of BuckleScript
- * 
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- * 
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
-
-type (+ 'k, + 'v) bag = {
-  dict : 'k ;
-  data : 'v
-} [@@bs.deriving abstract]
-
-(* without variance annotation
-
-  {[
-    let m = N.empty (module N)
-  ]}
-  will not be allowed if m is polymoprhic
-*)
diff --git a/jscomp/others/bs_BagM.ml b/jscomp/others/bs_BagM.ml
deleted file mode 100644
index 24511b8acc..0000000000
--- a/jscomp/others/bs_BagM.ml
+++ /dev/null
@@ -1,6 +0,0 @@
-
-
-type (+ 'k, 'v ) bag = {
-  dict : 'k;
-  mutable data : 'v;
-} [@@bs.deriving abstract]
\ No newline at end of file
diff --git a/jscomp/others/bs_HashMap.ml b/jscomp/others/bs_HashMap.ml
index 499fbef763..761d9f58f8 100644
--- a/jscomp/others/bs_HashMap.ml
+++ b/jscomp/others/bs_HashMap.ml
@@ -17,9 +17,9 @@ module C = Bs_internalBucketsType
 module A = Bs_Array
 
 
-type ('a, 'id) eq = ('a, 'id) Bs_Dict.eq
-type ('a, 'id) hash = ('a, 'id) Bs_Dict.hash
-type ('a, 'id) dict = ('a, 'id) Bs_Dict.hashable
+type ('a, 'id) eq = ('a, 'id) Bs_Id.eq
+type ('a, 'id) hash = ('a, 'id) Bs_Id.hash
+type ('a, 'id) dict = ('a, 'id) Bs_Id.hashable
 type ('a,'b,'id) t =
   ( ('a, 'id) hash, ('a, 'id) eq, 'a, 'b) N.t
 
@@ -110,8 +110,8 @@ let set0 h key value ~eq ~hash =
 *)      
 let set  h key value =
   set0 h key value
-   ~eq:(Bs_Dict.getEqInternal (C.eq h))
-   ~hash:(Bs_Dict.getHashInternal (C.hash h))
+   ~eq:(Bs_Id.getEqInternal (C.eq h))
+   ~hash:(Bs_Id.getHashInternal (C.hash h))
 
 let rec removeInBucket  h h_buckets  i key prec bucket ~eq =
   match C.toOpt bucket with
@@ -129,12 +129,12 @@ let rec removeInBucket  h h_buckets  i key prec bucket ~eq =
 
 let remove h key = 
   let h_buckets = C.buckets h in 
-  let i = (Bs_Dict.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in  
+  let i = (Bs_Id.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in  
   let bucket = A.getUnsafe h_buckets i in 
   match C.toOpt bucket with 
   | None -> ()
   | Some cell -> 
-    let eq = (Bs_Dict.getEqInternal (C.eq h)) in 
+    let eq = (Bs_Id.getEqInternal (C.eq h)) in 
     if eq (N.key cell ) key [@bs] then 
     begin 
       A.setUnsafe h_buckets i (N.next cell);
@@ -154,11 +154,11 @@ let rec getAux ~eq key buckets =
 
 let get h key =
   let h_buckets = C.buckets h in 
-  let nid = (Bs_Dict.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in 
+  let nid = (Bs_Id.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in 
   match C.toOpt @@ A.getUnsafe h_buckets nid with
   | None -> None
   | Some cell1  ->
-    let eq = Bs_Dict.getEqInternal (C.eq h) in
+    let eq = Bs_Id.getEqInternal (C.eq h) in
     if eq key (N.key cell1) [@bs] then 
       Some  (N.value cell1)
     else
@@ -185,12 +185,12 @@ let rec memInBucket key cell ~eq =
 
 let has h key =
   let h_buckets = C.buckets h in 
-  let nid = (Bs_Dict.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in 
+  let nid = (Bs_Id.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in 
   let bucket = A.getUnsafe h_buckets nid in 
   match C.toOpt bucket with 
   | None -> false 
   | Some bucket -> 
-    memInBucket ~eq:(Bs_Dict.getEqInternal (C.eq h)) key bucket
+    memInBucket ~eq:(Bs_Id.getEqInternal (C.eq h)) key bucket
 
 
 
@@ -205,7 +205,7 @@ let ofArray (type a) (type id) arr ~dict:(dict:(a,id) dict) =
   let hash, eq = M.hash, M.eq in  
   let len = A.length arr in 
   let v = C.make ~hash ~eq len in 
-  let eq, hash = Bs_Dict.getEqInternal eq, Bs_Dict.getHashInternal hash in   
+  let eq, hash = Bs_Id.getEqInternal eq, Bs_Id.getHashInternal hash in   
   for i = 0 to len - 1 do 
     let key,value = (A.getUnsafe arr i) in 
     set0 ~eq ~hash v key value
@@ -213,7 +213,7 @@ let ofArray (type a) (type id) arr ~dict:(dict:(a,id) dict) =
   v
       
 let mergeMany h arr = 
-  let hash, eq = Bs_Dict.getHashInternal ( C.hash h) , Bs_Dict.getEqInternal (C.eq h) in 
+  let hash, eq = Bs_Id.getHashInternal ( C.hash h) , Bs_Id.getEqInternal (C.eq h) in 
   let len = A.length arr in 
   for i = 0 to len - 1 do 
     let key,value = (A.getUnsafe arr i) in 
diff --git a/jscomp/others/bs_HashMap.mli b/jscomp/others/bs_HashMap.mli
index 606d30cc14..ea3f913a7d 100644
--- a/jscomp/others/bs_HashMap.mli
+++ b/jscomp/others/bs_HashMap.mli
@@ -28,7 +28,7 @@
 type ('key,'value,'id) t 
 (** The type of hash tables from type ['key] to type ['value]. *)
 
-type ('a, 'id) dict = ('a, 'id) Bs_Dict.hashable
+type ('a, 'id) dict = ('a, 'id) Bs_Id.hashable
 
 
 val make:  int -> dict:('key, 'id) dict -> ('key,'value,'id) t
diff --git a/jscomp/others/bs_HashSet.ml b/jscomp/others/bs_HashSet.ml
index a5712a4a97..3716b4fb16 100644
--- a/jscomp/others/bs_HashSet.ml
+++ b/jscomp/others/bs_HashSet.ml
@@ -31,9 +31,9 @@ module N = Bs_internalSetBuckets
 module C = Bs_internalBucketsType
 module A = Bs_Array
 
-type ('a, 'id) eq = ('a, 'id) Bs_Dict.eq
-type ('a, 'id) hash = ('a, 'id) Bs_Dict.hash
-type ('a, 'id) dict = ('a, 'id) Bs_Dict.hashable
+type ('a, 'id) eq = ('a, 'id) Bs_Id.eq
+type ('a, 'id) hash = ('a, 'id) Bs_Id.hash
+type ('a, 'id) dict = ('a, 'id) Bs_Id.hashable
 
 type ('a,'id) t =  ( ('a, 'id) hash, ('a, 'id) eq, 'a) N.t
 
@@ -43,7 +43,7 @@ let rec copyBucket ~hash ~h_buckets ~ndata_tail  old_bucket =
   match C.toOpt old_bucket with 
   | None -> ()
   | Some cell ->
-    let nidx = (Bs_Dict.getHashInternal hash) (N.key cell) [@bs] land (A.length h_buckets - 1) in 
+    let nidx = (Bs_Id.getHashInternal hash) (N.key cell) [@bs] land (A.length h_buckets - 1) in 
     let v = C.return cell in 
     begin match C.toOpt (A.getUnsafe ndata_tail nidx) with
       | None -> 
@@ -77,7 +77,7 @@ let tryDoubleResize ~hash h =
 
 let rec removeBucket ~eq h h_buckets  i key prec cell =
   let cell_next = N.next cell in 
-  if (Bs_Dict.getEqInternal eq) (N.key cell) key [@bs]
+  if (Bs_Id.getEqInternal eq) (N.key cell) key [@bs]
   then 
     begin
       N.nextSet prec cell_next;
@@ -93,13 +93,13 @@ let rec removeBucket ~eq h h_buckets  i key prec cell =
 let remove h key = 
   let eq = C.eq h in 
   let h_buckets = C.buckets h in 
-  let i = (Bs_Dict.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in  
+  let i = (Bs_Id.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in  
   let l = A.getUnsafe h_buckets i in 
   match C.toOpt l with 
   | None -> ()
   | Some cell -> 
     let next_cell = N.next cell in 
-    if (Bs_Dict.getEqInternal eq) (N.key cell) key [@bs] then 
+    if (Bs_Id.getEqInternal eq) (N.key cell) key [@bs] then 
       begin 
         C.sizeSet h (C.size h - 1) ;
         A.setUnsafe h_buckets i next_cell
@@ -113,7 +113,7 @@ let remove h key =
 
 
 let rec addBucket h key  cell  ~eq = 
-  if not ((Bs_Dict.getEqInternal eq) (N.key cell) key [@bs]) then
+  if not ((Bs_Id.getEqInternal eq) (N.key cell) key [@bs]) then
     let  n = N.next cell in 
     match C.toOpt n with 
     | None ->  
@@ -124,7 +124,7 @@ let rec addBucket h key  cell  ~eq =
 let add0 h key  ~hash  ~eq =
   let h_buckets = C.buckets h in 
   let buckets_len = A.length h_buckets in 
-  let i = (Bs_Dict.getHashInternal hash) key [@bs] land (buckets_len - 1) in 
+  let i = (Bs_Id.getHashInternal hash) key [@bs] land (buckets_len - 1) in 
   let l = A.getUnsafe h_buckets i in  
   (match C.toOpt l with                                    
    | None -> 
@@ -139,7 +139,7 @@ let add h key  =
   add0 ~hash:(C.hash h) ~eq:(C.eq h) h  key 
 
 let rec memInBucket ~eq key cell = 
-  (Bs_Dict.getEqInternal eq) 
+  (Bs_Id.getEqInternal eq) 
     (N.key cell) key [@bs] || 
   (match C.toOpt (N.next cell) with 
    | None -> false 
@@ -150,7 +150,7 @@ let rec memInBucket ~eq key cell =
   
 let has h key =           
   let eq, h_buckets = C.eq h, C.buckets h  in 
-  let nid = (Bs_Dict.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in 
+  let nid = (Bs_Id.getHashInternal (C.hash h)) key [@bs] land (A.length h_buckets - 1) in 
   let bucket = A.getUnsafe h_buckets nid in 
   match C.toOpt bucket with 
   | None -> false 
diff --git a/jscomp/others/bs_HashSet.mli b/jscomp/others/bs_HashSet.mli
index c042eaee1f..bbb92b5b55 100644
--- a/jscomp/others/bs_HashSet.mli
+++ b/jscomp/others/bs_HashSet.mli
@@ -34,7 +34,7 @@ type ('a, 'id) t
 
 (** The type of hash tables from type ['a] to type ['b]. *)
 
-type ('a, 'id) dict = ('a, 'id) Bs_Dict.hashable
+type ('a, 'id) dict = ('a, 'id) Bs_Id.hashable
 
 val make:  int -> dict:('a,'id) dict ->  ('a, 'id) t
 val clear: ('a, 'id) t -> unit
diff --git a/jscomp/others/bs_Dict.ml b/jscomp/others/bs_Id.ml
similarity index 91%
rename from jscomp/others/bs_Dict.ml
rename to jscomp/others/bs_Id.ml
index dffde48cb6..993fbc3cae 100644
--- a/jscomp/others/bs_Dict.ml
+++ b/jscomp/others/bs_Id.ml
@@ -34,13 +34,13 @@ external getCmpInternal : ('a,'id) cmp -> ('a -> 'a -> int [@bs]) = "%identity"
 
 
 module type Comparable = sig
-  type id
+  type identity
   type t
-  val cmp: (t, id) cmp
+  val cmp: (t, identity) cmp
 end
 
 type ('key, 'id) comparable =
-  (module Comparable with type t = 'key and type id = 'id)
+  (module Comparable with type t = 'key and type identity = 'id)
 
 
 module MakeComparable (M : sig
@@ -48,7 +48,7 @@ module MakeComparable (M : sig
    val cmp: t -> t -> int [@bs]
   end) =
 struct
-  type id
+  type identity
   type t = M.t
   let cmp = M.cmp
 end
@@ -68,13 +68,13 @@ let comparable ~cmp =
   comparableU ~cmp:(fun[@bs] a b -> cmp a b)
     
 module type Hashable = sig 
-  type id 
+  type identity 
   type t 
-  val hash: (t,id) hash
-  val eq:  (t,id) eq
+  val hash: (t,identity) hash
+  val eq:  (t,identity) eq
 end
 
-type ('key, 'id) hashable = (module Hashable with type t = 'key and type id = 'id)
+type ('key, 'id) hashable = (module Hashable with type t = 'key and type identity = 'id)
                             
 module MakeHashable (M : sig
    type t
@@ -82,7 +82,7 @@ module MakeHashable (M : sig
    val eq : t -> t -> bool [@bs]
   end) =
 struct
-  type id
+  type identity
   type t = M.t
   let hash = M.hash
   let eq = M.eq
diff --git a/jscomp/others/bs_Dict.mli b/jscomp/others/bs_Id.mli
similarity index 93%
rename from jscomp/others/bs_Dict.mli
rename to jscomp/others/bs_Id.mli
index fbfb310ec4..66d0971228 100644
--- a/jscomp/others/bs_Dict.mli
+++ b/jscomp/others/bs_Id.mli
@@ -24,7 +24,7 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 
-(** {!Bs.Dict}
+(** {!Bs.Id}
     
     Provide utiliites to create identified comparators or hashes for 
     data structures used below. 
@@ -57,13 +57,13 @@ type ('a, 'id) cmp
 *)
     
 module type Comparable = sig
-  type id
+  type identity
   type t
-  val cmp: (t, id) cmp
+  val cmp: (t, identity) cmp
 end
 
 type ('key, 'id) comparable =
-  (module Comparable with type t = 'key and type id = 'id)
+  (module Comparable with type t = 'key and type identity = 'id)
 (** [('key, 'id) cmparable] is a module of functions, here it only includes [cmp].
 
     Unlike normal functions, when created, it comes with a unique identity (guaranteed
@@ -84,14 +84,14 @@ val comparable:
   (module Comparable with type t = 'a)
   
 module type Hashable = sig 
-  type id 
+  type identity 
   type t 
-  val hash: (t,id) hash
-  val eq:  (t,id) eq
+  val hash: (t,identity) hash
+  val eq:  (t,identity) eq
 end 
 
 type ('key, 'id) hashable =
-  (module Hashable with type t = 'key and type id = 'id)
+  (module Hashable with type t = 'key and type identity = 'id)
 (** [('key, 'id) hashable] is a module of functions, here it only includes [hash], [eq].
     
     Unlike normal functions, when created, it comes with a unique identity (guaranteed
diff --git a/jscomp/others/bs_List.mli b/jscomp/others/bs_List.mli
index 75a2774281..1a25c3bace 100644
--- a/jscomp/others/bs_List.mli
+++ b/jscomp/others/bs_List.mli
@@ -192,7 +192,7 @@ val mapReverse2U: 'a t -> 'b t -> ('a -> 'b -> 'c [@bs]) -> 'c t
 val mapReverse2: 'a t -> 'b t -> ('a -> 'b -> 'c) -> 'c t
 (** [mapReverse2 xs ys f]
 
-    equivalent to [reverse (map2 xs ys f)]    
+    equivalent to [reverse (zipBy xs ys f)]    
 
     @example {[
       mapReverse2 [1;2;3] [1;2] (+) = [4;2]
diff --git a/jscomp/others/bs_Map.ml b/jscomp/others/bs_Map.ml
index 2a626cab96..1b01a321d0 100644
--- a/jscomp/others/bs_Map.ml
+++ b/jscomp/others/bs_Map.ml
@@ -9,8 +9,8 @@
 (*  under the terms of the GNU Library General Public License, with    *)
 (*  the special exception on linking described in file ../LICENSE.     *)
 (*                                                                     *)
+(*  Adapted by authors of BuckleScript without using functors          *)
 (***********************************************************************)
-(** Adapted by authors of BuckleScript without using functors          *)
 
 (** specalized when key type is [int], more efficient
     than the gerneic type
@@ -28,8 +28,8 @@ module Dict = Bs_MapDict
 module N = Bs_MapDict
 module A = Bs_Array
 
-type ('key, 'id ) dict = ('key, 'id) Bs_Dict.comparable
-type ('key, 'id ) cmp = ('key, 'id) Bs_Dict.cmp
+type ('key, 'id ) id = ('key, 'id) Bs_Id.comparable
+type ('key, 'id ) cmp = ('key, 'id) Bs_Id.cmp
 module S = struct 
   type ('k,'v,'id) t = {
     cmp: ('k,'id) cmp;
@@ -40,8 +40,8 @@ end
 
 type ('k, 'v, 'id ) t = ('k, 'v, 'id) S.t 
 
-let ofArray (type k) (type id) data ~(dict : (k,id) dict)  =
-  let module M = (val dict) in
+let ofArray (type k) (type idx) data ~(id : (k,idx) id)  =
+  let module M = (val id) in
   let cmp = M.cmp in 
   S.t ~cmp ~data:(Dict.ofArray ~cmp data) 
 
@@ -81,8 +81,8 @@ let mergeU s1 s2 f =
 let merge s1 s2 f = 
   mergeU s1 s2 (fun [@bs] a b c -> f a b c)
 
-let make (type elt) (type id) ~(dict: (elt, id) dict) =
-  let module M = (val dict) in 
+let make (type elt) (type idx) ~(id: (elt, idx) id) =
+  let module M = (val id) in 
   S.t  ~cmp:M.cmp  ~data:Dict.empty
 
 let isEmpty map = 
@@ -155,15 +155,15 @@ let cmp m1 m2 vcmp = cmpU m1 m2 (fun [@bs] a b -> vcmp a b)
     
 let getData = S.data
   
-let getDict (type elt) (type id) (m : (elt,_,id) t) : (elt, id) dict =
+let getId (type elt) (type identity) (m : (elt,_,identity) t) : (elt, identity) id =
   let module T = struct
-    type nonrec id = id
+    type nonrec identity = identity
     type nonrec t = elt
     let cmp =  S.cmp m
   end in
   (module T )
   
-let packDictData (type elt) (type id) ~(dict : (elt, id) dict) ~data  =
-  let module M = (val dict) in 
+let packIdData (type elt) (type idx) ~(id : (elt, idx) id) ~data  =
+  let module M = (val id) in 
   S.t ~cmp:M.cmp ~data
 
diff --git a/jscomp/others/bs_Map.mli b/jscomp/others/bs_Map.mli
index 07e2ac7b39..7dca36992a 100644
--- a/jscomp/others/bs_Map.mli
+++ b/jscomp/others/bs_Map.mli
@@ -9,11 +9,10 @@
 (*  under the terms of the GNU Library General Public License, with    *)
 (*  the special exception on linking described in file ../LICENSE.     *)
 (*                                                                     *)
+(*  Adapted by authors of BuckleScript without using functors          *)
 (***********************************************************************)
-(** Adapted by authors of BuckleScript without using functors          *)
 
-
-(** specalized when key type is [int], more efficient
+(** Specalized when key type is [int], more efficient
     than the gerneic type
 *)
 module Int = Bs_MapInt
@@ -21,7 +20,7 @@ module Int = Bs_MapInt
     than the gerneic type *)  
 module String = Bs_MapString
 
-(** seprate function from data, a more verbsoe but slightly
+(** Seprate function from data, a more verbsoe but slightly
     more efficient
 *)  
 module Dict = Bs_MapDict
@@ -29,32 +28,32 @@ module Dict = Bs_MapDict
 
 type ('k,'v,'id) t
 
-type ('key, 'id ) dict = ('key, 'id) Bs_Dict.comparable
+type ('key, 'id ) id = ('key, 'id) Bs_Id.comparable
 (** The data associated with a comparison function *)   
 
 (*
     How we retain soundness:
     The only way to create a value of type [_ t] from scratch 
-    is through [empty] which requires [_ Bs_Dict.t]
-    The only way to create [_ Bs_Dict.t] is using [Bs_Dict.Make] which
+    is through [empty] which requires [_ Bs_Id.t]
+    The only way to create [_ Bs_Id.t] is using [Bs_Id.Make] which
     will create a fresh type [id] per module
 
     Generic operations over tree without [cmp] are still exported 
     (for efficient reasons) so that [data] does not need be boxed and unboxed.
 
     The soundness is guaranteed in two aspects:
-    When create a value of [_ t] it needs both [_ Bs_Dict.t] and [_ t0].
-    [_ Bs_Dict.t] is an abstract type. Note [add0] requires [_ Bs_Dict.cmp] which 
-    is also an abstract type which can only come from [_ Bs_Dict.t]
+    When create a value of [_ t] it needs both [_ Bs_Id.t] and [_ t0].
+    [_ Bs_Id.t] is an abstract type. Note [add0] requires [_ Bs_Id.cmp] which 
+    is also an abstract type which can only come from [_ Bs_Id.t]
 
     When destructing a value of [_ t], the ['id] parameter is threaded.
 
 *)
 
-(* should not export [Bs_Dict.compare]. 
-   should only export [Bs_Dict.t] or [Bs_Dict.cmp] instead *)
+(* should not export [Bs_Id.compare]. 
+   should only export [Bs_Id.t] or [Bs_Id.cmp] instead *)
 
-val make: dict:('k, 'id) dict -> ('k, 'a, 'id) t 
+val make: id:('k, 'id) id -> ('k, 'a, 'id) t 
 val isEmpty: _ t -> bool
 
 val has: ('k, 'a, 'id) t -> 'k  -> bool    
@@ -112,7 +111,7 @@ val size: ('k, 'a, 'id) t -> int
 val toList: ('k, 'a, 'id) t -> ('k * 'a) list
 (** In increasing order*)
 val toArray: ('k, 'a, 'id) t -> ('k * 'a) array
-val ofArray:  ('k * 'a) array -> dict:('k,'id) dict -> ('k,'a,'id) t         
+val ofArray:  ('k * 'a) array -> id:('k,'id) id -> ('k,'a,'id) t         
 val keysToArray: ('k, 'a, 'id) t -> 'k  array
 val valuesToArray: ('k, 'a, 'id) t -> 'a  array
 val minKey: ('k, _, _) t -> 'k option
@@ -213,9 +212,9 @@ val map: ('k, 'a, 'id) t -> ('a -> 'b) ->  ('k ,'b,'id ) t
 val mapWithKeyU: ('k, 'a, 'id) t -> ('k -> 'a -> 'b [@bs]) -> ('k, 'b, 'id) t
 val mapWithKey: ('k, 'a, 'id) t -> ('k -> 'a -> 'b) -> ('k, 'b, 'id) t
 
-val getDict: ('a, 'b, 'c) t -> ('a, 'c) dict
+val getId: ('a, 'b, 'c) t -> ('a, 'c) id
 
 val getData: ('a, 'b, 'c) t -> ('a, 'b, 'c) Bs_MapDict.t
     
-val packDictData: dict:('a, 'b) dict -> data:('a, 'c, 'b) Bs_MapDict.t -> ('a, 'c, 'b) t
+val packIdData: id:('a, 'b) id -> data:('a, 'c, 'b) Bs_MapDict.t -> ('a, 'c, 'b) t
 
diff --git a/jscomp/others/bs_MapDict.ml b/jscomp/others/bs_MapDict.ml
index fb3449d465..e5a21c7634 100644
--- a/jscomp/others/bs_MapDict.ml
+++ b/jscomp/others/bs_MapDict.ml
@@ -27,7 +27,7 @@ module A = Bs_Array
 
 type ('key,  'a, 'id) t = ('key, 'a) N.t
 
-type ('key, 'id) cmp = ('key, 'id)  Bs_Dict.cmp
+type ('key, 'id) cmp = ('key, 'id)  Bs_Id.cmp
 
 let empty = N.empty
 let ofArray = N.ofArray
@@ -81,7 +81,7 @@ let rec set  (t : _ t) newK newD  ~cmp =
   | None -> N.singleton newK newD 
   | Some n  ->
     let k= N.key n in 
-    let c = (Bs_Dict.getCmpInternal cmp) newK k [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) newK k [@bs] in
     if c = 0 then
       N.return (N.updateValue n newD) 
     else 
@@ -100,7 +100,7 @@ let rec updateU  (t : _ t) newK f  ~cmp :  _ t =
     end 
   | Some n  ->
     let k= N.key n in 
-    let c = (Bs_Dict.getCmpInternal cmp) newK k [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) newK k [@bs] in
     if c = 0 then
       match f (Some (N.value n)) [@bs] with 
       | None ->
@@ -148,7 +148,7 @@ let update t newK f ~cmp =
 
 let rec removeAux0  n x ~cmp = 
   let l,v,r = N.(left n, key n, right n ) in 
-  let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+  let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
   if c = 0 then
     match N.toOpt l, N.toOpt r with 
     | None, _ -> r 
@@ -189,7 +189,7 @@ let mergeMany   h arr ~cmp =
 
 let rec splitAuxPivot n x pres  ~cmp =  
   let l,v,d,r = N.(left n , key n, value n, right n) in  
-  let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in 
+  let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in 
   if c = 0 then begin 
     pres := Some d; 
     (l,  r)
diff --git a/jscomp/others/bs_MapDict.mli b/jscomp/others/bs_MapDict.mli
index 567d17029a..863c6a09ef 100644
--- a/jscomp/others/bs_MapDict.mli
+++ b/jscomp/others/bs_MapDict.mli
@@ -24,7 +24,7 @@
 
 type ('key,  'value, 'id) t
 
-type ('key, 'id) cmp = ('key, 'id) Bs_Dict.cmp
+type ('key, 'id) cmp = ('key, 'id) Bs_Id.cmp
 
 val empty: ('k, 'v, 'id) t
 
diff --git a/jscomp/others/bs_MutableMap.ml b/jscomp/others/bs_MutableMap.ml
index 628145df14..8e9bf3685e 100644
--- a/jscomp/others/bs_MutableMap.ml
+++ b/jscomp/others/bs_MutableMap.ml
@@ -30,8 +30,8 @@ module N = Bs_internalAVLtree
 module A = Bs_Array
 
 
-type ('key, 'id) dict = ('key, 'id) Bs_Dict.comparable
-type ('key, 'id ) cmp = ('key, 'id) Bs_Dict.cmp
+type ('key, 'id) dict = ('key, 'id) Bs_Id.comparable
+type ('key, 'id ) cmp = ('key, 'id) Bs_Id.cmp
     
 module S = struct    
   type ('k, 'v, 'id) t = {
@@ -44,7 +44,7 @@ type ('k, 'v, 'id) t = ('k, 'v, 'id) S.t
 
 let rec removeMutateAux nt x ~cmp = 
   let k = N.key nt in 
-  let c = (Bs_Dict.getCmpInternal cmp) x k [@bs] in 
+  let c = (Bs_Id.getCmpInternal cmp) x k [@bs] in 
   if c = 0 then 
     let l,r = N.(left nt, right nt) in       
     match N.(toOpt l, toOpt r) with 
@@ -108,7 +108,7 @@ let rec updateDone t x   f  ~cmp =
     | None -> t)
   | Some nt -> 
     let k = N.key nt in 
-    let  c = (Bs_Dict.getCmpInternal cmp) x k [@bs] in  
+    let  c = (Bs_Id.getCmpInternal cmp) x k [@bs] in  
     if c = 0 then begin     
       match f (Some (N.value nt)) [@bs] with
       | None ->
diff --git a/jscomp/others/bs_MutableMap.mli b/jscomp/others/bs_MutableMap.mli
index 6017d23223..97b024449d 100644
--- a/jscomp/others/bs_MutableMap.mli
+++ b/jscomp/others/bs_MutableMap.mli
@@ -29,7 +29,7 @@ module String = Bs_MutableMapString
 
 
 type ('k,'v,'id) t
-type ('key, 'id) dict = ('key, 'id) Bs_Dict.comparable
+type ('key, 'id) dict = ('key, 'id) Bs_Id.comparable
     
 val make: dict:('k, 'id) dict -> ('k, 'a, 'id) t
 val clear: _ t -> unit 
diff --git a/jscomp/others/bs_MutableSet.ml b/jscomp/others/bs_MutableSet.ml
index 0816d85561..3a8956e565 100644
--- a/jscomp/others/bs_MutableSet.ml
+++ b/jscomp/others/bs_MutableSet.ml
@@ -31,8 +31,8 @@ module A = Bs_Array
 module Sort = Bs_SortArray
 
 
-type ('k, 'id) dict = ('k, 'id) Bs_Dict.comparable
-type ('key, 'id ) cmp = ('key, 'id) Bs_Dict.cmp
+type ('k, 'id) dict = ('k, 'id) Bs_Id.comparable
+type ('key, 'id ) cmp = ('key, 'id) Bs_Id.cmp
 
 module S = struct
   type ('elt,'id) t =
@@ -77,7 +77,7 @@ let remove  d  v =
   match N.toOpt oldRoot with 
   | None -> ()
   | Some oldRoot2 ->
-    let newRoot = remove0 ~cmp:(Bs_Dict.getCmpInternal (S.cmp d)) oldRoot2 v in 
+    let newRoot = remove0 ~cmp:(Bs_Id.getCmpInternal (S.cmp d)) oldRoot2 v in 
     if newRoot != oldRoot then 
       S.dataSet d newRoot    
 
@@ -99,12 +99,12 @@ let removeMany d xs =
     let len = A.length xs in 
     S.dataSet d 
       (removeMany0 nt xs 0 len 
-        ~cmp:(Bs_Dict.getCmpInternal (S.cmp d)))
+        ~cmp:(Bs_Id.getCmpInternal (S.cmp d)))
 
 
 let rec removeCheck0  nt x removed ~cmp= 
   let k = N.key nt in 
-  let c = (Bs_Dict.getCmpInternal cmp) x k [@bs] in 
+  let c = (Bs_Id.getCmpInternal cmp) x k [@bs] in 
   if c = 0 then 
     let () = removed := true in  
     let l,r = N.(left nt, right nt) in       
@@ -167,7 +167,7 @@ let rec addCheck0  t x added ~cmp  =
 let addCheck m e = 
   let oldRoot = S.data m in 
   let added = ref false in 
-  let newRoot = addCheck0 ~cmp:(Bs_Dict.getCmpInternal (S.cmp m)) oldRoot e added in 
+  let newRoot = addCheck0 ~cmp:(Bs_Id.getCmpInternal (S.cmp m)) oldRoot e added in 
   if newRoot != oldRoot then 
     S.dataSet m newRoot;
   !added    
@@ -253,7 +253,7 @@ let getExn d x =
 let split d  key  =     
   let arr = N.toArray (S.data d) in
   let cmp = S.cmp d in 
-  let i = Sort.binarySearchByU arr key (Bs_Dict.getCmpInternal cmp)  in   
+  let i = Sort.binarySearchByU arr key (Bs_Id.getCmpInternal cmp)  in   
   let len = A.length arr in 
   if i < 0 then 
     let next = - i -1 in 
@@ -301,7 +301,7 @@ let intersect a b  : _ t =
     let tmp = A.makeUninitializedUnsafe totalSize in 
     ignore @@ N.fillArray dataa0 0 tmp ; 
     ignore @@ N.fillArray datab0 sizea tmp;
-    let p = Bs_Dict.getCmpInternal cmp in 
+    let p = Bs_Id.getCmpInternal cmp in 
     if (p (A.getUnsafe tmp (sizea - 1))
           (A.getUnsafe tmp sizea) [@bs] < 0)
        || 
@@ -330,7 +330,7 @@ let diff a b : _ t =
     let tmp = A.makeUninitializedUnsafe totalSize in 
     ignore @@ N.fillArray dataa0 0 tmp ; 
     ignore @@ N.fillArray datab0 sizea tmp;
-    let p = Bs_Dict.getCmpInternal cmp in 
+    let p = Bs_Id.getCmpInternal cmp in 
     if (p (A.getUnsafe tmp (sizea - 1))
           (A.getUnsafe tmp sizea) [@bs] < 0)
        || 
@@ -357,7 +357,7 @@ let union a b =
     let tmp = A.makeUninitializedUnsafe totalSize in 
     ignore @@ N.fillArray dataa0 0 tmp ;
     ignore @@ N.fillArray datab0 sizea tmp ;
-    let p = (Bs_Dict.getCmpInternal cmp)  in 
+    let p = (Bs_Id.getCmpInternal cmp)  in 
     if p
         (A.getUnsafe tmp (sizea - 1))
         (A.getUnsafe tmp sizea) [@bs] < 0 then 
diff --git a/jscomp/others/bs_MutableSet.mli b/jscomp/others/bs_MutableSet.mli
index da22e3d85f..37602f555c 100644
--- a/jscomp/others/bs_MutableSet.mli
+++ b/jscomp/others/bs_MutableSet.mli
@@ -34,7 +34,7 @@ module String = Bs_MutableSetString
 
 type ('k,'id) t 
 
-type ('k, 'id) dict = ('k, 'id) Bs_Dict.comparable
+type ('k, 'id) dict = ('k, 'id) Bs_Id.comparable
 
 val make: dict:('elt, 'id) dict -> ('elt, 'id) t
 
diff --git a/jscomp/others/bs_Range.ml b/jscomp/others/bs_Range.ml
index d773bb82de..31d7e3e1e4 100644
--- a/jscomp/others/bs_Range.ml
+++ b/jscomp/others/bs_Range.ml
@@ -40,12 +40,17 @@ let rec everyU s f p =
   
 let every s f p = everyU s f (fun [@bs] a -> p a)
     
-let rec everyByU s f ~step p =
+let rec everyByAux s f ~step p =
   if s > f then true
   else
     p s [@bs] &&
-    (everyByU (s + step) f ~step p )
-    
+    (everyByAux (s + step) f ~step p )
+
+let everyByU s f ~step p = 
+  if step > 0 then 
+     everyByAux s f ~step p
+  else true (* return empty range [true]*)  
+
 let everyBy s f ~step p = everyByU s f ~step (fun [@bs] a -> p a)
 
 let rec someU s f p =  
@@ -57,11 +62,15 @@ let rec someU s f p =
 
 let some s f p = someU s f (fun[@bs] a -> p a)
 
-let rec someByU s f ~step p =  
+let rec someByAux s f ~step p =  
   if s > f then false
   else
     p s [@bs] ||
-    (someByU (s + step) f ~step p )
+    (someByAux (s + step) f ~step p )
     
+let someByU s f ~step p = 
+    if step > 0 then 
+      someByAux s f ~step p 
+    else false  (* return empty range, [false] *) 
 
 let someBy s f ~step p = someByU s f ~step (fun[@bs] a -> p a)
diff --git a/jscomp/others/bs_Range.mli b/jscomp/others/bs_Range.mli
index 39fb443a5c..80a8d1fa72 100644
--- a/jscomp/others/bs_Range.mli
+++ b/jscomp/others/bs_Range.mli
@@ -23,17 +23,45 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
+(** A small module to provide a inclusive range operations [\[start, finsish\]],
+    it use a for-loop internally instead of creating an array
+*)
+
 val forEachU: int -> int -> (int -> unit [@bs]) -> unit
 val forEach: int -> int -> (int -> unit ) -> unit
+(** [forEach start finish action]
 
+    equivalent to [Bs.Array.(forEach (range start finish) action)]
+*)
+  
 val everyU: int -> int -> (int -> bool [@bs]) -> bool
 val every: int -> int -> (int -> bool ) -> bool
+(** [every start finish p]
 
+    equivalent to [Bs.Array.(every (range start finish) p )]
+*)
+  
 val everyByU: int -> int -> step:int -> (int -> bool [@bs]) -> bool
 val everyBy: int -> int -> step:int -> (int -> bool ) -> bool
+(** [everyBy start finish ~step p]
 
+    {b See} {!Bs_Array.rangeBy}
+    
+    equivalent to [Bs.Array.(every (rangeBy start finish ~step) p)]
+*)
+  
 val someU: int -> int -> (int -> bool [@bs]) -> bool
 val some: int -> int -> (int -> bool ) -> bool
+(** [some start finish p]
+
+    equivalent to [Bs.Array.(some (range start finish) p)]
+*)
 
 val someByU: int -> int -> step:int -> (int -> bool [@bs]) -> bool
 val someBy: int -> int -> step:int -> (int -> bool ) -> bool  
+(** [someBy start finish ~step  p]
+
+    {b See} {!Bs_Array.rangeBy}
+    
+    equivalent to [Bs.Array.(some (rangeBy start finish ~step) p)]
+*)
diff --git a/jscomp/others/bs_Set.ml b/jscomp/others/bs_Set.ml
index 3a5cf1a348..df61f53b6a 100644
--- a/jscomp/others/bs_Set.ml
+++ b/jscomp/others/bs_Set.ml
@@ -29,8 +29,8 @@ module Dict = Bs_SetDict
 module A = Bs_Array
 
 
-type ('key, 'id) dict = ('key, 'id) Bs_Dict.comparable
-type ('key, 'id ) cmp = ('key, 'id) Bs_Dict.cmp
+type ('key, 'id) dict = ('key, 'id) Bs_Id.comparable
+type ('key, 'id ) cmp = ('key, 'id) Bs_Id.cmp
 
 module S = struct 
   type ('k,'id) t = {
@@ -154,9 +154,9 @@ let ofSortedArrayUnsafe (type elt) (type id) xs ~(dict : (elt,id) dict ) =
 
 let getData = S.data
 
-let getDict (type elt) (type id) (m : (elt,id) t) : (elt, id) dict =
+let getDict (type elt) (type identity) (m : (elt,identity) t) : (elt, identity) dict =
   let module T = struct
-    type nonrec id = id
+    type nonrec identity = identity
     type nonrec t = elt
     let cmp =  S.cmp m
   end in
diff --git a/jscomp/others/bs_Set.mli b/jscomp/others/bs_Set.mli
index d1f998e23f..ace6d6bca8 100644
--- a/jscomp/others/bs_Set.mli
+++ b/jscomp/others/bs_Set.mli
@@ -38,7 +38,7 @@ module Dict = Bs_SetDict
 
 type ('k,'id) t
 
-type ('key, 'id) dict = ('key, 'id) Bs_Dict.comparable
+type ('key, 'id) dict = ('key, 'id) Bs_Id.comparable
     
 val make: dict:('elt, 'id) dict -> ('elt, 'id) t
 
diff --git a/jscomp/others/bs_SetDict.ml b/jscomp/others/bs_SetDict.ml
index 701078d95d..86ac201678 100644
--- a/jscomp/others/bs_SetDict.ml
+++ b/jscomp/others/bs_SetDict.ml
@@ -27,7 +27,7 @@ module A = Bs_Array
 
 type ('k,'id) t = 'k N.t
 
-type ('key, 'id) cmp = ('key, 'id)  Bs_Dict.cmp
+type ('key, 'id) cmp = ('key, 'id)  Bs_Id.cmp
 
 
 (* here we relies on reference transparence
@@ -39,7 +39,7 @@ let rec add  (t : _ t) x  ~cmp : _ t =
   | None -> N.singleton x 
   | Some nt ->
     let k = N.key nt in 
-    let c = (Bs_Dict.getCmpInternal cmp) x k [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x k [@bs] in
     if c = 0 then t
     else
       let l,r = N.(left nt, right nt) in 
@@ -57,7 +57,7 @@ let rec remove (t : _ t) x  ~cmp : _ t =
     None -> t
   | Some n  ->
     let l,v,r = N.(left n , key n, right n) in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     if c = 0 then 
       match N.toOpt l, N.toOpt r with 
       | (None, _) -> r 
@@ -96,7 +96,7 @@ let removeMany h arr ~cmp =
 
 let rec splitAuxNoPivot ~cmp (n : _ N.node) x : _ *  _ =   
   let l,v,r = N.(left n , key n, right n) in  
-  let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+  let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
   if c = 0 then l,r
   else 
   if c < 0 then
@@ -116,7 +116,7 @@ let rec splitAuxNoPivot ~cmp (n : _ N.node) x : _ *  _ =
 
 let rec splitAuxPivot ~cmp (n : _ N.node) x pres : _ *  _ =   
   let l,v,r = N.(left n , key n, right n) in  
-  let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+  let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
   if c = 0 then 
     begin
       pres := true;
diff --git a/jscomp/others/bs_SetDict.mli b/jscomp/others/bs_SetDict.mli
index 3dae907fe4..d5c9504633 100644
--- a/jscomp/others/bs_SetDict.mli
+++ b/jscomp/others/bs_SetDict.mli
@@ -24,7 +24,7 @@
 
 type ('key, 'id) t
 
-type ('key, 'id) cmp = ('key, 'id) Bs_Dict.cmp
+type ('key, 'id) cmp = ('key, 'id) Bs_Id.cmp
     
 val empty: ('elt, 'id) t
 
diff --git a/jscomp/others/bs_internalAVLset.ml b/jscomp/others/bs_internalAVLset.ml
index 9fa82e3fa4..882fa74735 100644
--- a/jscomp/others/bs_internalAVLset.ml
+++ b/jscomp/others/bs_internalAVLset.ml
@@ -41,7 +41,7 @@ external return : 'a -> 'a Js.null = "%identity"
 external empty : 'a Js.null = "#null"
 external unsafeCoerce : 'a Js.null -> 'a = "%identity"
 
-type ('a, 'b) cmp = ('a, 'b) Bs_Dict.cmp  
+type ('a, 'b) cmp = ('a, 'b) Bs_Id.cmp  
 
 (* Sets are represented by balanced binary trees (the heights of the
    children differ by at most 2 *)
@@ -474,14 +474,14 @@ let rec has   (t: _ t) x ~cmp =
   | None -> false
   | Some n ->
     let v = key n in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     c = 0 || has ~cmp (if c < 0 then left n else right n) x
 
 
 let rec compareAux e1 e2 ~cmp =
   match e1,e2 with 
   | h1::t1, h2::t2 ->
-    let c = (Bs_Dict.getCmpInternal cmp) (key h1) (key h2) [@bs] in 
+    let c = (Bs_Id.getCmpInternal cmp) (key h1) (key h2) [@bs] in 
     if c = 0 then
       compareAux ~cmp 
         (stackAllLeft  (right h1) t1)
@@ -507,7 +507,7 @@ let rec subset (s1 : _ t) (s2 : _ t) ~cmp  =
   | Some t1 , Some t2  ->
     let l1,v1,r1 = (left t1, key t1, right t1) in  
     let l2,v2,r2 = (left t2, key t2, right t2) in 
-    let c = (Bs_Dict.getCmpInternal cmp) v1 v2 [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) v1 v2 [@bs] in
     if c = 0 then
       subset ~cmp l1 l2 && subset ~cmp r1 r2
     else if c < 0 then
@@ -522,7 +522,7 @@ let rec get  (n : _ t) x ~cmp =
     None -> None
   | Some t (* Node(l, v, r, _) *) ->
     let v = key t in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     if c = 0 then Some v
     else get ~cmp  (if c < 0 then left t else right t) x
 
@@ -532,7 +532,7 @@ let rec getUndefined (n : _ t) x ~cmp  =
     None -> Js.Undefined.empty
   | Some t (* Node(l, v, r, _) *) ->
     let v = key t in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     if c = 0 then  Js.Undefined.return v
     else getUndefined ~cmp  (if c < 0 then left t else right t) x 
 
@@ -541,7 +541,7 @@ let rec getExn  (n : _ t) x ~cmp =
     None -> [%assert "getExn0"]
   | Some t (* Node(l, v, r, _) *) ->
     let v = key t in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     if c = 0 then  v
     else getExn ~cmp  (if c < 0 then left t else right t) x 
 
@@ -621,7 +621,7 @@ let rec addMutate ~cmp (t : _ t) x =
   | None -> singleton x 
   | Some nt -> 
     let k = key nt in 
-    let  c = (Bs_Dict.getCmpInternal cmp) x k [@bs] in  
+    let  c = (Bs_Id.getCmpInternal cmp) x k [@bs] in  
     if c = 0 then t 
     else
       let l, r = (left nt, right nt) in 
@@ -639,7 +639,7 @@ let ofArray  (xs : _ array) ~cmp =
   if len = 0 then empty
   else
     let next = ref (S.strictlySortedLengthU xs 
-      (fun [@bs] x y -> (Bs_Dict.getCmpInternal cmp) x y [@bs] < 0)) in     
+      (fun [@bs] x y -> (Bs_Id.getCmpInternal cmp) x y [@bs] < 0)) in     
     let result = 
       ref (if !next >= 0 then  
         ofSortedArrayAux xs 0 !next
diff --git a/jscomp/others/bs_internalAVLset.mli b/jscomp/others/bs_internalAVLset.mli
index 9503e3f1e0..a24f591586 100644
--- a/jscomp/others/bs_internalAVLset.mli
+++ b/jscomp/others/bs_internalAVLset.mli
@@ -37,7 +37,7 @@ and 'elt node  = private {
   h : int
 } [@@bs.deriving abstract]
 
-type ('a, 'b) cmp = ('a, 'b) Bs_Dict.cmp
+type ('a, 'b) cmp = ('a, 'b) Bs_Id.cmp
 (* TODO: node is used in [subset] *)
 external toOpt : 'a Js.null -> 'a option = "#null_to_opt"
 external return : 'a -> 'a Js.null = "%identity"
diff --git a/jscomp/others/bs_internalAVLtree.ml b/jscomp/others/bs_internalAVLtree.ml
index a9fb7e3c79..22343c2a97 100644
--- a/jscomp/others/bs_internalAVLtree.ml
+++ b/jscomp/others/bs_internalAVLtree.ml
@@ -23,7 +23,7 @@ type ('k, 'v) node  = {
 and ('key, 'a) t = ('key, 'a) node Js.null
 [@@bs.deriving abstract]
 
-type ('k, 'id) cmp = ('k, 'id) Bs_Dict.cmp
+type ('k, 'id) cmp = ('k, 'id) Bs_Id.cmp
     
 module A = Bs_Array 
 module S = Bs_SortArray
@@ -538,7 +538,7 @@ let ofSortedArrayUnsafe arr =
 let rec compareAux e1 e2 ~kcmp ~vcmp =
   match e1,e2 with 
   | h1::t1, h2::t2 ->
-    let c = (Bs_Dict.getCmpInternal kcmp) (key h1) (key h2) [@bs] in 
+    let c = (Bs_Id.getCmpInternal kcmp) (key h1) (key h2) [@bs] in 
     if c = 0 then 
       let cx = vcmp (value h1) (value h2) [@bs] in 
       if cx = 0 then
@@ -552,7 +552,7 @@ let rec compareAux e1 e2 ~kcmp ~vcmp =
 let rec eqAux e1 e2 ~kcmp ~veq =
   match e1,e2 with 
   | h1::t1, h2::t2 ->
-    if (Bs_Dict.getCmpInternal kcmp) (key h1) (key h2) [@bs] = 0 && 
+    if (Bs_Id.getCmpInternal kcmp) (key h1) (key h2) [@bs] = 0 && 
        veq (value h1) (value h2) [@bs] then
       eqAux ~kcmp ~veq (
         stackAllLeft  (right h1) t1 ) (stackAllLeft (right h2) t2)
@@ -582,7 +582,7 @@ let rec get  n x ~cmp =
     None -> None
   | Some n (* Node(l, v, d, r, _) *)  ->
     let v = key n in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     if c = 0 then Some (value n)
     else get ~cmp  (if c < 0 then left n else right n) x 
 
@@ -591,7 +591,7 @@ let rec getUndefined  n x ~cmp =
   | None -> Js.undefined
   | Some n  ->
     let v = key n in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     if c = 0 then Js.Undefined.return (value n )
     else getUndefined ~cmp  (if c < 0 then left n else right n) x 
 
@@ -601,7 +601,7 @@ let rec getExn   n x  ~cmp =
     [%assert "getExn0"]
   | Some n (* Node(l, v, d, r, _)*) ->
     let v = key n in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     if c = 0 then value n 
     else getExn ~cmp  (if c < 0 then left n else right n) x
 
@@ -611,7 +611,7 @@ let rec getWithDefault   n x def ~cmp =
     def
   | Some n (* Node(l, v, d, r, _)*) ->
     let v = key n in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     if c = 0 then value n 
     else getWithDefault ~cmp  (if c < 0 then left n else right n) x def
 
@@ -621,7 +621,7 @@ let rec has  n x ~cmp =
     false
   | Some n (* Node(l, v, d, r, _) *) ->
     let v = key n in 
-    let c = (Bs_Dict.getCmpInternal cmp) x v [@bs] in
+    let c = (Bs_Id.getCmpInternal cmp) x v [@bs] in
     c = 0 || has ~cmp (if c < 0 then left n else right n) x
 
 
@@ -700,7 +700,7 @@ let rec updateMutate (t : _ t) x data ~cmp =
   | None -> singleton x data
   | Some nt -> 
     let k = key nt in 
-    let  c = (Bs_Dict.getCmpInternal cmp) x k [@bs] in  
+    let  c = (Bs_Id.getCmpInternal cmp) x k [@bs] in  
     if c = 0 then begin     
       valueSet nt data;
       return nt
@@ -722,7 +722,7 @@ let ofArray (xs : _ array) ~cmp =
     let next = 
       ref (S.strictlySortedLengthU xs 
              (fun[@bs] (x0,_) (y0,_) -> 
-                (Bs_Dict.getCmpInternal cmp) x0 y0 [@bs] < 0
+                (Bs_Id.getCmpInternal cmp) x0 y0 [@bs] < 0
              ))
     in 
     let result  = ref (
diff --git a/jscomp/others/bs_internalAVLtree.mli b/jscomp/others/bs_internalAVLtree.mli
index b43db0d6d6..5a22a53729 100644
--- a/jscomp/others/bs_internalAVLtree.mli
+++ b/jscomp/others/bs_internalAVLtree.mli
@@ -39,7 +39,7 @@ external toOpt : 'a Js.null -> 'a option = "#null_to_opt"
 external return : 'a -> 'a Js.null = "%identity"
 external empty : 'a Js.null = "#null"
 
-type ('k, 'id) cmp = ('k, 'id) Bs_Dict.cmp
+type ('k, 'id) cmp = ('k, 'id) Bs_Id.cmp
     
 val copy : ('k, 'v) t -> ('k, 'v) t
 val create :
diff --git a/jscomp/test/bs.js b/jscomp/test/bs.js
new file mode 100644
index 0000000000..2588aee4d0
--- /dev/null
+++ b/jscomp/test/bs.js
@@ -0,0 +1,43 @@
+'use strict';
+
+
+var Dict = 0;
+
+var $$Array = 0;
+
+var SortArray = 0;
+
+var MutableQueue = 0;
+
+var MutableStack = 0;
+
+var List = 0;
+
+var Range = 0;
+
+var $$Set = 0;
+
+var $$Map = 0;
+
+var MutableSet = 0;
+
+var MutableMap = 0;
+
+var HashSet = 0;
+
+var HashMap = 0;
+
+exports.Dict = Dict;
+exports.$$Array = $$Array;
+exports.SortArray = SortArray;
+exports.MutableQueue = MutableQueue;
+exports.MutableStack = MutableStack;
+exports.List = List;
+exports.Range = Range;
+exports.$$Set = $$Set;
+exports.$$Map = $$Map;
+exports.MutableSet = MutableSet;
+exports.MutableMap = MutableMap;
+exports.HashSet = HashSet;
+exports.HashMap = HashMap;
+/* No side effect */
diff --git a/jscomp/test/bs_array_test.js b/jscomp/test/bs_array_test.js
index 94115ab060..f70827e468 100644
--- a/jscomp/test/bs_array_test.js
+++ b/jscomp/test/bs_array_test.js
@@ -5,6 +5,7 @@ var Block = require("../../lib/js/block.js");
 var Bs_List = require("../../lib/js/bs_List.js");
 var Js_list = require("../../lib/js/js_list.js");
 var Bs_Array = require("../../lib/js/bs_Array.js");
+var Caml_obj = require("../../lib/js/caml_obj.js");
 var Js_vector = require("../../lib/js/js_vector.js");
 var Caml_array = require("../../lib/js/caml_array.js");
 
@@ -13,20 +14,11 @@ var suites = [/* [] */0];
 var test_id = [0];
 
 function eq(loc, x, y) {
-  test_id[0] = test_id[0] + 1 | 0;
-  suites[0] = /* :: */[
-    /* tuple */[
-      loc + (" id " + test_id[0]),
-      (function () {
-          return /* Eq */Block.__(0, [
-                    x,
-                    y
-                  ]);
-        })
-    ],
-    suites[0]
-  ];
-  return /* () */0;
+  return Mt.eq_suites(test_id, suites, loc, x, y);
+}
+
+function b(loc, x) {
+  return Mt.bool_suites(test_id, suites, loc, x);
 }
 
 function neq(loc, x, y) {
@@ -60,10 +52,10 @@ console.log(/* int array */[
           }), 0));
 
 function id(x) {
-  return eq("File \"bs_array_test.ml\", line 26, characters 5-12", Js_vector.toList(Js_list.toVector(x)), x);
+  return eq("File \"bs_array_test.ml\", line 24, characters 5-12", Js_vector.toList(Js_list.toVector(x)), x);
 }
 
-eq("File \"bs_array_test.ml\", line 30, characters 5-12", Js_list.toVector(/* :: */[
+eq("File \"bs_array_test.ml\", line 28, characters 5-12", Js_list.toVector(/* :: */[
           1,
           /* :: */[
             2,
@@ -78,7 +70,7 @@ eq("File \"bs_array_test.ml\", line 30, characters 5-12", Js_list.toVector(/* ::
       3
     ]);
 
-eq("File \"bs_array_test.ml\", line 31, characters 6-13", Js_vector.map((function (x) {
+eq("File \"bs_array_test.ml\", line 29, characters 6-13", Js_vector.map((function (x) {
             return x + 1 | 0;
           }), /* int array */[
           1,
@@ -90,7 +82,7 @@ eq("File \"bs_array_test.ml\", line 31, characters 6-13", Js_vector.map((functio
       4
     ]);
 
-eq("File \"bs_array_test.ml\", line 34, characters 5-12", Caml_array.caml_make_vect(5, 3), /* array */[
+eq("File \"bs_array_test.ml\", line 32, characters 5-12", Caml_array.caml_make_vect(5, 3), /* array */[
       3,
       3,
       3,
@@ -102,7 +94,7 @@ var a = Js_vector.init(5, (function (i) {
         return i + 1 | 0;
       }));
 
-eq("File \"bs_array_test.ml\", line 36, characters 5-12", (Js_vector.filterInPlace((function (j) {
+eq("File \"bs_array_test.ml\", line 34, characters 5-12", (Js_vector.filterInPlace((function (j) {
               return +(j % 2 === 0);
             }), a), a), /* int array */[
       2,
@@ -113,7 +105,7 @@ var a$1 = Js_vector.init(5, (function (i) {
         return i + 1 | 0;
       }));
 
-eq("File \"bs_array_test.ml\", line 43, characters 5-12", (Js_vector.filterInPlace((function (j) {
+eq("File \"bs_array_test.ml\", line 41, characters 5-12", (Js_vector.filterInPlace((function (j) {
               return +(j % 2 !== 0);
             }), a$1), a$1), /* int array */[
       1,
@@ -121,7 +113,7 @@ eq("File \"bs_array_test.ml\", line 43, characters 5-12", (Js_vector.filterInPla
       5
     ]);
 
-eq("File \"bs_array_test.ml\", line 50, characters 5-12", Js_list.toVector(/* :: */[
+eq("File \"bs_array_test.ml\", line 48, characters 5-12", Js_list.toVector(/* :: */[
           1,
           /* :: */[
             2,
@@ -136,7 +128,7 @@ eq("File \"bs_array_test.ml\", line 50, characters 5-12", Js_list.toVector(/* ::
       3
     ]);
 
-eq("File \"bs_array_test.ml\", line 52, characters 5-12", Js_list.toVector(/* :: */[
+eq("File \"bs_array_test.ml\", line 50, characters 5-12", Js_list.toVector(/* :: */[
           1,
           /* [] */0
         ]), /* int array */[1]);
@@ -179,22 +171,58 @@ var v = Bs_Array.makeBy(3000, (function (i) {
 
 var u = Bs_Array.shuffle(v);
 
-neq("File \"bs_array_test.ml\", line 63, characters 6-13", u, v);
+neq("File \"bs_array_test.ml\", line 61, characters 6-13", u, v);
+
+eq("File \"bs_array_test.ml\", line 63, characters 5-12", Bs_Array.reduce(u, 0, add), Bs_Array.reduce(v, 0, add));
+
+b("File \"bs_array_test.ml\", line 68, characters 4-11", Caml_obj.caml_equal(Bs_Array.range(0, 3), /* int array */[
+          0,
+          1,
+          2,
+          3
+        ]));
+
+b("File \"bs_array_test.ml\", line 69, characters 4-11", Caml_obj.caml_equal(Bs_Array.range(3, 0), /* int array */[]));
+
+b("File \"bs_array_test.ml\", line 70, characters 4-11", Caml_obj.caml_equal(Bs_Array.range(3, 3), /* int array */[3]));
+
+b("File \"bs_array_test.ml\", line 72, characters 4-11", Caml_obj.caml_equal(Bs_Array.rangeBy(0, 10, 3), /* int array */[
+          0,
+          3,
+          6,
+          9
+        ]));
+
+b("File \"bs_array_test.ml\", line 73, characters 4-11", Caml_obj.caml_equal(Bs_Array.rangeBy(0, 12, 3), /* array */[
+          0,
+          3,
+          6,
+          9,
+          12
+        ]));
+
+b("File \"bs_array_test.ml\", line 74, characters 4-11", Caml_obj.caml_equal(Bs_Array.rangeBy(33, 0, 1), /* int array */[]));
+
+b("File \"bs_array_test.ml\", line 75, characters 4-11", Caml_obj.caml_equal(Bs_Array.rangeBy(33, 0, -1), /* int array */[]));
+
+b("File \"bs_array_test.ml\", line 76, characters 4-11", Caml_obj.caml_equal(Bs_Array.rangeBy(3, 12, -1), /* int array */[]));
+
+b("File \"bs_array_test.ml\", line 77, characters 4-11", Caml_obj.caml_equal(Bs_Array.rangeBy(3, 3, 0), /* int array */[]));
 
-eq("File \"bs_array_test.ml\", line 65, characters 5-12", Bs_Array.reduce(u, 0, add), Bs_Array.reduce(v, 0, add));
+b("File \"bs_array_test.ml\", line 78, characters 4-11", Caml_obj.caml_equal(Bs_Array.rangeBy(3, 3, 1), /* int array */[3]));
 
-eq("File \"bs_array_test.ml\", line 68, characters 5-12", Bs_Array.reduceReverse(/* int array */[], 100, (function (prim, prim$1) {
+eq("File \"bs_array_test.ml\", line 83, characters 5-12", Bs_Array.reduceReverse(/* int array */[], 100, (function (prim, prim$1) {
             return prim - prim$1 | 0;
           })), 100);
 
-eq("File \"bs_array_test.ml\", line 69, characters 5-12", Bs_Array.reduceReverse(/* int array */[
+eq("File \"bs_array_test.ml\", line 84, characters 5-12", Bs_Array.reduceReverse(/* int array */[
           1,
           2
         ], 100, (function (prim, prim$1) {
             return prim - prim$1 | 0;
           })), 97);
 
-eq("File \"bs_array_test.ml\", line 70, characters 5-12", Bs_Array.reduceReverse(/* int array */[
+eq("File \"bs_array_test.ml\", line 85, characters 5-12", Bs_Array.reduceReverse(/* int array */[
           1,
           2,
           3,
@@ -209,7 +237,7 @@ function addone(x) {
 
 function makeMatrixExn(sx, sy, init) {
   if (!(sx >= 0 && sy >= 0)) {
-    throw new Error("File \"bs_array_test.ml\", line 75, characters 4-10");
+    throw new Error("File \"bs_array_test.ml\", line 90, characters 4-10");
   }
   var res = new Array(sx);
   for(var x = 0 ,x_finish = sx - 1 | 0; x <= x_finish; ++x){
@@ -222,11 +250,11 @@ function makeMatrixExn(sx, sy, init) {
   return res;
 }
 
-eq("File \"bs_array_test.ml\", line 87, characters 5-12", Bs_Array.makeBy(0, (function () {
+eq("File \"bs_array_test.ml\", line 102, characters 5-12", Bs_Array.makeBy(0, (function () {
             return 1;
           })), /* int array */[]);
 
-eq("File \"bs_array_test.ml\", line 88, characters 5-12", Bs_Array.makeBy(3, (function (i) {
+eq("File \"bs_array_test.ml\", line 103, characters 5-12", Bs_Array.makeBy(3, (function (i) {
             return i;
           })), /* int array */[
       0,
@@ -234,7 +262,7 @@ eq("File \"bs_array_test.ml\", line 88, characters 5-12", Bs_Array.makeBy(3, (fu
       2
     ]);
 
-eq("File \"bs_array_test.ml\", line 89, characters 5-12", makeMatrixExn(3, 4, 1), /* array */[
+eq("File \"bs_array_test.ml\", line 104, characters 5-12", makeMatrixExn(3, 4, 1), /* array */[
       /* int array */[
         1,
         1,
@@ -255,25 +283,25 @@ eq("File \"bs_array_test.ml\", line 89, characters 5-12", makeMatrixExn(3, 4, 1)
       ]
     ]);
 
-eq("File \"bs_array_test.ml\", line 92, characters 5-12", makeMatrixExn(3, 0, 0), /* array */[
+eq("File \"bs_array_test.ml\", line 107, characters 5-12", makeMatrixExn(3, 0, 0), /* array */[
       /* int array */[],
       /* int array */[],
       /* int array */[]
     ]);
 
-eq("File \"bs_array_test.ml\", line 93, characters 5-12", makeMatrixExn(0, 3, 1), /* array */[]);
+eq("File \"bs_array_test.ml\", line 108, characters 5-12", makeMatrixExn(0, 3, 1), /* array */[]);
 
-eq("File \"bs_array_test.ml\", line 94, characters 5-12", makeMatrixExn(1, 1, 1), /* array */[/* int array */[1]]);
+eq("File \"bs_array_test.ml\", line 109, characters 5-12", makeMatrixExn(1, 1, 1), /* array */[/* int array */[1]]);
 
-eq("File \"bs_array_test.ml\", line 95, characters 5-12", Bs_Array.copy(/* array */[]), /* array */[]);
+eq("File \"bs_array_test.ml\", line 110, characters 5-12", Bs_Array.copy(/* array */[]), /* array */[]);
 
-eq("File \"bs_array_test.ml\", line 96, characters 5-12", Bs_Array.map(/* int array */[], (function (prim) {
+eq("File \"bs_array_test.ml\", line 111, characters 5-12", Bs_Array.map(/* int array */[], (function (prim) {
             return prim + 1 | 0;
           })), /* int array */[]);
 
-eq("File \"bs_array_test.ml\", line 97, characters 5-12", Bs_Array.mapWithIndex(/* int array */[], add), /* int array */[]);
+eq("File \"bs_array_test.ml\", line 112, characters 5-12", Bs_Array.mapWithIndex(/* int array */[], add), /* int array */[]);
 
-eq("File \"bs_array_test.ml\", line 98, characters 5-12", Bs_Array.mapWithIndex(/* int array */[
+eq("File \"bs_array_test.ml\", line 113, characters 5-12", Bs_Array.mapWithIndex(/* int array */[
           1,
           2,
           3
@@ -283,14 +311,14 @@ eq("File \"bs_array_test.ml\", line 98, characters 5-12", Bs_Array.mapWithIndex(
       5
     ]);
 
-eq("File \"bs_array_test.ml\", line 99, characters 5-12", Bs_List.ofArray(/* array */[]), /* [] */0);
+eq("File \"bs_array_test.ml\", line 114, characters 5-12", Bs_List.ofArray(/* array */[]), /* [] */0);
 
-eq("File \"bs_array_test.ml\", line 100, characters 5-12", Bs_List.ofArray(/* int array */[1]), /* :: */[
+eq("File \"bs_array_test.ml\", line 115, characters 5-12", Bs_List.ofArray(/* int array */[1]), /* :: */[
       1,
       /* [] */0
     ]);
 
-eq("File \"bs_array_test.ml\", line 101, characters 5-12", Bs_List.ofArray(/* int array */[
+eq("File \"bs_array_test.ml\", line 116, characters 5-12", Bs_List.ofArray(/* int array */[
           1,
           2,
           3
@@ -305,7 +333,7 @@ eq("File \"bs_array_test.ml\", line 101, characters 5-12", Bs_List.ofArray(/* in
       ]
     ]);
 
-eq("File \"bs_array_test.ml\", line 102, characters 5-12", Bs_Array.map(/* int array */[
+eq("File \"bs_array_test.ml\", line 117, characters 5-12", Bs_Array.map(/* int array */[
           1,
           2,
           3
@@ -317,14 +345,14 @@ eq("File \"bs_array_test.ml\", line 102, characters 5-12", Bs_Array.map(/* int a
       4
     ]);
 
-eq("File \"bs_array_test.ml\", line 103, characters 5-12", Bs_List.toArray(/* [] */0), /* array */[]);
+eq("File \"bs_array_test.ml\", line 118, characters 5-12", Bs_List.toArray(/* [] */0), /* array */[]);
 
-eq("File \"bs_array_test.ml\", line 104, characters 5-12", Bs_List.toArray(/* :: */[
+eq("File \"bs_array_test.ml\", line 119, characters 5-12", Bs_List.toArray(/* :: */[
           1,
           /* [] */0
         ]), /* int array */[1]);
 
-eq("File \"bs_array_test.ml\", line 105, characters 5-12", Bs_List.toArray(/* :: */[
+eq("File \"bs_array_test.ml\", line 120, characters 5-12", Bs_List.toArray(/* :: */[
           1,
           /* :: */[
             2,
@@ -335,7 +363,7 @@ eq("File \"bs_array_test.ml\", line 105, characters 5-12", Bs_List.toArray(/* ::
       2
     ]);
 
-eq("File \"bs_array_test.ml\", line 106, characters 5-12", Bs_List.toArray(/* :: */[
+eq("File \"bs_array_test.ml\", line 121, characters 5-12", Bs_List.toArray(/* :: */[
           1,
           /* :: */[
             2,
@@ -370,7 +398,7 @@ var v2 = Bs_Array.keepMap(v$1, (function (x) {
         }
       }));
 
-eq("File \"bs_array_test.ml\", line 113, characters 5-12", v0, /* array */[
+eq("File \"bs_array_test.ml\", line 128, characters 5-12", v0, /* array */[
       0,
       2,
       4,
@@ -378,14 +406,14 @@ eq("File \"bs_array_test.ml\", line 113, characters 5-12", v0, /* array */[
       8
     ]);
 
-eq("File \"bs_array_test.ml\", line 114, characters 5-12", v1, /* int array */[
+eq("File \"bs_array_test.ml\", line 129, characters 5-12", v1, /* int array */[
       0,
       3,
       6,
       9
     ]);
 
-eq("File \"bs_array_test.ml\", line 115, characters 5-12", v2, /* array */[
+eq("File \"bs_array_test.ml\", line 130, characters 5-12", v2, /* array */[
       1,
       3,
       5,
@@ -401,12 +429,12 @@ var a$2 = /* array */[
   5
 ];
 
-eq("File \"bs_array_test.ml\", line 119, characters 5-12", Bs_Array.slice(a$2, 0, 2), /* int array */[
+eq("File \"bs_array_test.ml\", line 134, characters 5-12", Bs_Array.slice(a$2, 0, 2), /* int array */[
       1,
       2
     ]);
 
-eq("File \"bs_array_test.ml\", line 120, characters 5-12", Bs_Array.slice(a$2, 0, 5), /* array */[
+eq("File \"bs_array_test.ml\", line 135, characters 5-12", Bs_Array.slice(a$2, 0, 5), /* array */[
       1,
       2,
       3,
@@ -414,7 +442,7 @@ eq("File \"bs_array_test.ml\", line 120, characters 5-12", Bs_Array.slice(a$2, 0
       5
     ]);
 
-eq("File \"bs_array_test.ml\", line 121, characters 5-12", Bs_Array.slice(a$2, 0, 15), /* array */[
+eq("File \"bs_array_test.ml\", line 136, characters 5-12", Bs_Array.slice(a$2, 0, 15), /* array */[
       1,
       2,
       3,
@@ -422,40 +450,40 @@ eq("File \"bs_array_test.ml\", line 121, characters 5-12", Bs_Array.slice(a$2, 0
       5
     ]);
 
-eq("File \"bs_array_test.ml\", line 122, characters 5-12", Bs_Array.slice(a$2, 5, 1), /* int array */[]);
+eq("File \"bs_array_test.ml\", line 137, characters 5-12", Bs_Array.slice(a$2, 5, 1), /* int array */[]);
 
-eq("File \"bs_array_test.ml\", line 123, characters 5-12", Bs_Array.slice(a$2, 4, 1), /* int array */[5]);
+eq("File \"bs_array_test.ml\", line 138, characters 5-12", Bs_Array.slice(a$2, 4, 1), /* int array */[5]);
 
-eq("File \"bs_array_test.ml\", line 124, characters 5-12", Bs_Array.slice(a$2, -1, 1), /* int array */[5]);
+eq("File \"bs_array_test.ml\", line 139, characters 5-12", Bs_Array.slice(a$2, -1, 1), /* int array */[5]);
 
-eq("File \"bs_array_test.ml\", line 125, characters 5-12", Bs_Array.slice(a$2, -1, 2), /* int array */[5]);
+eq("File \"bs_array_test.ml\", line 140, characters 5-12", Bs_Array.slice(a$2, -1, 2), /* int array */[5]);
 
-eq("File \"bs_array_test.ml\", line 126, characters 5-12", Bs_Array.slice(a$2, -2, 1), /* int array */[4]);
+eq("File \"bs_array_test.ml\", line 141, characters 5-12", Bs_Array.slice(a$2, -2, 1), /* int array */[4]);
 
-eq("File \"bs_array_test.ml\", line 127, characters 5-12", Bs_Array.slice(a$2, -2, 2), /* int array */[
+eq("File \"bs_array_test.ml\", line 142, characters 5-12", Bs_Array.slice(a$2, -2, 2), /* int array */[
       4,
       5
     ]);
 
-eq("File \"bs_array_test.ml\", line 128, characters 5-12", Bs_Array.slice(a$2, -2, 3), /* int array */[
+eq("File \"bs_array_test.ml\", line 143, characters 5-12", Bs_Array.slice(a$2, -2, 3), /* int array */[
       4,
       5
     ]);
 
-eq("File \"bs_array_test.ml\", line 129, characters 5-12", Bs_Array.slice(a$2, -10, 3), /* int array */[
+eq("File \"bs_array_test.ml\", line 144, characters 5-12", Bs_Array.slice(a$2, -10, 3), /* int array */[
       1,
       2,
       3
     ]);
 
-eq("File \"bs_array_test.ml\", line 130, characters 5-12", Bs_Array.slice(a$2, -10, 4), /* int array */[
+eq("File \"bs_array_test.ml\", line 145, characters 5-12", Bs_Array.slice(a$2, -10, 4), /* int array */[
       1,
       2,
       3,
       4
     ]);
 
-eq("File \"bs_array_test.ml\", line 131, characters 5-12", Bs_Array.slice(a$2, -10, 5), /* array */[
+eq("File \"bs_array_test.ml\", line 146, characters 5-12", Bs_Array.slice(a$2, -10, 5), /* array */[
       1,
       2,
       3,
@@ -463,7 +491,7 @@ eq("File \"bs_array_test.ml\", line 131, characters 5-12", Bs_Array.slice(a$2, -
       5
     ]);
 
-eq("File \"bs_array_test.ml\", line 132, characters 5-12", Bs_Array.slice(a$2, -10, 6), /* array */[
+eq("File \"bs_array_test.ml\", line 147, characters 5-12", Bs_Array.slice(a$2, -10, 6), /* array */[
       1,
       2,
       3,
@@ -471,9 +499,9 @@ eq("File \"bs_array_test.ml\", line 132, characters 5-12", Bs_Array.slice(a$2, -
       5
     ]);
 
-eq("File \"bs_array_test.ml\", line 133, characters 5-12", Bs_Array.slice(a$2, 0, 0), /* int array */[]);
+eq("File \"bs_array_test.ml\", line 148, characters 5-12", Bs_Array.slice(a$2, 0, 0), /* int array */[]);
 
-eq("File \"bs_array_test.ml\", line 134, characters 5-12", Bs_Array.slice(a$2, 0, -1), /* int array */[]);
+eq("File \"bs_array_test.ml\", line 149, characters 5-12", Bs_Array.slice(a$2, 0, -1), /* int array */[]);
 
 var a$3 = Bs_Array.makeBy(10, (function (x) {
         return x;
@@ -481,7 +509,7 @@ var a$3 = Bs_Array.makeBy(10, (function (x) {
 
 Bs_Array.fill(a$3, 0, 3, 0);
 
-eq("File \"bs_array_test.ml\", line 139, characters 6-13", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 154, characters 6-13", Bs_Array.copy(a$3), /* array */[
       0,
       0,
       0,
@@ -496,7 +524,7 @@ eq("File \"bs_array_test.ml\", line 139, characters 6-13", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, 2, 8, 1);
 
-eq("File \"bs_array_test.ml\", line 141, characters 5-12", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 156, characters 5-12", Bs_Array.copy(a$3), /* array */[
       0,
       0,
       1,
@@ -511,7 +539,7 @@ eq("File \"bs_array_test.ml\", line 141, characters 5-12", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, 8, 1, 9);
 
-eq("File \"bs_array_test.ml\", line 143, characters 5-12", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 158, characters 5-12", Bs_Array.copy(a$3), /* array */[
       0,
       0,
       1,
@@ -526,7 +554,7 @@ eq("File \"bs_array_test.ml\", line 143, characters 5-12", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, 8, 2, 9);
 
-eq("File \"bs_array_test.ml\", line 145, characters 5-12", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 160, characters 5-12", Bs_Array.copy(a$3), /* array */[
       0,
       0,
       1,
@@ -541,7 +569,7 @@ eq("File \"bs_array_test.ml\", line 145, characters 5-12", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, 8, 3, 12);
 
-eq("File \"bs_array_test.ml\", line 147, characters 5-12", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 162, characters 5-12", Bs_Array.copy(a$3), /* array */[
       0,
       0,
       1,
@@ -556,7 +584,7 @@ eq("File \"bs_array_test.ml\", line 147, characters 5-12", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, -2, 3, 11);
 
-eq("File \"bs_array_test.ml\", line 149, characters 5-12", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 164, characters 5-12", Bs_Array.copy(a$3), /* array */[
       0,
       0,
       1,
@@ -571,7 +599,7 @@ eq("File \"bs_array_test.ml\", line 149, characters 5-12", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, -3, 3, 10);
 
-eq("File \"bs_array_test.ml\", line 151, characters 5-12", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 166, characters 5-12", Bs_Array.copy(a$3), /* array */[
       0,
       0,
       1,
@@ -586,7 +614,7 @@ eq("File \"bs_array_test.ml\", line 151, characters 5-12", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, -3, 1, 7);
 
-eq("File \"bs_array_test.ml\", line 153, characters 5-12", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 168, characters 5-12", Bs_Array.copy(a$3), /* array */[
       0,
       0,
       1,
@@ -601,7 +629,7 @@ eq("File \"bs_array_test.ml\", line 153, characters 5-12", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, -13, 1, 7);
 
-eq("File \"bs_array_test.ml\", line 155, characters 5-12", Bs_Array.copy(a$3), /* array */[
+eq("File \"bs_array_test.ml\", line 170, characters 5-12", Bs_Array.copy(a$3), /* array */[
       7,
       0,
       1,
@@ -616,11 +644,11 @@ eq("File \"bs_array_test.ml\", line 155, characters 5-12", Bs_Array.copy(a$3), /
 
 Bs_Array.fill(a$3, -13, 12, 7);
 
-eq("File \"bs_array_test.ml\", line 157, characters 5-12", Bs_Array.copy(a$3), Bs_Array.make(10, 7));
+eq("File \"bs_array_test.ml\", line 172, characters 5-12", Bs_Array.copy(a$3), Bs_Array.make(10, 7));
 
 Bs_Array.fill(a$3, 0, -1, 2);
 
-eq("File \"bs_array_test.ml\", line 159, characters 5-12", Bs_Array.copy(a$3), Bs_Array.make(10, 7));
+eq("File \"bs_array_test.ml\", line 174, characters 5-12", Bs_Array.copy(a$3), Bs_Array.make(10, 7));
 
 var a0 = Bs_Array.makeBy(10, (function (x) {
         return x;
@@ -630,7 +658,7 @@ var b0 = Bs_Array.make(10, 3);
 
 Bs_Array.blit(a0, 1, b0, 2, 5);
 
-eq("File \"bs_array_test.ml\", line 165, characters 5-12", Bs_Array.copy(b0), /* array */[
+eq("File \"bs_array_test.ml\", line 180, characters 5-12", Bs_Array.copy(b0), /* array */[
       3,
       3,
       1,
@@ -645,7 +673,7 @@ eq("File \"bs_array_test.ml\", line 165, characters 5-12", Bs_Array.copy(b0), /*
 
 Bs_Array.blit(a0, -1, b0, 2, 5);
 
-eq("File \"bs_array_test.ml\", line 168, characters 5-12", Bs_Array.copy(b0), /* array */[
+eq("File \"bs_array_test.ml\", line 183, characters 5-12", Bs_Array.copy(b0), /* array */[
       3,
       3,
       9,
@@ -660,7 +688,7 @@ eq("File \"bs_array_test.ml\", line 168, characters 5-12", Bs_Array.copy(b0), /*
 
 Bs_Array.blit(a0, -1, b0, -2, 5);
 
-eq("File \"bs_array_test.ml\", line 171, characters 5-12", Bs_Array.copy(b0), /* array */[
+eq("File \"bs_array_test.ml\", line 186, characters 5-12", Bs_Array.copy(b0), /* array */[
       3,
       3,
       9,
@@ -675,7 +703,7 @@ eq("File \"bs_array_test.ml\", line 171, characters 5-12", Bs_Array.copy(b0), /*
 
 Bs_Array.blit(a0, -2, b0, -2, 2);
 
-eq("File \"bs_array_test.ml\", line 174, characters 5-12", Bs_Array.copy(b0), /* array */[
+eq("File \"bs_array_test.ml\", line 189, characters 5-12", Bs_Array.copy(b0), /* array */[
       3,
       3,
       9,
@@ -690,11 +718,11 @@ eq("File \"bs_array_test.ml\", line 174, characters 5-12", Bs_Array.copy(b0), /*
 
 Bs_Array.blit(a0, -11, b0, -11, 100);
 
-eq("File \"bs_array_test.ml\", line 177, characters 5-12", Bs_Array.copy(b0), a0);
+eq("File \"bs_array_test.ml\", line 192, characters 5-12", Bs_Array.copy(b0), a0);
 
 Bs_Array.blit(a0, -11, b0, -11, 2);
 
-eq("File \"bs_array_test.ml\", line 179, characters 5-12", Bs_Array.copy(b0), a0);
+eq("File \"bs_array_test.ml\", line 194, characters 5-12", Bs_Array.copy(b0), a0);
 
 var aa = Bs_Array.makeBy(10, (function (x) {
         return x;
@@ -702,7 +730,7 @@ var aa = Bs_Array.makeBy(10, (function (x) {
 
 Bs_Array.blit(aa, -1, aa, 1, 2);
 
-eq("File \"bs_array_test.ml\", line 182, characters 5-12", Bs_Array.copy(aa), /* array */[
+eq("File \"bs_array_test.ml\", line 197, characters 5-12", Bs_Array.copy(aa), /* array */[
       0,
       9,
       2,
@@ -717,7 +745,7 @@ eq("File \"bs_array_test.ml\", line 182, characters 5-12", Bs_Array.copy(aa), /*
 
 Bs_Array.blit(aa, -2, aa, 1, 2);
 
-eq("File \"bs_array_test.ml\", line 184, characters 5-12", Bs_Array.copy(aa), /* array */[
+eq("File \"bs_array_test.ml\", line 199, characters 5-12", Bs_Array.copy(aa), /* array */[
       0,
       8,
       9,
@@ -732,7 +760,7 @@ eq("File \"bs_array_test.ml\", line 184, characters 5-12", Bs_Array.copy(aa), /*
 
 Bs_Array.blit(aa, -5, aa, 4, 3);
 
-eq("File \"bs_array_test.ml\", line 186, characters 5-12", Bs_Array.copy(aa), /* array */[
+eq("File \"bs_array_test.ml\", line 201, characters 5-12", Bs_Array.copy(aa), /* array */[
       0,
       8,
       9,
@@ -747,7 +775,7 @@ eq("File \"bs_array_test.ml\", line 186, characters 5-12", Bs_Array.copy(aa), /*
 
 Bs_Array.blit(aa, 4, aa, 5, 3);
 
-eq("File \"bs_array_test.ml\", line 188, characters 5-12", Bs_Array.copy(aa), /* array */[
+eq("File \"bs_array_test.ml\", line 203, characters 5-12", Bs_Array.copy(aa), /* array */[
       0,
       8,
       9,
@@ -762,25 +790,25 @@ eq("File \"bs_array_test.ml\", line 188, characters 5-12", Bs_Array.copy(aa), /*
 
 function id$1(_, x) {
   var u = Bs_Array.copy(x);
-  return eq("File \"bs_array_test.ml\", line 191, characters 5-12", Bs_Array.reverse(x), (Bs_Array.reverseInPlace(u), u));
+  return eq("File \"bs_array_test.ml\", line 206, characters 5-12", Bs_Array.reverse(x), (Bs_Array.reverseInPlace(u), u));
 }
 
-id$1("File \"bs_array_test.ml\", line 196, characters 5-12", /* array */[]);
+id$1("File \"bs_array_test.ml\", line 211, characters 5-12", /* array */[]);
 
-id$1("File \"bs_array_test.ml\", line 197, characters 5-12", /* int array */[1]);
+id$1("File \"bs_array_test.ml\", line 212, characters 5-12", /* int array */[1]);
 
-id$1("File \"bs_array_test.ml\", line 198, characters 5-12", /* int array */[
+id$1("File \"bs_array_test.ml\", line 213, characters 5-12", /* int array */[
       1,
       2
     ]);
 
-id$1("File \"bs_array_test.ml\", line 199, characters 5-12", /* int array */[
+id$1("File \"bs_array_test.ml\", line 214, characters 5-12", /* int array */[
       1,
       2,
       3
     ]);
 
-id$1("File \"bs_array_test.ml\", line 200, characters 5-12", /* int array */[
+id$1("File \"bs_array_test.ml\", line 215, characters 5-12", /* int array */[
       1,
       2,
       3,
@@ -803,14 +831,14 @@ function some2(xs, ys) {
     });
 }
 
-eq("File \"bs_array_test.ml\", line 210, characters 5-12", every2(/* [] */0, /* :: */[
+eq("File \"bs_array_test.ml\", line 225, characters 5-12", every2(/* [] */0, /* :: */[
             1,
             /* [] */0
           ])((function (x, y) {
             return +(x > y);
           })), /* true */1);
 
-eq("File \"bs_array_test.ml\", line 211, characters 5-12", every2(/* :: */[
+eq("File \"bs_array_test.ml\", line 226, characters 5-12", every2(/* :: */[
             2,
             /* :: */[
               3,
@@ -823,7 +851,7 @@ eq("File \"bs_array_test.ml\", line 211, characters 5-12", every2(/* :: */[
             return +(x > y);
           })), /* true */1);
 
-eq("File \"bs_array_test.ml\", line 212, characters 5-12", every2(/* :: */[
+eq("File \"bs_array_test.ml\", line 227, characters 5-12", every2(/* :: */[
             2,
             /* [] */0
           ], /* :: */[
@@ -833,7 +861,7 @@ eq("File \"bs_array_test.ml\", line 212, characters 5-12", every2(/* :: */[
             return +(x > y);
           })), /* true */1);
 
-eq("File \"bs_array_test.ml\", line 213, characters 5-12", every2(/* :: */[
+eq("File \"bs_array_test.ml\", line 228, characters 5-12", every2(/* :: */[
             2,
             /* :: */[
               3,
@@ -849,7 +877,7 @@ eq("File \"bs_array_test.ml\", line 213, characters 5-12", every2(/* :: */[
             return +(x > y);
           })), /* false */0);
 
-eq("File \"bs_array_test.ml\", line 214, characters 5-12", every2(/* :: */[
+eq("File \"bs_array_test.ml\", line 229, characters 5-12", every2(/* :: */[
             2,
             /* :: */[
               3,
@@ -865,14 +893,14 @@ eq("File \"bs_array_test.ml\", line 214, characters 5-12", every2(/* :: */[
             return +(x > y);
           })), /* true */1);
 
-eq("File \"bs_array_test.ml\", line 215, characters 5-12", some2(/* [] */0, /* :: */[
+eq("File \"bs_array_test.ml\", line 230, characters 5-12", some2(/* [] */0, /* :: */[
             1,
             /* [] */0
           ])((function (x, y) {
             return +(x > y);
           })), /* false */0);
 
-eq("File \"bs_array_test.ml\", line 216, characters 5-12", some2(/* :: */[
+eq("File \"bs_array_test.ml\", line 231, characters 5-12", some2(/* :: */[
             2,
             /* :: */[
               3,
@@ -885,7 +913,7 @@ eq("File \"bs_array_test.ml\", line 216, characters 5-12", some2(/* :: */[
             return +(x > y);
           })), /* true */1);
 
-eq("File \"bs_array_test.ml\", line 217, characters 5-12", some2(/* :: */[
+eq("File \"bs_array_test.ml\", line 232, characters 5-12", some2(/* :: */[
             2,
             /* :: */[
               3,
@@ -901,7 +929,7 @@ eq("File \"bs_array_test.ml\", line 217, characters 5-12", some2(/* :: */[
             return +(x > y);
           })), /* true */1);
 
-eq("File \"bs_array_test.ml\", line 218, characters 5-12", some2(/* :: */[
+eq("File \"bs_array_test.ml\", line 233, characters 5-12", some2(/* :: */[
             0,
             /* :: */[
               3,
@@ -917,7 +945,7 @@ eq("File \"bs_array_test.ml\", line 218, characters 5-12", some2(/* :: */[
             return +(x > y);
           })), /* false */0);
 
-eq("File \"bs_array_test.ml\", line 219, characters 5-12", some2(/* :: */[
+eq("File \"bs_array_test.ml\", line 234, characters 5-12", some2(/* :: */[
             0,
             /* :: */[
               3,
@@ -933,7 +961,7 @@ eq("File \"bs_array_test.ml\", line 219, characters 5-12", some2(/* :: */[
             return +(x > y);
           })), /* true */1);
 
-eq("File \"bs_array_test.ml\", line 224, characters 5-12", Bs_Array.concat(/* int array */[], /* int array */[
+eq("File \"bs_array_test.ml\", line 239, characters 5-12", Bs_Array.concat(/* int array */[], /* int array */[
           1,
           2,
           3
@@ -943,9 +971,9 @@ eq("File \"bs_array_test.ml\", line 224, characters 5-12", Bs_Array.concat(/* in
       3
     ]);
 
-eq("File \"bs_array_test.ml\", line 225, characters 5-12", Bs_Array.concat(/* array */[], /* array */[]), /* array */[]);
+eq("File \"bs_array_test.ml\", line 240, characters 5-12", Bs_Array.concat(/* array */[], /* array */[]), /* array */[]);
 
-eq("File \"bs_array_test.ml\", line 226, characters 5-12", Bs_Array.concat(/* int array */[
+eq("File \"bs_array_test.ml\", line 241, characters 5-12", Bs_Array.concat(/* int array */[
           3,
           2
         ], /* int array */[
@@ -960,7 +988,7 @@ eq("File \"bs_array_test.ml\", line 226, characters 5-12", Bs_Array.concat(/* in
       3
     ]);
 
-eq("File \"bs_array_test.ml\", line 227, characters 5-12", Bs_Array.concatMany(/* array */[
+eq("File \"bs_array_test.ml\", line 242, characters 5-12", Bs_Array.concatMany(/* array */[
           /* int array */[
             3,
             2
@@ -978,7 +1006,7 @@ eq("File \"bs_array_test.ml\", line 227, characters 5-12", Bs_Array.concatMany(/
       3
     ]);
 
-eq("File \"bs_array_test.ml\", line 228, characters 5-12", Bs_Array.concatMany(/* array */[
+eq("File \"bs_array_test.ml\", line 243, characters 5-12", Bs_Array.concatMany(/* array */[
           /* int array */[
             3,
             2
@@ -999,7 +1027,7 @@ eq("File \"bs_array_test.ml\", line 228, characters 5-12", Bs_Array.concatMany(/
       0
     ]);
 
-eq("File \"bs_array_test.ml\", line 229, characters 5-12", Bs_Array.concatMany(/* array */[
+eq("File \"bs_array_test.ml\", line 244, characters 5-12", Bs_Array.concatMany(/* array */[
           /* int array */[],
           /* int array */[
             3,
@@ -1021,12 +1049,12 @@ eq("File \"bs_array_test.ml\", line 229, characters 5-12", Bs_Array.concatMany(/
       0
     ]);
 
-eq("File \"bs_array_test.ml\", line 230, characters 5-12", Bs_Array.concatMany(/* array */[
+eq("File \"bs_array_test.ml\", line 245, characters 5-12", Bs_Array.concatMany(/* array */[
           /* array */[],
           /* array */[]
         ]), /* array */[]);
 
-Mt.from_pair_suites("File \"bs_array_test.ml\", line 232, characters 23-30", suites[0]);
+Mt.from_pair_suites("File \"bs_array_test.ml\", line 247, characters 23-30", suites[0]);
 
 var A = 0;
 
@@ -1035,6 +1063,7 @@ var L = 0;
 exports.suites = suites;
 exports.test_id = test_id;
 exports.eq = eq;
+exports.b = b;
 exports.neq = neq;
 exports.A = A;
 exports.L = L;
diff --git a/jscomp/test/bs_array_test.ml b/jscomp/test/bs_array_test.ml
index 2cec95a24b..be14b7059c 100644
--- a/jscomp/test/bs_array_test.ml
+++ b/jscomp/test/bs_array_test.ml
@@ -1,10 +1,8 @@
 
 let suites :  Mt.pair_suites ref  = ref []
 let test_id = ref 0
-let eq loc x y = 
-  incr test_id ; 
-  suites := 
-    (loc ^" id " ^ (string_of_int !test_id), (fun _ -> Mt.Eq(x,y))) :: !suites
+let eq loc x y = Mt.eq_suites loc x y ~test_id ~suites
+let b loc x  = Mt.bool_suites loc x ~test_id ~suites
 let neq loc x y = 
   incr test_id ; 
   suites := 
@@ -64,6 +62,23 @@ let () =
   let sum x = A.reduce x 0 add in 
   eq __LOC__ ( sum u) (sum v)
 
+
+let () =
+  let open A in 
+  b __LOC__ (range 0 3 =  [|0;1;2;3|]);
+  b __LOC__ (range 3 0 =  [||] );
+  b __LOC__ (range 3 3 = [|3|]);
+
+  b __LOC__ (rangeBy 0 10 ~step:3 = [|0;3;6;9|]);
+  b __LOC__ (rangeBy 0 12 ~step:3 = [|0;3;6;9;12|]);
+  b __LOC__ (rangeBy 33 0 ~step:1 =  [||]);
+  b __LOC__ (rangeBy 33 0 ~step:(-1) = [||]);
+  b __LOC__ (rangeBy 3 12 ~step:(-1) = [||]);
+  b __LOC__ (rangeBy 3 3 ~step:0 = [||] );     
+  b __LOC__ (rangeBy 3 3 ~step:(1) = [|3|])
+
+
+
 let () = 
   eq __LOC__ (A.reduceReverse [||] 100 (-)) 100;
   eq __LOC__ (A.reduceReverse [|1;2|] 100 (-)) 97;
diff --git a/jscomp/test/bs_hashmap_test.js b/jscomp/test/bs_hashmap_test.js
index 15e345c4b0..e7c7a75c1a 100644
--- a/jscomp/test/bs_hashmap_test.js
+++ b/jscomp/test/bs_hashmap_test.js
@@ -1,7 +1,7 @@
 'use strict';
 
 var Mt = require("./mt.js");
-var Bs_Dict = require("../../lib/js/bs_Dict.js");
+var Bs_Id = require("../../lib/js/bs_Id.js");
 var Hashtbl = require("../../lib/js/hashtbl.js");
 var Bs_Array = require("../../lib/js/bs_Array.js");
 var Bs_HashMap = require("../../lib/js/bs_HashMap.js");
@@ -29,7 +29,7 @@ var hash = Hashtbl.hash;
 
 var cmp = Caml_primitive.caml_int_compare;
 
-var Y = Bs_Dict.hashable(hash, eq);
+var Y = Bs_Id.hashable(hash, eq);
 
 var empty = Bs_HashMap.make(30, Y);
 
diff --git a/jscomp/test/bs_hashmap_test.ml b/jscomp/test/bs_hashmap_test.ml
index 920d5f47a1..e3946d3084 100644
--- a/jscomp/test/bs_hashmap_test.ml
+++ b/jscomp/test/bs_hashmap_test.ml
@@ -11,7 +11,7 @@ module S = Bs.Map.Int
 let eq = fun (x : int) y ->  x = y 
 let hash = fun (x : int) ->  Hashtbl.hash x 
 let cmp = fun  (x : int) y -> compare x y
-module Y = (val Bs.Dict.hashable ~eq ~hash)
+module Y = (val Bs.Id.hashable ~eq ~hash)
 let empty : (int, int, _) N.t = N.make ~dict:(module Y) 30 
 
 (*
diff --git a/jscomp/test/bs_hashtbl_string_test.js b/jscomp/test/bs_hashtbl_string_test.js
index 0fdeb094a6..30697eecc7 100644
--- a/jscomp/test/bs_hashtbl_string_test.js
+++ b/jscomp/test/bs_hashtbl_string_test.js
@@ -1,6 +1,6 @@
 'use strict';
 
-var Bs_Dict = require("../../lib/js/bs_Dict.js");
+var Bs_Id = require("../../lib/js/bs_Id.js");
 var Hashtbl = require("../../lib/js/hashtbl.js");
 var Caml_hash = require("../../lib/js/caml_hash.js");
 var Bs_HashMap = require("../../lib/js/bs_HashMap.js");
@@ -27,21 +27,21 @@ var hashString = (function (str) {
                                               }
                                             );
 
-var $$String = Bs_Dict.hashable(Hashtbl.hash, (function (x, y) {
+var $$String = Bs_Id.hashable(Hashtbl.hash, (function (x, y) {
         return +(x === y);
       }));
 
-var String1 = Bs_Dict.hashable(hashString, (function (x, y) {
+var String1 = Bs_Id.hashable(hashString, (function (x, y) {
         return +(x === y);
       }));
 
-var String2 = Bs_Dict.hashable((function (x) {
+var String2 = Bs_Id.hashable((function (x) {
         return Caml_hash.caml_hash_final_mix(Caml_hash.caml_hash_mix_string(0, x));
       }), (function (x, y) {
         return +(x === y);
       }));
 
-var Int = Bs_Dict.hashable(Hashtbl.hash, (function (x, y) {
+var Int = Bs_Id.hashable(Hashtbl.hash, (function (x, y) {
         return +(x === y);
       }));
 
@@ -142,7 +142,7 @@ function bench3(m) {
   }
 }
 
-var Sx = Bs_Dict.comparable(Caml_primitive.caml_string_compare);
+var Sx = Bs_Id.comparable(Caml_primitive.caml_string_compare);
 
 function bench4() {
   var table = Bs_internalBucketsType.make(/* () */0, /* () */0, 1000000);
diff --git a/jscomp/test/bs_hashtbl_string_test.ml b/jscomp/test/bs_hashtbl_string_test.ml
index 268a05da71..dd47575731 100644
--- a/jscomp/test/bs_hashtbl_string_test.ml
+++ b/jscomp/test/bs_hashtbl_string_test.ml
@@ -18,21 +18,21 @@ let hashString : string -> int  = [%raw{|function (str) {
                                             |}]
 
 module String = 
-  (val Bs.Dict.hashable 
+  (val Bs.Id.hashable 
       ~eq:(fun (x:string) y -> x = y )
       ~hash:Hashtbl.hash)
 
 module String1 = 
-  (val Bs.Dict.hashable
+  (val Bs.Id.hashable
       ~eq:(fun (x:string) y -> x = y )
       ~hash:hashString)
 module String2 = 
-  (val Bs.Dict.hashable
+  (val Bs.Id.hashable
       ~eq:(fun (x:string) y -> x = y )
       ~hash:(fun  (x:string) -> hash_string x))
 
 module Int = 
-  (val Bs.Dict.hashable
+  (val Bs.Id.hashable
       ~eq:(fun (x:int) y -> x = y )
       ~hash:Hashtbl.hash)
 module N = Bs.HashMap
@@ -61,7 +61,7 @@ let initial_size = 1_000_000
     #.add (string_of_int i) i
 *)    
 module M = Bs.HashMap
-let bench2 (type t) (m : (string,t) Bs.Dict.hashable) = 
+let bench2 (type t) (m : (string,t) Bs.Id.hashable) = 
   let empty = 
     M.make ~dict:m initial_size in
   let module String = (val m) in     
@@ -84,7 +84,7 @@ let bench2 (type t) (m : (string,t) Bs.Dict.hashable) =
 (* Bs.HashMap.logStats empty *)
 module Md = Bs.Map 
 module Md0 = Bs.Map.Dict
-let bench3 (type t) (m : (string,t) Bs.Dict.comparable) = 
+let bench3 (type t) (m : (string,t) Bs.Id.comparable) = 
   
   let empty = Md.make m in
   let module String = (val m) in 
@@ -104,7 +104,7 @@ let bench3 (type t) (m : (string,t) Bs.Dict.comparable) =
   done ;
   assert (Md0.size !table = 0)
 
-module Sx = (val Bs.Dict.comparable ~cmp:(fun  (x : string) y -> compare x y )) 
+module Sx = (val Bs.Id.comparable ~cmp:(fun  (x : string) y -> compare x y )) 
 module H = Bs.HashMap.String
 let bench4 () = 
   let table = 
diff --git a/jscomp/test/bs_map_set_dict_test.js b/jscomp/test/bs_map_set_dict_test.js
index 14f65168f5..3a6d91a752 100644
--- a/jscomp/test/bs_map_set_dict_test.js
+++ b/jscomp/test/bs_map_set_dict_test.js
@@ -1,8 +1,8 @@
 'use strict';
 
 var Mt = require("./mt.js");
+var Bs_Id = require("../../lib/js/bs_Id.js");
 var Bs_Map = require("../../lib/js/bs_Map.js");
-var Bs_Dict = require("../../lib/js/bs_Dict.js");
 var Bs_List = require("../../lib/js/bs_List.js");
 var Bs_Array = require("../../lib/js/bs_Array.js");
 var Bs_MapInt = require("../../lib/js/bs_MapInt.js");
@@ -23,16 +23,16 @@ function b(loc, v) {
   return Mt.bool_suites(test_id, suites, loc, v);
 }
 
-var Icmp = Bs_Dict.comparable(Caml_primitive.caml_int_compare);
+var Icmp = Bs_Id.comparable(Caml_primitive.caml_int_compare);
 
-var Icmp2 = Bs_Dict.comparable(Caml_primitive.caml_int_compare);
+var Icmp2 = Bs_Id.comparable(Caml_primitive.caml_int_compare);
 
 var m0 = {
   cmp: Icmp[/* cmp */0],
   data: Bs_MapDict.empty
 };
 
-var I2 = Bs_Dict.comparable((function (x, y) {
+var I2 = Bs_Id.comparable((function (x, y) {
         return Caml_primitive.caml_int_compare(y, x);
       }));
 
@@ -48,9 +48,9 @@ var m2 = {
 
 var data = m.data;
 
-Bs_Map.getDict(m2);
+Bs_Map.getId(m2);
 
-var m_dict = Bs_Map.getDict(m);
+var m_dict = Bs_Map.getId(m);
 
 for(var i = 0; i <= 100000; ++i){
   data = Bs_MapDict.set(data, i, i, m_dict[/* cmp */0]);
@@ -74,7 +74,7 @@ var v = {
   data: Bs_SetDict.empty
 };
 
-var m_dict$1 = Bs_Map.getDict(m);
+var m_dict$1 = Bs_Map.getId(m);
 
 var cmp = m_dict$1[/* cmp */0];
 
diff --git a/jscomp/test/bs_map_set_dict_test.ml b/jscomp/test/bs_map_set_dict_test.ml
index 74c0314a3d..dbac0d45c1 100644
--- a/jscomp/test/bs_map_set_dict_test.ml
+++ b/jscomp/test/bs_map_set_dict_test.ml
@@ -4,13 +4,13 @@ let eq loc x y = Mt.eq_suites ~suites ~test_id loc x y
 let b loc v  = Mt.bool_suites ~suites ~test_id loc v 
 
 module Icmp = 
-  (val Bs.Dict.comparable
+  (val Bs.Id.comparable
     ~cmp:(fun (x : int) y -> 
       compare x y
      )
   )
 module Icmp2 = 
-(val Bs.Dict.comparable ~cmp:(fun  (x : int) y ->
+(val Bs.Id.comparable ~cmp:(fun  (x : int) y ->
       compare x y ))
   
 module M = Bs.Map
@@ -23,7 +23,7 @@ let m0 : (_,string,_) M.t = M.make (module Icmp)
 
   
 module I2 = 
-(val Bs.Dict.comparable ~cmp:(fun  (x : int) y -> compare y x ))
+(val Bs.Id.comparable ~cmp:(fun  (x : int) y -> compare y x ))
 
   
 let m = M.make (module Icmp2)
@@ -34,7 +34,7 @@ module Md0 = Bs.Map.Dict
 let () = 
   let count = 1_000_00 in 
   let data = ref (M.getData m) in 
-  let m2_dict, m_dict = M.(getDict m2, getDict m) in 
+  let m2_dict, m_dict = M.(getId m2, getId m) in 
   let module N = (val m2_dict) in 
   let module Mm = ( val m_dict) in
   for i = 0 to count do 
@@ -43,7 +43,7 @@ let () =
       ~cmp:  Mm.cmp
       i i 
   done ;
-  let newm = M.packDictData ~data:!data ~dict:m_dict in 
+  let newm = M.packIdData ~data:!data ~id:m_dict in 
   Js.log newm
 module ISet = Bs.Set 
 let () =     
@@ -59,7 +59,7 @@ module S0 = Bs.Set.Dict
 let () =   
  let count = 100_000 in 
   let v = ISet.make (module Icmp2) in 
-  let m_dict = M.getDict m in 
+  let m_dict = M.getId m in 
   let module M = (val m_dict) in 
   let cmp = M.cmp in 
   let data = ref (ISet.getData v) in 
@@ -68,7 +68,7 @@ let () =
   done ;
   Js.log !data  
 
-let f = M.ofArray ~dict:(module Icmp)
+let f = M.ofArray ~id:(module Icmp)
 let (=~) a b = M.eq a b  
 
 let () =   
diff --git a/jscomp/test/bs_poly_map_test.js b/jscomp/test/bs_poly_map_test.js
index 80690ba6e8..3bf0d2ba85 100644
--- a/jscomp/test/bs_poly_map_test.js
+++ b/jscomp/test/bs_poly_map_test.js
@@ -1,9 +1,9 @@
 'use strict';
 
 var Mt = require("./mt.js");
+var Bs_Id = require("../../lib/js/bs_Id.js");
 var Bs_Map = require("../../lib/js/bs_Map.js");
 var Bs_Set = require("../../lib/js/bs_Set.js");
-var Bs_Dict = require("../../lib/js/bs_Dict.js");
 var Bs_Array = require("../../lib/js/bs_Array.js");
 var Caml_obj = require("../../lib/js/caml_obj.js");
 var Bs_MapDict = require("../../lib/js/bs_MapDict.js");
@@ -22,7 +22,7 @@ function b(loc, v) {
   return Mt.bool_suites(test_id, suites, loc, v);
 }
 
-var Icmp = Bs_Dict.comparable(Caml_primitive.caml_int_compare);
+var Icmp = Bs_Id.comparable(Caml_primitive.caml_int_compare);
 
 function mapOfArray(x) {
   return Bs_Map.ofArray(x, Icmp);
diff --git a/jscomp/test/bs_poly_map_test.ml b/jscomp/test/bs_poly_map_test.ml
index dda5757151..d2e7febde4 100644
--- a/jscomp/test/bs_poly_map_test.ml
+++ b/jscomp/test/bs_poly_map_test.ml
@@ -4,7 +4,7 @@ let eq loc x y = Mt.eq_suites ~suites ~test_id loc x y
 let b loc v  = Mt.bool_suites ~suites ~test_id loc v 
 
 module Icmp = 
-  (val Bs.Dict.comparable 
+  (val Bs.Id.comparable 
       (fun (x : int) y ->  compare x y)
   )
 module M = Bs.Map  
@@ -14,7 +14,7 @@ module A = Bs_Array
 module I = Array_data_util
 
 
-let mapOfArray x = M.ofArray ~dict:(module Icmp) x 
+let mapOfArray x = M.ofArray ~id:(module Icmp) x 
 let setOfArray x = N.ofArray ~dict:(module Icmp) x 
 let emptyMap () = M.make (module Icmp)
 
diff --git a/jscomp/test/bs_poly_mutable_map_test.js b/jscomp/test/bs_poly_mutable_map_test.js
index eb88b42cf8..994478ba0c 100644
--- a/jscomp/test/bs_poly_mutable_map_test.js
+++ b/jscomp/test/bs_poly_mutable_map_test.js
@@ -1,8 +1,8 @@
 'use strict';
 
 var Mt = require("./mt.js");
+var Bs_Id = require("../../lib/js/bs_Id.js");
 var Bs_Set = require("../../lib/js/bs_Set.js");
-var Bs_Dict = require("../../lib/js/bs_Dict.js");
 var Bs_Array = require("../../lib/js/bs_Array.js");
 var Bs_MutableMap = require("../../lib/js/bs_MutableMap.js");
 var Caml_primitive = require("../../lib/js/caml_primitive.js");
@@ -21,7 +21,7 @@ function b(loc, v) {
   return Mt.bool_suites(test_id, suites, loc, v);
 }
 
-var Icmp = Bs_Dict.comparable(Caml_primitive.caml_int_compare);
+var Icmp = Bs_Id.comparable(Caml_primitive.caml_int_compare);
 
 function f(x) {
   return Bs_MutableMap.ofArray(x, Icmp);
diff --git a/jscomp/test/bs_poly_mutable_map_test.ml b/jscomp/test/bs_poly_mutable_map_test.ml
index f1cc50a6ef..09ec758dfe 100644
--- a/jscomp/test/bs_poly_mutable_map_test.ml
+++ b/jscomp/test/bs_poly_mutable_map_test.ml
@@ -4,7 +4,7 @@ let eq loc x y = Mt.eq_suites ~suites ~test_id loc x y
 let b loc v  = Mt.bool_suites ~suites ~test_id loc v 
 
 module Icmp = 
-  (val Bs.Dict.comparable 
+  (val Bs.Id.comparable 
       (fun (x : int) y ->  compare x y
       )
   )
diff --git a/jscomp/test/bs_poly_mutable_set_test.js b/jscomp/test/bs_poly_mutable_set_test.js
index 69da7caa3e..c56216bfb7 100644
--- a/jscomp/test/bs_poly_mutable_set_test.js
+++ b/jscomp/test/bs_poly_mutable_set_test.js
@@ -1,7 +1,7 @@
 'use strict';
 
 var Mt = require("./mt.js");
-var Bs_Dict = require("../../lib/js/bs_Dict.js");
+var Bs_Id = require("../../lib/js/bs_Id.js");
 var Bs_List = require("../../lib/js/bs_List.js");
 var Bs_Array = require("../../lib/js/bs_Array.js");
 var Caml_obj = require("../../lib/js/caml_obj.js");
@@ -22,7 +22,7 @@ function b(loc, x) {
   return Mt.bool_suites(test_id, suites, loc, x);
 }
 
-var IntCmp = Bs_Dict.comparable(Caml_primitive.caml_int_compare);
+var IntCmp = Bs_Id.comparable(Caml_primitive.caml_int_compare);
 
 function ofArray(param) {
   return Bs_MutableSet.ofArray(param, IntCmp);
diff --git a/jscomp/test/bs_poly_mutable_set_test.ml b/jscomp/test/bs_poly_mutable_set_test.ml
index ee68b85f83..b746feca12 100644
--- a/jscomp/test/bs_poly_mutable_set_test.ml
+++ b/jscomp/test/bs_poly_mutable_set_test.ml
@@ -7,7 +7,7 @@ module N = Bs.MutableSet
 module I = Array_data_util
 module A = Bs.Array
 module IntCmp = 
-  (val Bs.Dict.comparable (fun (x:int) y -> compare x y))
+  (val Bs.Id.comparable (fun (x:int) y -> compare x y))
 module L = Bs.List
 let ofArray = N.ofArray ~dict:(module IntCmp)
 let empty () = N.make ~dict:(module IntCmp)
diff --git a/jscomp/test/bs_poly_set_test.js b/jscomp/test/bs_poly_set_test.js
index 854c97fe0f..f0089b767f 100644
--- a/jscomp/test/bs_poly_set_test.js
+++ b/jscomp/test/bs_poly_set_test.js
@@ -1,8 +1,8 @@
 'use strict';
 
 var Mt = require("./mt.js");
+var Bs_Id = require("../../lib/js/bs_Id.js");
 var Bs_Set = require("../../lib/js/bs_Set.js");
-var Bs_Dict = require("../../lib/js/bs_Dict.js");
 var Bs_List = require("../../lib/js/bs_List.js");
 var Bs_Array = require("../../lib/js/bs_Array.js");
 var Caml_obj = require("../../lib/js/caml_obj.js");
@@ -26,7 +26,7 @@ function t(loc, x) {
   return Mt.throw_suites(test_id, suites, loc, x);
 }
 
-var IntCmp = Bs_Dict.comparable(Caml_primitive.caml_int_compare);
+var IntCmp = Bs_Id.comparable(Caml_primitive.caml_int_compare);
 
 var u0 = Bs_Set.ofArray(Array_data_util.range(0, 30), IntCmp);
 
diff --git a/jscomp/test/bs_poly_set_test.ml b/jscomp/test/bs_poly_set_test.ml
index 9ece6424c0..6085130118 100644
--- a/jscomp/test/bs_poly_set_test.ml
+++ b/jscomp/test/bs_poly_set_test.ml
@@ -7,7 +7,7 @@ module N = Bs.Set
 module I = Array_data_util
 module A = Bs.Array
 module IntCmp = 
-  (val Bs.Dict.comparable (fun (x:int) y -> compare x y))
+  (val Bs.Id.comparable (fun (x:int) y -> compare x y))
 module L = Bs.List
 
 let () = 
diff --git a/lib/js/bs.js b/lib/js/bs.js
index 2588aee4d0..50a1edc580 100644
--- a/lib/js/bs.js
+++ b/lib/js/bs.js
@@ -1,7 +1,7 @@
 'use strict';
 
 
-var Dict = 0;
+var Id = 0;
 
 var $$Array = 0;
 
@@ -27,7 +27,7 @@ var HashSet = 0;
 
 var HashMap = 0;
 
-exports.Dict = Dict;
+exports.Id = Id;
 exports.$$Array = $$Array;
 exports.SortArray = SortArray;
 exports.MutableQueue = MutableQueue;
diff --git a/lib/js/bs_Array.js b/lib/js/bs_Array.js
index 62e09bf3b7..5b14f63e14 100644
--- a/lib/js/bs_Array.js
+++ b/lib/js/bs_Array.js
@@ -124,6 +124,35 @@ function makeByAndShuffle(l, f) {
   return makeByAndShuffleU(l, Curry.__1(f));
 }
 
+function range(start, finish) {
+  var cut = finish - start | 0;
+  if (cut < 0) {
+    return /* int array */[];
+  } else {
+    var arr = new Array(cut + 1 | 0);
+    for(var i = 0; i <= cut; ++i){
+      arr[i] = start + i | 0;
+    }
+    return arr;
+  }
+}
+
+function rangeBy(start, finish, step) {
+  var cut = finish - start | 0;
+  if (cut < 0 || step <= 0) {
+    return /* int array */[];
+  } else {
+    var nb = (cut / step | 0) + 1 | 0;
+    var arr = new Array(nb);
+    var cur = start;
+    for(var i = 0 ,i_finish = nb - 1 | 0; i <= i_finish; ++i){
+      arr[i] = cur;
+      cur = cur + step | 0;
+    }
+    return arr;
+  }
+}
+
 function zip(xs, ys) {
   var lenx = xs.length;
   var leny = ys.length;
@@ -526,6 +555,8 @@ exports.shuffle = shuffle;
 exports.reverseInPlace = reverseInPlace;
 exports.reverse = reverse;
 exports.make = make;
+exports.range = range;
+exports.rangeBy = rangeBy;
 exports.makeByU = makeByU;
 exports.makeBy = makeBy;
 exports.makeByAndShuffleU = makeByAndShuffleU;
diff --git a/lib/js/bs_Id.js b/lib/js/bs_Id.js
new file mode 100644
index 0000000000..636adfdb7e
--- /dev/null
+++ b/lib/js/bs_Id.js
@@ -0,0 +1,28 @@
+'use strict';
+
+var Curry = require("./curry.js");
+
+function comparableU(cmp) {
+  return /* module */[/* cmp */cmp];
+}
+
+function comparable(cmp) {
+  return comparableU(Curry.__2(cmp));
+}
+
+function hashableU(hash, eq) {
+  return /* module */[
+          /* hash */hash,
+          /* eq */eq
+        ];
+}
+
+function hashable(hash, eq) {
+  return hashableU(Curry.__1(hash), Curry.__2(eq));
+}
+
+exports.comparableU = comparableU;
+exports.comparable = comparable;
+exports.hashableU = hashableU;
+exports.hashable = hashable;
+/* No side effect */
diff --git a/lib/js/bs_Map.js b/lib/js/bs_Map.js
index 8bf6e2e0be..bfc74064d9 100644
--- a/lib/js/bs_Map.js
+++ b/lib/js/bs_Map.js
@@ -3,8 +3,8 @@
 var Curry = require("./curry.js");
 var Bs_MapDict = require("./bs_MapDict.js");
 
-function ofArray(data, dict) {
-  var cmp = dict[/* cmp */0];
+function ofArray(data, id) {
+  var cmp = id[/* cmp */0];
   return {
           cmp: cmp,
           data: Bs_MapDict.ofArray(data, cmp)
@@ -94,9 +94,9 @@ function merge(s1, s2, f) {
   return mergeU(s1, s2, Curry.__3(f));
 }
 
-function make(dict) {
+function make(id) {
   return {
-          cmp: dict[/* cmp */0],
+          cmp: id[/* cmp */0],
           data: Bs_MapDict.empty
         };
 }
@@ -285,14 +285,14 @@ function getData(prim) {
   return prim.data;
 }
 
-function getDict(m) {
+function getId(m) {
   var cmp = m.cmp;
   return /* module */[/* cmp */cmp];
 }
 
-function packDictData(dict, data) {
+function packIdData(id, data) {
   return {
-          cmp: dict[/* cmp */0],
+          cmp: id[/* cmp */0],
           data: data
         };
 }
@@ -357,7 +357,7 @@ exports.mapU = mapU;
 exports.map = map;
 exports.mapWithKeyU = mapWithKeyU;
 exports.mapWithKey = mapWithKey;
-exports.getDict = getDict;
+exports.getId = getId;
 exports.getData = getData;
-exports.packDictData = packDictData;
+exports.packIdData = packIdData;
 /* No side effect */
diff --git a/lib/js/bs_Range.js b/lib/js/bs_Range.js
index fee0c81dcd..6fb5ea2e02 100644
--- a/lib/js/bs_Range.js
+++ b/lib/js/bs_Range.js
@@ -32,19 +32,27 @@ function every(s, f, p) {
   return everyU(s, f, Curry.__1(p));
 }
 
-function everyByU(_s, f, step, p) {
-  while(true) {
-    var s = _s;
-    if (s > f) {
-      return /* true */1;
-    } else if (p(s)) {
-      _s = s + step | 0;
-      continue ;
-      
-    } else {
-      return /* false */0;
-    }
-  };
+function everyByU(s, f, step, p) {
+  if (step > 0) {
+    var _s = s;
+    var f$1 = f;
+    var step$1 = step;
+    var p$1 = p;
+    while(true) {
+      var s$1 = _s;
+      if (s$1 > f$1) {
+        return /* true */1;
+      } else if (p$1(s$1)) {
+        _s = s$1 + step$1 | 0;
+        continue ;
+        
+      } else {
+        return /* false */0;
+      }
+    };
+  } else {
+    return /* true */1;
+  }
 }
 
 function everyBy(s, f, step, p) {
@@ -70,19 +78,27 @@ function some(s, f, p) {
   return someU(s, f, Curry.__1(p));
 }
 
-function someByU(_s, f, step, p) {
-  while(true) {
-    var s = _s;
-    if (s > f) {
-      return /* false */0;
-    } else if (p(s)) {
-      return /* true */1;
-    } else {
-      _s = s + step | 0;
-      continue ;
-      
-    }
-  };
+function someByU(s, f, step, p) {
+  if (step > 0) {
+    var _s = s;
+    var f$1 = f;
+    var step$1 = step;
+    var p$1 = p;
+    while(true) {
+      var s$1 = _s;
+      if (s$1 > f$1) {
+        return /* false */0;
+      } else if (p$1(s$1)) {
+        return /* true */1;
+      } else {
+        _s = s$1 + step$1 | 0;
+        continue ;
+        
+      }
+    };
+  } else {
+    return /* false */0;
+  }
 }
 
 function someBy(s, f, step, p) {