diff --git a/jscomp/core/j.ml b/jscomp/core/j.ml
index 401a0ab826..00316f9ef2 100644
--- a/jscomp/core/j.ml
+++ b/jscomp/core/j.ml
@@ -305,8 +305,8 @@ and statement_desc =
     {[ goto : label option ; ]}
   *)
 
-  | Int_switch of expression * int case_clause list * block option 
-  | String_switch of expression * string case_clause list * block option 
+  | Int_switch of expression * int_clause list * block option 
+  | String_switch of expression * string_clause list * block option 
   | Throw of expression
   | Try of block * (exception_ident * block) option * block option
   | Debugger
@@ -329,9 +329,9 @@ and variable_declaration = {
   property : property;
   ident_info : ident_info;
 }
-
-and 'a case_clause = { 
-  switch_case : 'a ; 
+and string_clause = string * case_clause
+and int_clause =  int * case_clause
+and case_clause = {   
   switch_body : block ;
   should_break :  bool ;  (* true means break *)
   comment : string option ;
diff --git a/jscomp/core/js_dump.ml b/jscomp/core/js_dump.ml
index 23a4826ec5..aab33c9c37 100644
--- a/jscomp/core/js_dump.ml
+++ b/jscomp/core/js_dump.ml
@@ -488,9 +488,9 @@ and  pp_function ~is_method
     since it can be either [int] or [string]
 *)
 and pp_one_case_clause : 'a .
-  _ -> P.t -> (P.t -> 'a -> unit) -> 'a J.case_clause -> _
+  _ -> P.t -> (P.t -> 'a -> unit) -> ('a * J.case_clause) -> _
   = fun cxt f  pp_cond
-    ({switch_case; switch_body ; should_break; comment; } : _ J.case_clause) ->
+    (switch_case, ({switch_body ; should_break; comment; } :  J.case_clause)) ->
     let cxt =
       P.group f 1  (fun _ ->
           P.group f 1 (fun _ ->
@@ -520,7 +520,7 @@ and pp_one_case_clause : 'a .
     cxt
 
 and loop_case_clauses  :  'a . cxt ->
-  P.t -> (P.t -> 'a -> unit) -> 'a J.case_clause list -> cxt
+  P.t -> (P.t -> 'a -> unit) -> ('a * J.case_clause) list -> cxt
   = fun  cxt  f pp_cond cases ->
     Ext_list.fold_left cases cxt (fun acc x -> pp_one_case_clause acc f pp_cond x)              
 
diff --git a/jscomp/core/js_fold.ml b/jscomp/core/js_fold.ml
index a844d573d9..fc99953b7c 100644
--- a/jscomp/core/js_fold.ml
+++ b/jscomp/core/js_fold.ml
@@ -47,6 +47,9 @@ class virtual fold =
         let o = o#option (fun o -> o#expression) _x_i1 in
         let o = o#property _x_i2 in let o = o#ident_info _x_i3 in o
     method tag_info : tag_info -> 'self_type = o#unknown
+    method string_clause : string_clause -> 'self_type =
+      fun (_x, _x_i1) ->
+        let o = o#string _x in let o = o#case_clause _x_i1 in o
     method statement_desc : statement_desc -> 'self_type =
       function
       | Block _x -> let o = o#block _x in o
@@ -70,10 +73,28 @@ class virtual fold =
       | Return _x -> let o = o#expression _x in o
       | Int_switch (_x, _x_i1, _x_i2) ->
           let o = o#expression _x in
+          let o = o#list (fun o -> o#int_clause) _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | String_switch (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#list (fun o -> o#string_clause) _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | Throw _x -> let o = o#expression _x in o
+      | Try (_x, _x_i1, _x_i2) ->
+          let o = o#block _x in
           let o =
-            o#list
-              (fun o ->
-                 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+            o#option
+              (fun o (_x, _x_i1) ->
+                 let o = o#exception_ident _x in let o = o#block _x_i1 in o)
+              _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | Debugger -> o
+    method statement : statement -> 'self_type =
+      fun { statement_desc = _x; comment = _x_i1 } ->
+        let o = o#statement_desc _x in
+        let o = o#option (fun o -> o#string) _x_i1 in o
+    method required_modules : required_modules -> 'self_type =
+      (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
  * 
  * 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
@@ -96,7 +117,7 @@ class virtual fold =
  * 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. *)
-                 (* Javascript IR
+      (* Javascript IR
   
     It's a subset of Javascript AST specialized for OCaml lambda backend
 
@@ -104,15 +125,18 @@ class virtual fold =
     convention and [Block] is just a sequence of statements, which means it does 
     not introduce new scope
 *)
-                 (* TODO: it seems that camlp4of supports very limited structures
+      (* TODO: it seems that camlp4of supports very limited structures
    it does not even support attributes like `[@@@warning "-30"]
    we should get rid of such dependency ASAP
 *)
-                 (** object literal, if key is ident, in this case, it might be renamed by 
+      o#list (fun o -> o#module_id)
+    method property_name : property_name -> 'self_type = o#unknown
+    method property_map : property_map -> 'self_type =
+      (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-                 (* Since camldot is only available for toplevel module accessors,
+      (* Since camldot is only available for toplevel module accessors,
        we don't need print  `A.length$2`
        just print `A.length` - it's guarateed to be unique
        
@@ -127,7 +151,74 @@ class virtual fold =
          Qualified (_, Runtime, Some "caml_int_compare")         
        ]}       
      *)
-                 (** where we use a trick [== null ] *) (* js true/false*)
+      o#list
+        (fun o (_x, _x_i1) ->
+           let o = o#property_name _x in let o = o#expression _x_i1 in o)
+    method property : property -> 'self_type = o#unknown
+    method program : program -> 'self_type =
+      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
+        let o = o#block _x in
+        let o = o#exports _x_i1 in let o = o#unknown _x_i2 in o
+    method number : number -> 'self_type = o#unknown
+    method mutable_flag : mutable_flag -> 'self_type = o#unknown
+    method module_id : module_id -> 'self_type =
+      fun { id = _x; kind = _x_i1 } ->
+        let o = o#ident _x in let o = o#unknown _x_i1 in o
+    method length_object : length_object -> 'self_type = o#unknown
+    method label : label -> 'self_type = o#string
+    method kind : kind -> 'self_type = o#unknown
+    method jsint : jsint -> 'self_type = o#int32
+    method int_op : int_op -> 'self_type = o#unknown
+    method int_clause : int_clause -> 'self_type =
+      fun (_x, _x_i1) -> let o = o#int _x in let o = o#case_clause _x_i1 in o
+    method ident_info : ident_info -> 'self_type = o#unknown
+    method ident : ident -> 'self_type = o#unknown
+    method for_ident_expression : for_ident_expression -> 'self_type =
+      o#expression
+    method for_ident : for_ident -> 'self_type = o#ident
+    method for_direction : for_direction -> 'self_type = o#unknown
+    method finish_ident_expression : finish_ident_expression -> 'self_type =
+      o#expression
+    method expression_desc : expression_desc -> 'self_type =
+      function
+      | Length (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#length_object _x_i1 in o
+      | Char_of_int _x -> let o = o#expression _x in o
+      | Char_to_int _x -> let o = o#expression _x in o
+      | Is_null_or_undefined _x -> let o = o#expression _x in o
+      | String_append (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Bool _x -> let o = o#bool _x in o
+      | Typeof _x -> let o = o#expression _x in o
+      | Js_not _x -> let o = o#expression _x in o
+      | Seq (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Cond (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
+      | Bin (_x, _x_i1, _x_i2) ->
+          let o = o#binop _x in
+          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
+      | FlatCall (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Call (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#list (fun o -> o#expression) _x_i1 in
+          let o = o#unknown _x_i2 in o
+      | String_index (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Array_index (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Static_index (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#string _x_i1 in
+          let o = o#option (fun o -> o#int32) _x_i2 in o
+      | New (_x, _x_i1) ->
+          let o = o#expression _x in
+          let o =
+            o#option
+              (fun o -> (** where we use a trick [== null ] *)
+                 (* js true/false*)
                  (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence 
      [typeof] is an operator     
   *)
@@ -162,11 +253,52 @@ class virtual fold =
           All exported declarations have to be OCaml identifiers
        2. Javascript dot (need to be preserved/or using quote)
      *)
-                 (* TODO: option remove *)
-                 (* The first parameter by default is false, 
+                 o#list (fun o -> o#expression))
+              _x_i1
+          in o
+      | Var _x -> let o = o#vident _x in o
+      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
+          let o = o#bool _x in
+          let o = o#list (fun o -> o#ident) _x_i1 in
+          let o = o#block _x_i2 in let o = o#unknown _x_i3 in o
+      | Str (_x, _x_i1) -> let o = o#bool _x in let o = o#string _x_i1 in o
+      | Unicode _x -> let o = o#string _x in o
+      | Raw_js_code _x -> let o = o#unknown _x in o
+      | Array (_x, _x_i1) ->
+          let o = o#list (fun o -> o#expression) _x in
+          let o = o#mutable_flag _x_i1 in o
+      | Optional_block (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#bool _x_i1 in o
+      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
+          let o = o#list (fun o -> o#expression) _x in
+          let o = o#mutable_flag _x_i1 in
+          let o = o#expression _x_i2 in let o = o#tag_info _x_i3 in o
+      | Caml_block_tag _x -> let o = o#expression _x in o
+      | Number _x -> let o = o#number _x in o
+      | Object _x -> let o = o#property_map _x in o
+      | Undefined -> o
+      | Null -> o
+    method expression : expression -> 'self_type =
+      fun { expression_desc = _x; comment = _x_i1 } ->
+        let o = o#expression_desc _x in
+        let o = o#option (fun o -> o#string) _x_i1 in o
+    method exports : exports -> 'self_type = o#unknown
+    method exception_ident : exception_ident -> 'self_type = o#ident
+    method deps_program : deps_program -> 'self_type =
+      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
+        let o = o#program _x in
+        let o = o#required_modules _x_i1 in
+        let o = o#option (fun o -> o#string) _x_i2 in o
+    method case_clause : case_clause -> 'self_type =
+      fun { switch_body = _x; should_break = _x_i1; comment = _x_i2 } ->
+        let o = o#block _x in
+        let o = o#bool _x_i1 in
+        let o = o#option (fun o -> o#string) _x_i2 in o
+    method block : block -> 'self_type = (* TODO: option remove *)
+      (* The first parameter by default is false, 
      it will be true when it's a method
   *)
-                 (* A string is UTF-8 encoded, the string may contain
+      (* A string is UTF-8 encoded, the string may contain
        escape sequences.
        The first argument is used to mark it is non-pure, please
        don't optimize it, since it does have side effec, 
@@ -174,13 +306,13 @@ class virtual fold =
        which is better to leave it alone
        The last argument is passed from as `j` from `{j||j}`
      *)
-                 (* It is escaped string, print delimited by '"'*)
-                 (* literally raw JS code 
+      (* It is escaped string, print delimited by '"'*)
+      (* literally raw JS code 
   *) (* [true] means [identity] *)
-                 (* The third argument is [tag] , forth is [tag_info] *)
-                 (* | Caml_uninitialized_obj of expression * expression *)
-                 (* [tag] and [size] tailed  for [Obj.new_block] *)
-                 (* For setter, it still return the value of expression, 
+      (* The third argument is [tag] , forth is [tag_info] *)
+      (* | Caml_uninitialized_obj of expression * expression *)
+      (* [tag] and [size] tailed  for [Obj.new_block] *)
+      (* For setter, it still return the value of expression, 
      we can not use 
      {[
        type 'a access = Get | Set of 'a
@@ -189,20 +321,20 @@ class virtual fold =
      [Caml_block_tag] can return [undefined], 
      you have to use [E.tag] in a safe way     
   *)
-                 (* | Caml_block_set_tag of expression * expression *)
-                 (* | Caml_block_set_length of expression * expression *)
-                 (* It will just fetch tag, to make it safe, when creating it, 
+      (* | Caml_block_set_tag of expression * expression *)
+      (* | Caml_block_set_length of expression * expression *)
+      (* It will just fetch tag, to make it safe, when creating it, 
      we need apply "|0", we don't do it in the 
      last step since "|0" can potentially be optimized
   *)
-                 (* pure*) (* pure *)
-                 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
+      (* pure*) (* pure *)
+      (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
    block can be nested, specified in ES3 
  *)
-                 (* Delay some units like [primitive] into JS layer ,
+      (* Delay some units like [primitive] into JS layer ,
    benefit: better cross module inlining, and smaller IR size?
  *)
-                 (* 
+      (* 
   [closure] captured loop mutable values in the outer loop
 
   check if it contains loop mutable values, happens in nested loop
@@ -228,7 +360,7 @@ class virtual fold =
   contains a block side effect
   TODO: create such example
 *)
-                 (* Since in OCaml, 
+      (* Since in OCaml, 
    
   [for i = 0 to k end do done ]
   k is only evaluated once , to encode this invariant in JS IR,
@@ -237,7 +369,7 @@ class virtual fold =
   TODO: currently we guarantee that [bound] was only 
   excecuted once, should encode this in AST level
 *)
-                 (* Can be simplified to keep the semantics of OCaml
+      (* Can be simplified to keep the semantics of OCaml
    For (var i, e, ...){
      let  j = ... 
    }
@@ -249,7 +381,7 @@ class virtual fold =
      })(i)
    }
 *)
-                 (* Single return is good for ininling..
+      (* Single return is good for ininling..
    However, when you do tail-call optmization
    you loose the expression oriented semantics
    Block is useful for implementing goto
@@ -259,12 +391,12 @@ class virtual fold =
    }
    ]}
 *)
-                 (* Function declaration and Variable declaration  *)
-                 (* check if it contains loop mutable values, happens in nested loop *)
-                 (* only used when inline a fucntion *)
-                 (* Here we need track back a bit ?, move Return to Function ...
+      (* Function declaration and Variable declaration  *)
+      (* check if it contains loop mutable values, happens in nested loop *)
+      (* only used when inline a fucntion *)
+      (* Here we need track back a bit ?, move Return to Function ...
                               Then we can only have one Return, which is not good *)
-                 (* since in ocaml, it's expression oriented langauge, [return] in
+      (* since in ocaml, it's expression oriented langauge, [return] in
     general has no jumps, it only happens when we do 
     tailcall conversion, in that case there is a jump.
     However, currently  a single [break] is good to cover
@@ -274,143 +406,7 @@ class virtual fold =
     A more robust signature would be 
     {[ goto : label option ; ]}
   *)
-                 o#case_clause (fun o -> o#int))
-              _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | String_switch (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o =
-            o#list (fun o -> o#case_clause (fun o -> o#string)) _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | Throw _x -> let o = o#expression _x in o
-      | Try (_x, _x_i1, _x_i2) ->
-          let o = o#block _x in
-          let o =
-            o#option
-              (fun o (_x, _x_i1) ->
-                 let o = o#exception_ident _x in let o = o#block _x_i1 in o)
-              _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | Debugger -> o
-    method statement : statement -> 'self_type =
-      fun { statement_desc = _x; comment = _x_i1 } ->
-        let o = o#statement_desc _x in
-        let o = o#option (fun o -> o#string) _x_i1 in o
-    method required_modules : required_modules -> 'self_type =
-      o#list (fun o -> o#module_id)
-    method property_name : property_name -> 'self_type = o#unknown
-    method property_map : property_map -> 'self_type =
-      o#list
-        (fun o (_x, _x_i1) ->
-           let o = o#property_name _x in let o = o#expression _x_i1 in o)
-    method property : property -> 'self_type = o#unknown
-    method program : program -> 'self_type =
-      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
-        let o = o#block _x in
-        let o = o#exports _x_i1 in let o = o#unknown _x_i2 in o
-    method number : number -> 'self_type = o#unknown
-    method mutable_flag : mutable_flag -> 'self_type = o#unknown
-    method module_id : module_id -> 'self_type =
-      fun { id = _x; kind = _x_i1 } ->
-        let o = o#ident _x in let o = o#unknown _x_i1 in o
-    method length_object : length_object -> 'self_type = o#unknown
-    method label : label -> 'self_type = o#string
-    method kind : kind -> 'self_type = o#unknown
-    method jsint : jsint -> 'self_type = o#int32
-    method int_op : int_op -> 'self_type = o#unknown
-    method ident_info : ident_info -> 'self_type = o#unknown
-    method ident : ident -> 'self_type = o#unknown
-    method for_ident_expression : for_ident_expression -> 'self_type =
-      o#expression
-    method for_ident : for_ident -> 'self_type = o#ident
-    method for_direction : for_direction -> 'self_type = o#unknown
-    method finish_ident_expression : finish_ident_expression -> 'self_type =
-      o#expression
-    method expression_desc : expression_desc -> 'self_type =
-      function
-      | Length (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#length_object _x_i1 in o
-      | Char_of_int _x -> let o = o#expression _x in o
-      | Char_to_int _x -> let o = o#expression _x in o
-      | Is_null_or_undefined _x -> let o = o#expression _x in o
-      | String_append (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Bool _x -> let o = o#bool _x in o
-      | Typeof _x -> let o = o#expression _x in o
-      | Js_not _x -> let o = o#expression _x in o
-      | Seq (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Cond (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
-      | Bin (_x, _x_i1, _x_i2) ->
-          let o = o#binop _x in
-          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
-      | FlatCall (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Call (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#list (fun o -> o#expression) _x_i1 in
-          let o = o#unknown _x_i2 in o
-      | String_index (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Array_index (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Static_index (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#string _x_i1 in
-          let o = o#option (fun o -> o#int32) _x_i2 in o
-      | New (_x, _x_i1) ->
-          let o = o#expression _x in
-          let o = o#option (fun o -> o#list (fun o -> o#expression)) _x_i1
-          in o
-      | Var _x -> let o = o#vident _x in o
-      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
-          let o = o#bool _x in
-          let o = o#list (fun o -> o#ident) _x_i1 in
-          let o = o#block _x_i2 in let o = o#unknown _x_i3 in o
-      | Str (_x, _x_i1) -> let o = o#bool _x in let o = o#string _x_i1 in o
-      | Unicode _x -> let o = o#string _x in o
-      | Raw_js_code _x -> let o = o#unknown _x in o
-      | Array (_x, _x_i1) ->
-          let o = o#list (fun o -> o#expression) _x in
-          let o = o#mutable_flag _x_i1 in o
-      | Optional_block (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#bool _x_i1 in o
-      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
-          let o = o#list (fun o -> o#expression) _x in
-          let o = o#mutable_flag _x_i1 in
-          let o = o#expression _x_i2 in let o = o#tag_info _x_i3 in o
-      | Caml_block_tag _x -> let o = o#expression _x in o
-      | Number _x -> let o = o#number _x in o
-      | Object _x -> let o = o#property_map _x in o
-      | Undefined -> o
-      | Null -> o
-    method expression : expression -> 'self_type =
-      fun { expression_desc = _x; comment = _x_i1 } ->
-        let o = o#expression_desc _x in
-        let o = o#option (fun o -> o#string) _x_i1 in o
-    method exports : exports -> 'self_type = o#unknown
-    method exception_ident : exception_ident -> 'self_type = o#ident
-    method deps_program : deps_program -> 'self_type =
-      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
-        let o = o#program _x in
-        let o = o#required_modules _x_i1 in
-        let o = o#option (fun o -> o#string) _x_i2 in o
-    method case_clause :
-      'a. ('self_type -> 'a -> 'self_type) -> 'a case_clause -> 'self_type =
-      fun _f_a
-        {
-          switch_case = _x;
-          switch_body = _x_i1;
-          should_break = _x_i2;
-          comment = _x_i3
-        } ->
-        let o = _f_a o _x in
-        let o = o#block _x_i1 in
-        let o = o#bool _x_i2 in
-        let o = o#option (fun o -> o#string) _x_i3 in o
-    method block : block -> 'self_type = (* true means break *)
+      (* true means break *)
       (* TODO: For efficency: block should not be a list, it should be able to 
    be concatenated in both ways 
  *)
diff --git a/jscomp/core/js_map.ml b/jscomp/core/js_map.ml
index d7ff54da2b..902889b444 100644
--- a/jscomp/core/js_map.ml
+++ b/jscomp/core/js_map.ml
@@ -56,6 +56,10 @@ class virtual map =
           { ident = _x; value = _x_i1; property = _x_i2; ident_info = _x_i3;
           }
     method tag_info : tag_info -> tag_info = o#unknown
+    method string_clause : string_clause -> string_clause =
+      fun (_x, _x_i1) ->
+        let _x = o#string _x in
+        let _x_i1 = o#case_clause _x_i1 in (_x, _x_i1)
     method statement_desc : statement_desc -> statement_desc =
       function
       | Block _x -> let _x = o#block _x in Block _x
@@ -83,10 +87,33 @@ class virtual map =
       | Return _x -> let _x = o#expression _x in Return _x
       | Int_switch (_x, _x_i1, _x_i2) ->
           let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#int_clause) _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in Int_switch (_x, _x_i1, _x_i2)
+      | String_switch (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#string_clause) _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in String_switch (_x, _x_i1, _x_i2)
+      | Throw _x -> let _x = o#expression _x in Throw _x
+      | Try (_x, _x_i1, _x_i2) ->
+          let _x = o#block _x in
           let _x_i1 =
-            o#list
-              (fun o ->
-                 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+            o#option
+              (fun o (_x, _x_i1) ->
+                 let _x = o#exception_ident _x in
+                 let _x_i1 = o#block _x_i1 in (_x, _x_i1))
+              _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in Try (_x, _x_i1, _x_i2)
+      | Debugger -> Debugger
+    method statement : statement -> statement =
+      fun { statement_desc = _x; comment = _x_i1 } ->
+        let _x = o#statement_desc _x in
+        let _x_i1 = o#option (fun o -> o#string) _x_i1
+        in { statement_desc = _x; comment = _x_i1; }
+    method required_modules : required_modules -> required_modules =
+      (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
  * 
  * 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
@@ -109,7 +136,7 @@ class virtual map =
  * 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. *)
-                 (* Javascript IR
+      (* Javascript IR
   
     It's a subset of Javascript AST specialized for OCaml lambda backend
 
@@ -117,15 +144,18 @@ class virtual map =
     convention and [Block] is just a sequence of statements, which means it does 
     not introduce new scope
 *)
-                 (* TODO: it seems that camlp4of supports very limited structures
+      (* TODO: it seems that camlp4of supports very limited structures
    it does not even support attributes like `[@@@warning "-30"]
    we should get rid of such dependency ASAP
 *)
-                 (** object literal, if key is ident, in this case, it might be renamed by 
+      o#list (fun o -> o#module_id)
+    method property_name : property_name -> property_name = o#unknown
+    method property_map : property_map -> property_map =
+      (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-                 (* Since camldot is only available for toplevel module accessors,
+      (* Since camldot is only available for toplevel module accessors,
        we don't need print  `A.length$2`
        just print `A.length` - it's guarateed to be unique
        
@@ -140,7 +170,89 @@ class virtual map =
          Qualified (_, Runtime, Some "caml_int_compare")         
        ]}       
      *)
-                 (** where we use a trick [== null ] *) (* js true/false*)
+      o#list
+        (fun o (_x, _x_i1) ->
+           let _x = o#property_name _x in
+           let _x_i1 = o#expression _x_i1 in (_x, _x_i1))
+    method property : property -> property = o#unknown
+    method program : program -> program =
+      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
+        let _x = o#block _x in
+        let _x_i1 = o#exports _x_i1 in
+        let _x_i2 = o#unknown _x_i2
+        in { block = _x; exports = _x_i1; export_set = _x_i2; }
+    method number : number -> number = o#unknown
+    method mutable_flag : mutable_flag -> mutable_flag = o#unknown
+    method module_id : module_id -> module_id =
+      fun { id = _x; kind = _x_i1 } ->
+        let _x = o#ident _x in
+        let _x_i1 = o#unknown _x_i1 in { id = _x; kind = _x_i1; }
+    method length_object : length_object -> length_object = o#unknown
+    method label : label -> label = o#string
+    method kind : kind -> kind = o#unknown
+    method jsint : jsint -> jsint = o#int32
+    method int_op : int_op -> int_op = o#unknown
+    method int_clause : int_clause -> int_clause =
+      fun (_x, _x_i1) ->
+        let _x = o#int _x in let _x_i1 = o#case_clause _x_i1 in (_x, _x_i1)
+    method ident_info : ident_info -> ident_info = o#unknown
+    method ident : ident -> ident = o#unknown
+    method for_ident_expression :
+      for_ident_expression -> for_ident_expression = o#expression
+    method for_ident : for_ident -> for_ident = o#ident
+    method for_direction : for_direction -> for_direction = o#unknown
+    method finish_ident_expression :
+      finish_ident_expression -> finish_ident_expression = o#expression
+    method expression_desc : expression_desc -> expression_desc =
+      function
+      | Length (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#length_object _x_i1 in Length (_x, _x_i1)
+      | Char_of_int _x -> let _x = o#expression _x in Char_of_int _x
+      | Char_to_int _x -> let _x = o#expression _x in Char_to_int _x
+      | Is_null_or_undefined _x ->
+          let _x = o#expression _x in Is_null_or_undefined _x
+      | String_append (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in String_append (_x, _x_i1)
+      | Bool _x -> let _x = o#bool _x in Bool _x
+      | Typeof _x -> let _x = o#expression _x in Typeof _x
+      | Js_not _x -> let _x = o#expression _x in Js_not _x
+      | Seq (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in Seq (_x, _x_i1)
+      | Cond (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in
+          let _x_i2 = o#expression _x_i2 in Cond (_x, _x_i1, _x_i2)
+      | Bin (_x, _x_i1, _x_i2) ->
+          let _x = o#binop _x in
+          let _x_i1 = o#expression _x_i1 in
+          let _x_i2 = o#expression _x_i2 in Bin (_x, _x_i1, _x_i2)
+      | FlatCall (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in FlatCall (_x, _x_i1)
+      | Call (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#expression) _x_i1 in
+          let _x_i2 = o#unknown _x_i2 in Call (_x, _x_i1, _x_i2)
+      | String_index (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in String_index (_x, _x_i1)
+      | Array_index (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in Array_index (_x, _x_i1)
+      | Static_index (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#string _x_i1 in
+          let _x_i2 = o#option (fun o -> o#int32) _x_i2
+          in Static_index (_x, _x_i1, _x_i2)
+      | New (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 =
+            o#option
+              (fun o -> (** where we use a trick [== null ] *)
+                 (* js true/false*)
                  (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence 
      [typeof] is an operator     
   *)
@@ -175,11 +287,60 @@ class virtual map =
           All exported declarations have to be OCaml identifiers
        2. Javascript dot (need to be preserved/or using quote)
      *)
-                 (* TODO: option remove *)
-                 (* The first parameter by default is false, 
+                 o#list (fun o -> o#expression))
+              _x_i1
+          in New (_x, _x_i1)
+      | Var _x -> let _x = o#vident _x in Var _x
+      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
+          let _x = o#bool _x in
+          let _x_i1 = o#list (fun o -> o#ident) _x_i1 in
+          let _x_i2 = o#block _x_i2 in
+          let _x_i3 = o#unknown _x_i3 in Fun (_x, _x_i1, _x_i2, _x_i3)
+      | Str (_x, _x_i1) ->
+          let _x = o#bool _x in let _x_i1 = o#string _x_i1 in Str (_x, _x_i1)
+      | Unicode _x -> let _x = o#string _x in Unicode _x
+      | Raw_js_code _x -> let _x = o#unknown _x in Raw_js_code _x
+      | Array (_x, _x_i1) ->
+          let _x = o#list (fun o -> o#expression) _x in
+          let _x_i1 = o#mutable_flag _x_i1 in Array (_x, _x_i1)
+      | Optional_block (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#bool _x_i1 in Optional_block (_x, _x_i1)
+      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
+          let _x = o#list (fun o -> o#expression) _x in
+          let _x_i1 = o#mutable_flag _x_i1 in
+          let _x_i2 = o#expression _x_i2 in
+          let _x_i3 = o#tag_info _x_i3
+          in Caml_block (_x, _x_i1, _x_i2, _x_i3)
+      | Caml_block_tag _x -> let _x = o#expression _x in Caml_block_tag _x
+      | Number _x -> let _x = o#number _x in Number _x
+      | Object _x -> let _x = o#property_map _x in Object _x
+      | Undefined -> Undefined
+      | Null -> Null
+    method expression : expression -> expression =
+      fun { expression_desc = _x; comment = _x_i1 } ->
+        let _x = o#expression_desc _x in
+        let _x_i1 = o#option (fun o -> o#string) _x_i1
+        in { expression_desc = _x; comment = _x_i1; }
+    method exports : exports -> exports = o#unknown
+    method exception_ident : exception_ident -> exception_ident = o#ident
+    method deps_program : deps_program -> deps_program =
+      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
+        let _x = o#program _x in
+        let _x_i1 = o#required_modules _x_i1 in
+        let _x_i2 = o#option (fun o -> o#string) _x_i2
+        in { program = _x; modules = _x_i1; side_effect = _x_i2; }
+    method case_clause : case_clause -> case_clause =
+      fun { switch_body = _x; should_break = _x_i1; comment = _x_i2 } ->
+        let _x = o#block _x in
+        let _x_i1 = o#bool _x_i1 in
+        let _x_i2 = o#option (fun o -> o#string) _x_i2
+        in { switch_body = _x; should_break = _x_i1; comment = _x_i2; }
+    method block : block -> block = (* TODO: option remove *)
+      (* The first parameter by default is false, 
      it will be true when it's a method
   *)
-                 (* A string is UTF-8 encoded, the string may contain
+      (* A string is UTF-8 encoded, the string may contain
        escape sequences.
        The first argument is used to mark it is non-pure, please
        don't optimize it, since it does have side effec, 
@@ -187,13 +348,13 @@ class virtual map =
        which is better to leave it alone
        The last argument is passed from as `j` from `{j||j}`
      *)
-                 (* It is escaped string, print delimited by '"'*)
-                 (* literally raw JS code 
+      (* It is escaped string, print delimited by '"'*)
+      (* literally raw JS code 
   *) (* [true] means [identity] *)
-                 (* The third argument is [tag] , forth is [tag_info] *)
-                 (* | Caml_uninitialized_obj of expression * expression *)
-                 (* [tag] and [size] tailed  for [Obj.new_block] *)
-                 (* For setter, it still return the value of expression, 
+      (* The third argument is [tag] , forth is [tag_info] *)
+      (* | Caml_uninitialized_obj of expression * expression *)
+      (* [tag] and [size] tailed  for [Obj.new_block] *)
+      (* For setter, it still return the value of expression, 
      we can not use 
      {[
        type 'a access = Get | Set of 'a
@@ -202,20 +363,20 @@ class virtual map =
      [Caml_block_tag] can return [undefined], 
      you have to use [E.tag] in a safe way     
   *)
-                 (* | Caml_block_set_tag of expression * expression *)
-                 (* | Caml_block_set_length of expression * expression *)
-                 (* It will just fetch tag, to make it safe, when creating it, 
+      (* | Caml_block_set_tag of expression * expression *)
+      (* | Caml_block_set_length of expression * expression *)
+      (* It will just fetch tag, to make it safe, when creating it, 
      we need apply "|0", we don't do it in the 
      last step since "|0" can potentially be optimized
   *)
-                 (* pure*) (* pure *)
-                 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
+      (* pure*) (* pure *)
+      (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
    block can be nested, specified in ES3 
  *)
-                 (* Delay some units like [primitive] into JS layer ,
+      (* Delay some units like [primitive] into JS layer ,
    benefit: better cross module inlining, and smaller IR size?
  *)
-                 (* 
+      (* 
   [closure] captured loop mutable values in the outer loop
 
   check if it contains loop mutable values, happens in nested loop
@@ -241,7 +402,7 @@ class virtual map =
   contains a block side effect
   TODO: create such example
 *)
-                 (* Since in OCaml, 
+      (* Since in OCaml, 
    
   [for i = 0 to k end do done ]
   k is only evaluated once , to encode this invariant in JS IR,
@@ -250,7 +411,7 @@ class virtual map =
   TODO: currently we guarantee that [bound] was only 
   excecuted once, should encode this in AST level
 *)
-                 (* Can be simplified to keep the semantics of OCaml
+      (* Can be simplified to keep the semantics of OCaml
    For (var i, e, ...){
      let  j = ... 
    }
@@ -262,7 +423,7 @@ class virtual map =
      })(i)
    }
 *)
-                 (* Single return is good for ininling..
+      (* Single return is good for ininling..
    However, when you do tail-call optmization
    you loose the expression oriented semantics
    Block is useful for implementing goto
@@ -272,12 +433,12 @@ class virtual map =
    }
    ]}
 *)
-                 (* Function declaration and Variable declaration  *)
-                 (* check if it contains loop mutable values, happens in nested loop *)
-                 (* only used when inline a fucntion *)
-                 (* Here we need track back a bit ?, move Return to Function ...
+      (* Function declaration and Variable declaration  *)
+      (* check if it contains loop mutable values, happens in nested loop *)
+      (* only used when inline a fucntion *)
+      (* Here we need track back a bit ?, move Return to Function ...
                               Then we can only have one Return, which is not good *)
-                 (* since in ocaml, it's expression oriented langauge, [return] in
+      (* since in ocaml, it's expression oriented langauge, [return] in
     general has no jumps, it only happens when we do 
     tailcall conversion, in that case there is a jump.
     However, currently  a single [break] is good to cover
@@ -287,178 +448,7 @@ class virtual map =
     A more robust signature would be 
     {[ goto : label option ; ]}
   *)
-                 o#case_clause (fun o -> o#int))
-              _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in Int_switch (_x, _x_i1, _x_i2)
-      | String_switch (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 =
-            o#list (fun o -> o#case_clause (fun o -> o#string)) _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in String_switch (_x, _x_i1, _x_i2)
-      | Throw _x -> let _x = o#expression _x in Throw _x
-      | Try (_x, _x_i1, _x_i2) ->
-          let _x = o#block _x in
-          let _x_i1 =
-            o#option
-              (fun o (_x, _x_i1) ->
-                 let _x = o#exception_ident _x in
-                 let _x_i1 = o#block _x_i1 in (_x, _x_i1))
-              _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in Try (_x, _x_i1, _x_i2)
-      | Debugger -> Debugger
-    method statement : statement -> statement =
-      fun { statement_desc = _x; comment = _x_i1 } ->
-        let _x = o#statement_desc _x in
-        let _x_i1 = o#option (fun o -> o#string) _x_i1
-        in { statement_desc = _x; comment = _x_i1; }
-    method required_modules : required_modules -> required_modules =
-      o#list (fun o -> o#module_id)
-    method property_name : property_name -> property_name = o#unknown
-    method property_map : property_map -> property_map =
-      o#list
-        (fun o (_x, _x_i1) ->
-           let _x = o#property_name _x in
-           let _x_i1 = o#expression _x_i1 in (_x, _x_i1))
-    method property : property -> property = o#unknown
-    method program : program -> program =
-      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
-        let _x = o#block _x in
-        let _x_i1 = o#exports _x_i1 in
-        let _x_i2 = o#unknown _x_i2
-        in { block = _x; exports = _x_i1; export_set = _x_i2; }
-    method number : number -> number = o#unknown
-    method mutable_flag : mutable_flag -> mutable_flag = o#unknown
-    method module_id : module_id -> module_id =
-      fun { id = _x; kind = _x_i1 } ->
-        let _x = o#ident _x in
-        let _x_i1 = o#unknown _x_i1 in { id = _x; kind = _x_i1; }
-    method length_object : length_object -> length_object = o#unknown
-    method label : label -> label = o#string
-    method kind : kind -> kind = o#unknown
-    method jsint : jsint -> jsint = o#int32
-    method int_op : int_op -> int_op = o#unknown
-    method ident_info : ident_info -> ident_info = o#unknown
-    method ident : ident -> ident = o#unknown
-    method for_ident_expression :
-      for_ident_expression -> for_ident_expression = o#expression
-    method for_ident : for_ident -> for_ident = o#ident
-    method for_direction : for_direction -> for_direction = o#unknown
-    method finish_ident_expression :
-      finish_ident_expression -> finish_ident_expression = o#expression
-    method expression_desc : expression_desc -> expression_desc =
-      function
-      | Length (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#length_object _x_i1 in Length (_x, _x_i1)
-      | Char_of_int _x -> let _x = o#expression _x in Char_of_int _x
-      | Char_to_int _x -> let _x = o#expression _x in Char_to_int _x
-      | Is_null_or_undefined _x ->
-          let _x = o#expression _x in Is_null_or_undefined _x
-      | String_append (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in String_append (_x, _x_i1)
-      | Bool _x -> let _x = o#bool _x in Bool _x
-      | Typeof _x -> let _x = o#expression _x in Typeof _x
-      | Js_not _x -> let _x = o#expression _x in Js_not _x
-      | Seq (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in Seq (_x, _x_i1)
-      | Cond (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in
-          let _x_i2 = o#expression _x_i2 in Cond (_x, _x_i1, _x_i2)
-      | Bin (_x, _x_i1, _x_i2) ->
-          let _x = o#binop _x in
-          let _x_i1 = o#expression _x_i1 in
-          let _x_i2 = o#expression _x_i2 in Bin (_x, _x_i1, _x_i2)
-      | FlatCall (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in FlatCall (_x, _x_i1)
-      | Call (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#list (fun o -> o#expression) _x_i1 in
-          let _x_i2 = o#unknown _x_i2 in Call (_x, _x_i1, _x_i2)
-      | String_index (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in String_index (_x, _x_i1)
-      | Array_index (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in Array_index (_x, _x_i1)
-      | Static_index (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#string _x_i1 in
-          let _x_i2 = o#option (fun o -> o#int32) _x_i2
-          in Static_index (_x, _x_i1, _x_i2)
-      | New (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 =
-            o#option (fun o -> o#list (fun o -> o#expression)) _x_i1
-          in New (_x, _x_i1)
-      | Var _x -> let _x = o#vident _x in Var _x
-      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
-          let _x = o#bool _x in
-          let _x_i1 = o#list (fun o -> o#ident) _x_i1 in
-          let _x_i2 = o#block _x_i2 in
-          let _x_i3 = o#unknown _x_i3 in Fun (_x, _x_i1, _x_i2, _x_i3)
-      | Str (_x, _x_i1) ->
-          let _x = o#bool _x in let _x_i1 = o#string _x_i1 in Str (_x, _x_i1)
-      | Unicode _x -> let _x = o#string _x in Unicode _x
-      | Raw_js_code _x -> let _x = o#unknown _x in Raw_js_code _x
-      | Array (_x, _x_i1) ->
-          let _x = o#list (fun o -> o#expression) _x in
-          let _x_i1 = o#mutable_flag _x_i1 in Array (_x, _x_i1)
-      | Optional_block (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#bool _x_i1 in Optional_block (_x, _x_i1)
-      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
-          let _x = o#list (fun o -> o#expression) _x in
-          let _x_i1 = o#mutable_flag _x_i1 in
-          let _x_i2 = o#expression _x_i2 in
-          let _x_i3 = o#tag_info _x_i3
-          in Caml_block (_x, _x_i1, _x_i2, _x_i3)
-      | Caml_block_tag _x -> let _x = o#expression _x in Caml_block_tag _x
-      | Number _x -> let _x = o#number _x in Number _x
-      | Object _x -> let _x = o#property_map _x in Object _x
-      | Undefined -> Undefined
-      | Null -> Null
-    method expression : expression -> expression =
-      fun { expression_desc = _x; comment = _x_i1 } ->
-        let _x = o#expression_desc _x in
-        let _x_i1 = o#option (fun o -> o#string) _x_i1
-        in { expression_desc = _x; comment = _x_i1; }
-    method exports : exports -> exports = o#unknown
-    method exception_ident : exception_ident -> exception_ident = o#ident
-    method deps_program : deps_program -> deps_program =
-      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
-        let _x = o#program _x in
-        let _x_i1 = o#required_modules _x_i1 in
-        let _x_i2 = o#option (fun o -> o#string) _x_i2
-        in { program = _x; modules = _x_i1; side_effect = _x_i2; }
-    method case_clause :
-      'a 'a_out.
-        ('self_type -> 'a -> 'a_out) -> 'a case_clause -> 'a_out case_clause =
-      fun _f_a
-        {
-          switch_case = _x;
-          switch_body = _x_i1;
-          should_break = _x_i2;
-          comment = _x_i3
-        } ->
-        let _x = _f_a o _x in
-        let _x_i1 = o#block _x_i1 in
-        let _x_i2 = o#bool _x_i2 in
-        let _x_i3 = o#option (fun o -> o#string) _x_i3
-        in
-          {
-            switch_case = _x;
-            switch_body = _x_i1;
-            should_break = _x_i2;
-            comment = _x_i3;
-          }
-    method block : block -> block = (* true means break *)
+      (* true means break *)
       (* TODO: For efficency: block should not be a list, it should be able to 
    be concatenated in both ways 
  *)
diff --git a/jscomp/core/js_of_lam_variant.ml b/jscomp/core/js_of_lam_variant.ml
index a892c612c2..827085c8fc 100644
--- a/jscomp/core/js_of_lam_variant.ml
+++ b/jscomp/core/js_of_lam_variant.ml
@@ -43,7 +43,7 @@ let eval (arg : J.expression) (dispatches : (string * string) list ) : E.t =
       E.of_block
         [(S.string_switch arg
             (Ext_list.map dispatches (fun (i,r) ->
-                 {J.switch_case = i ;
+                 i, J.{
                   switch_body = [S.return_stmt (E.str r)];
                   should_break = false; (* FIXME: if true, still print break*)
                   comment = None;
@@ -71,7 +71,7 @@ let eval_as_event (arg : J.expression) (dispatches : (string * string) list opti
       
         (S.string_switch (E.poly_var_tag_access arg)
         (Ext_list.map dispatches (fun (i,r) ->
-              {J.switch_case = i ;
+              i, J.{
                switch_body = [S.return_stmt (E.str r)];
                should_break = false; (* FIXME: if true, still print break*)
                comment = None;
@@ -103,7 +103,7 @@ let eval_as_int (arg : J.expression) (dispatches : (string * int) list ) : E.t
     E.of_block
       [(S.string_switch arg
       (Ext_list.map dispatches (fun (i,r) ->
-              {J.switch_case = i ;
+              i, J.{
                switch_body = [S.return_stmt (E.int (Int32.of_int  r))];
                should_break = false; (* FIXME: if true, still print break*)
                comment = None;
diff --git a/jscomp/core/js_stmt_make.ml b/jscomp/core/js_stmt_make.ml
index a2c9c1d430..b2018d7189 100644
--- a/jscomp/core/js_stmt_make.ml
+++ b/jscomp/core/js_stmt_make.ml
@@ -98,13 +98,13 @@ let int_switch
     ?(declaration : (J.property * Ident.t) option )
     ?(default : J.block option)
     (e : J.expression)  
-    (clauses : int J.case_clause list): t = 
+    (clauses : (int * J.case_clause) list): t = 
   match e.expression_desc with 
   | Number (Int {i; _}) -> 
     let continuation =  
       match Ext_list.find_opt clauses
-              (fun x ->
-                 if x.switch_case = Int32.to_int i then
+              (fun (switch_case,x) ->
+                 if switch_case = Int32.to_int i then
                    Some x.switch_body else None ) 
       with 
       | Some case -> case 
@@ -137,12 +137,12 @@ let string_switch
   ?(declaration : (J.property * Ident.t) option) 
   ?(default : J.block option)
   (e : J.expression)  
-  (clauses : string J.case_clause list): t= 
+  (clauses : (string * J.case_clause) list): t= 
   match e.expression_desc with 
   | Str (_,s) -> 
     let continuation = 
-      match Ext_list.find_opt clauses (fun  x ->
-                 if x.switch_case = s then 
+      match Ext_list.find_opt clauses (fun  (switch_case, x) ->
+                 if switch_case = s then 
                    Some x.switch_body
                  else None  
               ) with 
diff --git a/jscomp/core/js_stmt_make.mli b/jscomp/core/js_stmt_make.mli
index b4ee71ec57..eed797598b 100644
--- a/jscomp/core/js_stmt_make.mli
+++ b/jscomp/core/js_stmt_make.mli
@@ -84,7 +84,7 @@ val int_switch :
   ?declaration:Lam_compat.let_kind * Ident.t -> 
   ?default:J.block -> 
   J.expression -> 
-  int J.case_clause list -> 
+  (int * J.case_clause) list -> 
   t 
 
 val string_switch : 
@@ -92,7 +92,7 @@ val string_switch :
   ?declaration:Lam_compat.let_kind * Ident.t -> 
   ?default:J.block ->
   J.expression -> 
-  string J.case_clause list ->
+  (string * J.case_clause) list ->
   t
 
 (** Just declaration without initialization *)  
diff --git a/jscomp/core/lam_compile.ml b/jscomp/core/lam_compile.ml
index 8ecdefb78c..46ab026c75 100644
--- a/jscomp/core/lam_compile.ml
+++ b/jscomp/core/lam_compile.ml
@@ -490,7 +490,7 @@ and compile_general_cases
   Lam_compile_context.t ->
   (?default:J.block ->
    ?declaration:Lam_compat.let_kind * Ident.t  ->
-   _ -> 'a J.case_clause list ->  J.statement) ->
+   _ -> ('a * J.case_clause) list ->  J.statement) ->
   _ ->
   ('a * Lam.t) list -> default_case -> J.block
   = fun
@@ -501,7 +501,7 @@ and compile_general_cases
   (switch :
   ?default:J.block ->
    ?declaration:Lam_compat.let_kind * Ident.t  ->
-   _ -> _ J.case_clause list ->  J.statement
+   _ -> (_ * J.case_clause) list ->  J.statement
    )
    (switch_exp : J.expression)
    (cases : (_ * Lam.t) list)
@@ -571,13 +571,13 @@ and compile_general_cases
                               should_break
                             else
                               should_break && Lam_exit_code.has_exit lam in
-                        {J.switch_case ;
+                          switch_case , J.{
                             switch_body;
                             should_break;
                             comment = make_comment switch_case;
                         }
                       else
-                        { switch_case; switch_body = []; should_break = false; comment = make_comment switch_case; }
+                      switch_case, {switch_body = []; should_break = false; comment = make_comment switch_case; }
                     )                   
               
               (* TODO: we should also group default *)
diff --git a/lib/4.06.1/unstable/js_compiler.ml b/lib/4.06.1/unstable/js_compiler.ml
index 90f910f0b6..6fa6af795e 100644
--- a/lib/4.06.1/unstable/js_compiler.ml
+++ b/lib/4.06.1/unstable/js_compiler.ml
@@ -86060,8 +86060,8 @@ and statement_desc =
     {[ goto : label option ; ]}
   *)
 
-  | Int_switch of expression * int case_clause list * block option 
-  | String_switch of expression * string case_clause list * block option 
+  | Int_switch of expression * int_clause list * block option 
+  | String_switch of expression * string_clause list * block option 
   | Throw of expression
   | Try of block * (exception_ident * block) option * block option
   | Debugger
@@ -86084,9 +86084,9 @@ and variable_declaration = {
   property : property;
   ident_info : ident_info;
 }
-
-and 'a case_clause = { 
-  switch_case : 'a ; 
+and string_clause = string * case_clause
+and int_clause =  int * case_clause
+and case_clause = {   
   switch_body : block ;
   should_break :  bool ;  (* true means break *)
   comment : string option ;
@@ -86557,6 +86557,9 @@ class virtual fold =
         let o = o#option (fun o -> o#expression) _x_i1 in
         let o = o#property _x_i2 in let o = o#ident_info _x_i3 in o
     method tag_info : tag_info -> 'self_type = o#unknown
+    method string_clause : string_clause -> 'self_type =
+      fun (_x, _x_i1) ->
+        let o = o#string _x in let o = o#case_clause _x_i1 in o
     method statement_desc : statement_desc -> 'self_type =
       function
       | Block _x -> let o = o#block _x in o
@@ -86580,10 +86583,28 @@ class virtual fold =
       | Return _x -> let o = o#expression _x in o
       | Int_switch (_x, _x_i1, _x_i2) ->
           let o = o#expression _x in
+          let o = o#list (fun o -> o#int_clause) _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | String_switch (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#list (fun o -> o#string_clause) _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | Throw _x -> let o = o#expression _x in o
+      | Try (_x, _x_i1, _x_i2) ->
+          let o = o#block _x in
           let o =
-            o#list
-              (fun o ->
-                 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+            o#option
+              (fun o (_x, _x_i1) ->
+                 let o = o#exception_ident _x in let o = o#block _x_i1 in o)
+              _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | Debugger -> o
+    method statement : statement -> 'self_type =
+      fun { statement_desc = _x; comment = _x_i1 } ->
+        let o = o#statement_desc _x in
+        let o = o#option (fun o -> o#string) _x_i1 in o
+    method required_modules : required_modules -> 'self_type =
+      (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
  * 
  * 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
@@ -86606,7 +86627,7 @@ class virtual fold =
  * 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. *)
-                 (* Javascript IR
+      (* Javascript IR
   
     It's a subset of Javascript AST specialized for OCaml lambda backend
 
@@ -86614,15 +86635,18 @@ class virtual fold =
     convention and [Block] is just a sequence of statements, which means it does 
     not introduce new scope
 *)
-                 (* TODO: it seems that camlp4of supports very limited structures
+      (* TODO: it seems that camlp4of supports very limited structures
    it does not even support attributes like `[@@@warning "-30"]
    we should get rid of such dependency ASAP
 *)
-                 (** object literal, if key is ident, in this case, it might be renamed by 
+      o#list (fun o -> o#module_id)
+    method property_name : property_name -> 'self_type = o#unknown
+    method property_map : property_map -> 'self_type =
+      (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-                 (* Since camldot is only available for toplevel module accessors,
+      (* Since camldot is only available for toplevel module accessors,
        we don't need print  `A.length$2`
        just print `A.length` - it's guarateed to be unique
        
@@ -86637,7 +86661,74 @@ class virtual fold =
          Qualified (_, Runtime, Some "caml_int_compare")         
        ]}       
      *)
-                 (** where we use a trick [== null ] *) (* js true/false*)
+      o#list
+        (fun o (_x, _x_i1) ->
+           let o = o#property_name _x in let o = o#expression _x_i1 in o)
+    method property : property -> 'self_type = o#unknown
+    method program : program -> 'self_type =
+      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
+        let o = o#block _x in
+        let o = o#exports _x_i1 in let o = o#unknown _x_i2 in o
+    method number : number -> 'self_type = o#unknown
+    method mutable_flag : mutable_flag -> 'self_type = o#unknown
+    method module_id : module_id -> 'self_type =
+      fun { id = _x; kind = _x_i1 } ->
+        let o = o#ident _x in let o = o#unknown _x_i1 in o
+    method length_object : length_object -> 'self_type = o#unknown
+    method label : label -> 'self_type = o#string
+    method kind : kind -> 'self_type = o#unknown
+    method jsint : jsint -> 'self_type = o#int32
+    method int_op : int_op -> 'self_type = o#unknown
+    method int_clause : int_clause -> 'self_type =
+      fun (_x, _x_i1) -> let o = o#int _x in let o = o#case_clause _x_i1 in o
+    method ident_info : ident_info -> 'self_type = o#unknown
+    method ident : ident -> 'self_type = o#unknown
+    method for_ident_expression : for_ident_expression -> 'self_type =
+      o#expression
+    method for_ident : for_ident -> 'self_type = o#ident
+    method for_direction : for_direction -> 'self_type = o#unknown
+    method finish_ident_expression : finish_ident_expression -> 'self_type =
+      o#expression
+    method expression_desc : expression_desc -> 'self_type =
+      function
+      | Length (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#length_object _x_i1 in o
+      | Char_of_int _x -> let o = o#expression _x in o
+      | Char_to_int _x -> let o = o#expression _x in o
+      | Is_null_or_undefined _x -> let o = o#expression _x in o
+      | String_append (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Bool _x -> let o = o#bool _x in o
+      | Typeof _x -> let o = o#expression _x in o
+      | Js_not _x -> let o = o#expression _x in o
+      | Seq (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Cond (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
+      | Bin (_x, _x_i1, _x_i2) ->
+          let o = o#binop _x in
+          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
+      | FlatCall (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Call (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#list (fun o -> o#expression) _x_i1 in
+          let o = o#unknown _x_i2 in o
+      | String_index (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Array_index (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Static_index (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#string _x_i1 in
+          let o = o#option (fun o -> o#int32) _x_i2 in o
+      | New (_x, _x_i1) ->
+          let o = o#expression _x in
+          let o =
+            o#option
+              (fun o -> (** where we use a trick [== null ] *)
+                 (* js true/false*)
                  (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence 
      [typeof] is an operator     
   *)
@@ -86672,11 +86763,52 @@ class virtual fold =
           All exported declarations have to be OCaml identifiers
        2. Javascript dot (need to be preserved/or using quote)
      *)
-                 (* TODO: option remove *)
-                 (* The first parameter by default is false, 
+                 o#list (fun o -> o#expression))
+              _x_i1
+          in o
+      | Var _x -> let o = o#vident _x in o
+      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
+          let o = o#bool _x in
+          let o = o#list (fun o -> o#ident) _x_i1 in
+          let o = o#block _x_i2 in let o = o#unknown _x_i3 in o
+      | Str (_x, _x_i1) -> let o = o#bool _x in let o = o#string _x_i1 in o
+      | Unicode _x -> let o = o#string _x in o
+      | Raw_js_code _x -> let o = o#unknown _x in o
+      | Array (_x, _x_i1) ->
+          let o = o#list (fun o -> o#expression) _x in
+          let o = o#mutable_flag _x_i1 in o
+      | Optional_block (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#bool _x_i1 in o
+      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
+          let o = o#list (fun o -> o#expression) _x in
+          let o = o#mutable_flag _x_i1 in
+          let o = o#expression _x_i2 in let o = o#tag_info _x_i3 in o
+      | Caml_block_tag _x -> let o = o#expression _x in o
+      | Number _x -> let o = o#number _x in o
+      | Object _x -> let o = o#property_map _x in o
+      | Undefined -> o
+      | Null -> o
+    method expression : expression -> 'self_type =
+      fun { expression_desc = _x; comment = _x_i1 } ->
+        let o = o#expression_desc _x in
+        let o = o#option (fun o -> o#string) _x_i1 in o
+    method exports : exports -> 'self_type = o#unknown
+    method exception_ident : exception_ident -> 'self_type = o#ident
+    method deps_program : deps_program -> 'self_type =
+      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
+        let o = o#program _x in
+        let o = o#required_modules _x_i1 in
+        let o = o#option (fun o -> o#string) _x_i2 in o
+    method case_clause : case_clause -> 'self_type =
+      fun { switch_body = _x; should_break = _x_i1; comment = _x_i2 } ->
+        let o = o#block _x in
+        let o = o#bool _x_i1 in
+        let o = o#option (fun o -> o#string) _x_i2 in o
+    method block : block -> 'self_type = (* TODO: option remove *)
+      (* The first parameter by default is false, 
      it will be true when it's a method
   *)
-                 (* A string is UTF-8 encoded, the string may contain
+      (* A string is UTF-8 encoded, the string may contain
        escape sequences.
        The first argument is used to mark it is non-pure, please
        don't optimize it, since it does have side effec, 
@@ -86684,13 +86816,13 @@ class virtual fold =
        which is better to leave it alone
        The last argument is passed from as `j` from `{j||j}`
      *)
-                 (* It is escaped string, print delimited by '"'*)
-                 (* literally raw JS code 
+      (* It is escaped string, print delimited by '"'*)
+      (* literally raw JS code 
   *) (* [true] means [identity] *)
-                 (* The third argument is [tag] , forth is [tag_info] *)
-                 (* | Caml_uninitialized_obj of expression * expression *)
-                 (* [tag] and [size] tailed  for [Obj.new_block] *)
-                 (* For setter, it still return the value of expression, 
+      (* The third argument is [tag] , forth is [tag_info] *)
+      (* | Caml_uninitialized_obj of expression * expression *)
+      (* [tag] and [size] tailed  for [Obj.new_block] *)
+      (* For setter, it still return the value of expression, 
      we can not use 
      {[
        type 'a access = Get | Set of 'a
@@ -86699,20 +86831,20 @@ class virtual fold =
      [Caml_block_tag] can return [undefined], 
      you have to use [E.tag] in a safe way     
   *)
-                 (* | Caml_block_set_tag of expression * expression *)
-                 (* | Caml_block_set_length of expression * expression *)
-                 (* It will just fetch tag, to make it safe, when creating it, 
+      (* | Caml_block_set_tag of expression * expression *)
+      (* | Caml_block_set_length of expression * expression *)
+      (* It will just fetch tag, to make it safe, when creating it, 
      we need apply "|0", we don't do it in the 
      last step since "|0" can potentially be optimized
   *)
-                 (* pure*) (* pure *)
-                 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
+      (* pure*) (* pure *)
+      (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
    block can be nested, specified in ES3 
  *)
-                 (* Delay some units like [primitive] into JS layer ,
+      (* Delay some units like [primitive] into JS layer ,
    benefit: better cross module inlining, and smaller IR size?
  *)
-                 (* 
+      (* 
   [closure] captured loop mutable values in the outer loop
 
   check if it contains loop mutable values, happens in nested loop
@@ -86738,7 +86870,7 @@ class virtual fold =
   contains a block side effect
   TODO: create such example
 *)
-                 (* Since in OCaml, 
+      (* Since in OCaml, 
    
   [for i = 0 to k end do done ]
   k is only evaluated once , to encode this invariant in JS IR,
@@ -86747,7 +86879,7 @@ class virtual fold =
   TODO: currently we guarantee that [bound] was only 
   excecuted once, should encode this in AST level
 *)
-                 (* Can be simplified to keep the semantics of OCaml
+      (* Can be simplified to keep the semantics of OCaml
    For (var i, e, ...){
      let  j = ... 
    }
@@ -86759,7 +86891,7 @@ class virtual fold =
      })(i)
    }
 *)
-                 (* Single return is good for ininling..
+      (* Single return is good for ininling..
    However, when you do tail-call optmization
    you loose the expression oriented semantics
    Block is useful for implementing goto
@@ -86769,12 +86901,12 @@ class virtual fold =
    }
    ]}
 *)
-                 (* Function declaration and Variable declaration  *)
-                 (* check if it contains loop mutable values, happens in nested loop *)
-                 (* only used when inline a fucntion *)
-                 (* Here we need track back a bit ?, move Return to Function ...
+      (* Function declaration and Variable declaration  *)
+      (* check if it contains loop mutable values, happens in nested loop *)
+      (* only used when inline a fucntion *)
+      (* Here we need track back a bit ?, move Return to Function ...
                               Then we can only have one Return, which is not good *)
-                 (* since in ocaml, it's expression oriented langauge, [return] in
+      (* since in ocaml, it's expression oriented langauge, [return] in
     general has no jumps, it only happens when we do 
     tailcall conversion, in that case there is a jump.
     However, currently  a single [break] is good to cover
@@ -86784,143 +86916,7 @@ class virtual fold =
     A more robust signature would be 
     {[ goto : label option ; ]}
   *)
-                 o#case_clause (fun o -> o#int))
-              _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | String_switch (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o =
-            o#list (fun o -> o#case_clause (fun o -> o#string)) _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | Throw _x -> let o = o#expression _x in o
-      | Try (_x, _x_i1, _x_i2) ->
-          let o = o#block _x in
-          let o =
-            o#option
-              (fun o (_x, _x_i1) ->
-                 let o = o#exception_ident _x in let o = o#block _x_i1 in o)
-              _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | Debugger -> o
-    method statement : statement -> 'self_type =
-      fun { statement_desc = _x; comment = _x_i1 } ->
-        let o = o#statement_desc _x in
-        let o = o#option (fun o -> o#string) _x_i1 in o
-    method required_modules : required_modules -> 'self_type =
-      o#list (fun o -> o#module_id)
-    method property_name : property_name -> 'self_type = o#unknown
-    method property_map : property_map -> 'self_type =
-      o#list
-        (fun o (_x, _x_i1) ->
-           let o = o#property_name _x in let o = o#expression _x_i1 in o)
-    method property : property -> 'self_type = o#unknown
-    method program : program -> 'self_type =
-      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
-        let o = o#block _x in
-        let o = o#exports _x_i1 in let o = o#unknown _x_i2 in o
-    method number : number -> 'self_type = o#unknown
-    method mutable_flag : mutable_flag -> 'self_type = o#unknown
-    method module_id : module_id -> 'self_type =
-      fun { id = _x; kind = _x_i1 } ->
-        let o = o#ident _x in let o = o#unknown _x_i1 in o
-    method length_object : length_object -> 'self_type = o#unknown
-    method label : label -> 'self_type = o#string
-    method kind : kind -> 'self_type = o#unknown
-    method jsint : jsint -> 'self_type = o#int32
-    method int_op : int_op -> 'self_type = o#unknown
-    method ident_info : ident_info -> 'self_type = o#unknown
-    method ident : ident -> 'self_type = o#unknown
-    method for_ident_expression : for_ident_expression -> 'self_type =
-      o#expression
-    method for_ident : for_ident -> 'self_type = o#ident
-    method for_direction : for_direction -> 'self_type = o#unknown
-    method finish_ident_expression : finish_ident_expression -> 'self_type =
-      o#expression
-    method expression_desc : expression_desc -> 'self_type =
-      function
-      | Length (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#length_object _x_i1 in o
-      | Char_of_int _x -> let o = o#expression _x in o
-      | Char_to_int _x -> let o = o#expression _x in o
-      | Is_null_or_undefined _x -> let o = o#expression _x in o
-      | String_append (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Bool _x -> let o = o#bool _x in o
-      | Typeof _x -> let o = o#expression _x in o
-      | Js_not _x -> let o = o#expression _x in o
-      | Seq (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Cond (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
-      | Bin (_x, _x_i1, _x_i2) ->
-          let o = o#binop _x in
-          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
-      | FlatCall (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Call (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#list (fun o -> o#expression) _x_i1 in
-          let o = o#unknown _x_i2 in o
-      | String_index (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Array_index (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Static_index (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#string _x_i1 in
-          let o = o#option (fun o -> o#int32) _x_i2 in o
-      | New (_x, _x_i1) ->
-          let o = o#expression _x in
-          let o = o#option (fun o -> o#list (fun o -> o#expression)) _x_i1
-          in o
-      | Var _x -> let o = o#vident _x in o
-      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
-          let o = o#bool _x in
-          let o = o#list (fun o -> o#ident) _x_i1 in
-          let o = o#block _x_i2 in let o = o#unknown _x_i3 in o
-      | Str (_x, _x_i1) -> let o = o#bool _x in let o = o#string _x_i1 in o
-      | Unicode _x -> let o = o#string _x in o
-      | Raw_js_code _x -> let o = o#unknown _x in o
-      | Array (_x, _x_i1) ->
-          let o = o#list (fun o -> o#expression) _x in
-          let o = o#mutable_flag _x_i1 in o
-      | Optional_block (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#bool _x_i1 in o
-      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
-          let o = o#list (fun o -> o#expression) _x in
-          let o = o#mutable_flag _x_i1 in
-          let o = o#expression _x_i2 in let o = o#tag_info _x_i3 in o
-      | Caml_block_tag _x -> let o = o#expression _x in o
-      | Number _x -> let o = o#number _x in o
-      | Object _x -> let o = o#property_map _x in o
-      | Undefined -> o
-      | Null -> o
-    method expression : expression -> 'self_type =
-      fun { expression_desc = _x; comment = _x_i1 } ->
-        let o = o#expression_desc _x in
-        let o = o#option (fun o -> o#string) _x_i1 in o
-    method exports : exports -> 'self_type = o#unknown
-    method exception_ident : exception_ident -> 'self_type = o#ident
-    method deps_program : deps_program -> 'self_type =
-      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
-        let o = o#program _x in
-        let o = o#required_modules _x_i1 in
-        let o = o#option (fun o -> o#string) _x_i2 in o
-    method case_clause :
-      'a. ('self_type -> 'a -> 'self_type) -> 'a case_clause -> 'self_type =
-      fun _f_a
-        {
-          switch_case = _x;
-          switch_body = _x_i1;
-          should_break = _x_i2;
-          comment = _x_i3
-        } ->
-        let o = _f_a o _x in
-        let o = o#block _x_i1 in
-        let o = o#bool _x_i2 in
-        let o = o#option (fun o -> o#string) _x_i3 in o
-    method block : block -> 'self_type = (* true means break *)
+      (* true means break *)
       (* TODO: For efficency: block should not be a list, it should be able to 
    be concatenated in both ways 
  *)
@@ -90313,9 +90309,9 @@ and  pp_function ~is_method
     since it can be either [int] or [string]
 *)
 and pp_one_case_clause : 'a .
-  _ -> P.t -> (P.t -> 'a -> unit) -> 'a J.case_clause -> _
+  _ -> P.t -> (P.t -> 'a -> unit) -> ('a * J.case_clause) -> _
   = fun cxt f  pp_cond
-    ({switch_case; switch_body ; should_break; comment; } : _ J.case_clause) ->
+    (switch_case, ({switch_body ; should_break; comment; } :  J.case_clause)) ->
     let cxt =
       P.group f 1  (fun _ ->
           P.group f 1 (fun _ ->
@@ -90345,7 +90341,7 @@ and pp_one_case_clause : 'a .
     cxt
 
 and loop_case_clauses  :  'a . cxt ->
-  P.t -> (P.t -> 'a -> unit) -> 'a J.case_clause list -> cxt
+  P.t -> (P.t -> 'a -> unit) -> ('a * J.case_clause) list -> cxt
   = fun  cxt  f pp_cond cases ->
     Ext_list.fold_left cases cxt (fun acc x -> pp_one_case_clause acc f pp_cond x)              
 
@@ -99589,7 +99585,7 @@ val int_switch :
   ?declaration:Lam_compat.let_kind * Ident.t -> 
   ?default:J.block -> 
   J.expression -> 
-  int J.case_clause list -> 
+  (int * J.case_clause) list -> 
   t 
 
 val string_switch : 
@@ -99597,7 +99593,7 @@ val string_switch :
   ?declaration:Lam_compat.let_kind * Ident.t -> 
   ?default:J.block ->
   J.expression -> 
-  string J.case_clause list ->
+  (string * J.case_clause) list ->
   t
 
 (** Just declaration without initialization *)  
@@ -99807,13 +99803,13 @@ let int_switch
     ?(declaration : (J.property * Ident.t) option )
     ?(default : J.block option)
     (e : J.expression)  
-    (clauses : int J.case_clause list): t = 
+    (clauses : (int * J.case_clause) list): t = 
   match e.expression_desc with 
   | Number (Int {i; _}) -> 
     let continuation =  
       match Ext_list.find_opt clauses
-              (fun x ->
-                 if x.switch_case = Int32.to_int i then
+              (fun (switch_case,x) ->
+                 if switch_case = Int32.to_int i then
                    Some x.switch_body else None ) 
       with 
       | Some case -> case 
@@ -99846,12 +99842,12 @@ let string_switch
   ?(declaration : (J.property * Ident.t) option) 
   ?(default : J.block option)
   (e : J.expression)  
-  (clauses : string J.case_clause list): t= 
+  (clauses : (string * J.case_clause) list): t= 
   match e.expression_desc with 
   | Str (_,s) -> 
     let continuation = 
-      match Ext_list.find_opt clauses (fun  x ->
-                 if x.switch_case = s then 
+      match Ext_list.find_opt clauses (fun  (switch_case, x) ->
+                 if switch_case = s then 
                    Some x.switch_body
                  else None  
               ) with 
@@ -101742,6 +101738,10 @@ class virtual map =
           { ident = _x; value = _x_i1; property = _x_i2; ident_info = _x_i3;
           }
     method tag_info : tag_info -> tag_info = o#unknown
+    method string_clause : string_clause -> string_clause =
+      fun (_x, _x_i1) ->
+        let _x = o#string _x in
+        let _x_i1 = o#case_clause _x_i1 in (_x, _x_i1)
     method statement_desc : statement_desc -> statement_desc =
       function
       | Block _x -> let _x = o#block _x in Block _x
@@ -101769,13 +101769,36 @@ class virtual map =
       | Return _x -> let _x = o#expression _x in Return _x
       | Int_switch (_x, _x_i1, _x_i2) ->
           let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#int_clause) _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in Int_switch (_x, _x_i1, _x_i2)
+      | String_switch (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#string_clause) _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in String_switch (_x, _x_i1, _x_i2)
+      | Throw _x -> let _x = o#expression _x in Throw _x
+      | Try (_x, _x_i1, _x_i2) ->
+          let _x = o#block _x in
           let _x_i1 =
-            o#list
-              (fun o ->
-                 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
- * 
- * 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
+            o#option
+              (fun o (_x, _x_i1) ->
+                 let _x = o#exception_ident _x in
+                 let _x_i1 = o#block _x_i1 in (_x, _x_i1))
+              _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in Try (_x, _x_i1, _x_i2)
+      | Debugger -> Debugger
+    method statement : statement -> statement =
+      fun { statement_desc = _x; comment = _x_i1 } ->
+        let _x = o#statement_desc _x in
+        let _x_i1 = o#option (fun o -> o#string) _x_i1
+        in { statement_desc = _x; comment = _x_i1; }
+    method required_modules : required_modules -> required_modules =
+      (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * 
+ * 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.
  *
@@ -101795,7 +101818,7 @@ class virtual map =
  * 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. *)
-                 (* Javascript IR
+      (* Javascript IR
   
     It's a subset of Javascript AST specialized for OCaml lambda backend
 
@@ -101803,15 +101826,18 @@ class virtual map =
     convention and [Block] is just a sequence of statements, which means it does 
     not introduce new scope
 *)
-                 (* TODO: it seems that camlp4of supports very limited structures
+      (* TODO: it seems that camlp4of supports very limited structures
    it does not even support attributes like `[@@@warning "-30"]
    we should get rid of such dependency ASAP
 *)
-                 (** object literal, if key is ident, in this case, it might be renamed by 
+      o#list (fun o -> o#module_id)
+    method property_name : property_name -> property_name = o#unknown
+    method property_map : property_map -> property_map =
+      (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-                 (* Since camldot is only available for toplevel module accessors,
+      (* Since camldot is only available for toplevel module accessors,
        we don't need print  `A.length$2`
        just print `A.length` - it's guarateed to be unique
        
@@ -101826,7 +101852,89 @@ class virtual map =
          Qualified (_, Runtime, Some "caml_int_compare")         
        ]}       
      *)
-                 (** where we use a trick [== null ] *) (* js true/false*)
+      o#list
+        (fun o (_x, _x_i1) ->
+           let _x = o#property_name _x in
+           let _x_i1 = o#expression _x_i1 in (_x, _x_i1))
+    method property : property -> property = o#unknown
+    method program : program -> program =
+      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
+        let _x = o#block _x in
+        let _x_i1 = o#exports _x_i1 in
+        let _x_i2 = o#unknown _x_i2
+        in { block = _x; exports = _x_i1; export_set = _x_i2; }
+    method number : number -> number = o#unknown
+    method mutable_flag : mutable_flag -> mutable_flag = o#unknown
+    method module_id : module_id -> module_id =
+      fun { id = _x; kind = _x_i1 } ->
+        let _x = o#ident _x in
+        let _x_i1 = o#unknown _x_i1 in { id = _x; kind = _x_i1; }
+    method length_object : length_object -> length_object = o#unknown
+    method label : label -> label = o#string
+    method kind : kind -> kind = o#unknown
+    method jsint : jsint -> jsint = o#int32
+    method int_op : int_op -> int_op = o#unknown
+    method int_clause : int_clause -> int_clause =
+      fun (_x, _x_i1) ->
+        let _x = o#int _x in let _x_i1 = o#case_clause _x_i1 in (_x, _x_i1)
+    method ident_info : ident_info -> ident_info = o#unknown
+    method ident : ident -> ident = o#unknown
+    method for_ident_expression :
+      for_ident_expression -> for_ident_expression = o#expression
+    method for_ident : for_ident -> for_ident = o#ident
+    method for_direction : for_direction -> for_direction = o#unknown
+    method finish_ident_expression :
+      finish_ident_expression -> finish_ident_expression = o#expression
+    method expression_desc : expression_desc -> expression_desc =
+      function
+      | Length (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#length_object _x_i1 in Length (_x, _x_i1)
+      | Char_of_int _x -> let _x = o#expression _x in Char_of_int _x
+      | Char_to_int _x -> let _x = o#expression _x in Char_to_int _x
+      | Is_null_or_undefined _x ->
+          let _x = o#expression _x in Is_null_or_undefined _x
+      | String_append (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in String_append (_x, _x_i1)
+      | Bool _x -> let _x = o#bool _x in Bool _x
+      | Typeof _x -> let _x = o#expression _x in Typeof _x
+      | Js_not _x -> let _x = o#expression _x in Js_not _x
+      | Seq (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in Seq (_x, _x_i1)
+      | Cond (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in
+          let _x_i2 = o#expression _x_i2 in Cond (_x, _x_i1, _x_i2)
+      | Bin (_x, _x_i1, _x_i2) ->
+          let _x = o#binop _x in
+          let _x_i1 = o#expression _x_i1 in
+          let _x_i2 = o#expression _x_i2 in Bin (_x, _x_i1, _x_i2)
+      | FlatCall (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in FlatCall (_x, _x_i1)
+      | Call (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#expression) _x_i1 in
+          let _x_i2 = o#unknown _x_i2 in Call (_x, _x_i1, _x_i2)
+      | String_index (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in String_index (_x, _x_i1)
+      | Array_index (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in Array_index (_x, _x_i1)
+      | Static_index (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#string _x_i1 in
+          let _x_i2 = o#option (fun o -> o#int32) _x_i2
+          in Static_index (_x, _x_i1, _x_i2)
+      | New (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 =
+            o#option
+              (fun o -> (** where we use a trick [== null ] *)
+                 (* js true/false*)
                  (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence 
      [typeof] is an operator     
   *)
@@ -101861,11 +101969,60 @@ class virtual map =
           All exported declarations have to be OCaml identifiers
        2. Javascript dot (need to be preserved/or using quote)
      *)
-                 (* TODO: option remove *)
-                 (* The first parameter by default is false, 
+                 o#list (fun o -> o#expression))
+              _x_i1
+          in New (_x, _x_i1)
+      | Var _x -> let _x = o#vident _x in Var _x
+      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
+          let _x = o#bool _x in
+          let _x_i1 = o#list (fun o -> o#ident) _x_i1 in
+          let _x_i2 = o#block _x_i2 in
+          let _x_i3 = o#unknown _x_i3 in Fun (_x, _x_i1, _x_i2, _x_i3)
+      | Str (_x, _x_i1) ->
+          let _x = o#bool _x in let _x_i1 = o#string _x_i1 in Str (_x, _x_i1)
+      | Unicode _x -> let _x = o#string _x in Unicode _x
+      | Raw_js_code _x -> let _x = o#unknown _x in Raw_js_code _x
+      | Array (_x, _x_i1) ->
+          let _x = o#list (fun o -> o#expression) _x in
+          let _x_i1 = o#mutable_flag _x_i1 in Array (_x, _x_i1)
+      | Optional_block (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#bool _x_i1 in Optional_block (_x, _x_i1)
+      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
+          let _x = o#list (fun o -> o#expression) _x in
+          let _x_i1 = o#mutable_flag _x_i1 in
+          let _x_i2 = o#expression _x_i2 in
+          let _x_i3 = o#tag_info _x_i3
+          in Caml_block (_x, _x_i1, _x_i2, _x_i3)
+      | Caml_block_tag _x -> let _x = o#expression _x in Caml_block_tag _x
+      | Number _x -> let _x = o#number _x in Number _x
+      | Object _x -> let _x = o#property_map _x in Object _x
+      | Undefined -> Undefined
+      | Null -> Null
+    method expression : expression -> expression =
+      fun { expression_desc = _x; comment = _x_i1 } ->
+        let _x = o#expression_desc _x in
+        let _x_i1 = o#option (fun o -> o#string) _x_i1
+        in { expression_desc = _x; comment = _x_i1; }
+    method exports : exports -> exports = o#unknown
+    method exception_ident : exception_ident -> exception_ident = o#ident
+    method deps_program : deps_program -> deps_program =
+      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
+        let _x = o#program _x in
+        let _x_i1 = o#required_modules _x_i1 in
+        let _x_i2 = o#option (fun o -> o#string) _x_i2
+        in { program = _x; modules = _x_i1; side_effect = _x_i2; }
+    method case_clause : case_clause -> case_clause =
+      fun { switch_body = _x; should_break = _x_i1; comment = _x_i2 } ->
+        let _x = o#block _x in
+        let _x_i1 = o#bool _x_i1 in
+        let _x_i2 = o#option (fun o -> o#string) _x_i2
+        in { switch_body = _x; should_break = _x_i1; comment = _x_i2; }
+    method block : block -> block = (* TODO: option remove *)
+      (* The first parameter by default is false, 
      it will be true when it's a method
   *)
-                 (* A string is UTF-8 encoded, the string may contain
+      (* A string is UTF-8 encoded, the string may contain
        escape sequences.
        The first argument is used to mark it is non-pure, please
        don't optimize it, since it does have side effec, 
@@ -101873,13 +102030,13 @@ class virtual map =
        which is better to leave it alone
        The last argument is passed from as `j` from `{j||j}`
      *)
-                 (* It is escaped string, print delimited by '"'*)
-                 (* literally raw JS code 
+      (* It is escaped string, print delimited by '"'*)
+      (* literally raw JS code 
   *) (* [true] means [identity] *)
-                 (* The third argument is [tag] , forth is [tag_info] *)
-                 (* | Caml_uninitialized_obj of expression * expression *)
-                 (* [tag] and [size] tailed  for [Obj.new_block] *)
-                 (* For setter, it still return the value of expression, 
+      (* The third argument is [tag] , forth is [tag_info] *)
+      (* | Caml_uninitialized_obj of expression * expression *)
+      (* [tag] and [size] tailed  for [Obj.new_block] *)
+      (* For setter, it still return the value of expression, 
      we can not use 
      {[
        type 'a access = Get | Set of 'a
@@ -101888,20 +102045,20 @@ class virtual map =
      [Caml_block_tag] can return [undefined], 
      you have to use [E.tag] in a safe way     
   *)
-                 (* | Caml_block_set_tag of expression * expression *)
-                 (* | Caml_block_set_length of expression * expression *)
-                 (* It will just fetch tag, to make it safe, when creating it, 
+      (* | Caml_block_set_tag of expression * expression *)
+      (* | Caml_block_set_length of expression * expression *)
+      (* It will just fetch tag, to make it safe, when creating it, 
      we need apply "|0", we don't do it in the 
      last step since "|0" can potentially be optimized
   *)
-                 (* pure*) (* pure *)
-                 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
+      (* pure*) (* pure *)
+      (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
    block can be nested, specified in ES3 
  *)
-                 (* Delay some units like [primitive] into JS layer ,
+      (* Delay some units like [primitive] into JS layer ,
    benefit: better cross module inlining, and smaller IR size?
  *)
-                 (* 
+      (* 
   [closure] captured loop mutable values in the outer loop
 
   check if it contains loop mutable values, happens in nested loop
@@ -101927,7 +102084,7 @@ class virtual map =
   contains a block side effect
   TODO: create such example
 *)
-                 (* Since in OCaml, 
+      (* Since in OCaml, 
    
   [for i = 0 to k end do done ]
   k is only evaluated once , to encode this invariant in JS IR,
@@ -101936,7 +102093,7 @@ class virtual map =
   TODO: currently we guarantee that [bound] was only 
   excecuted once, should encode this in AST level
 *)
-                 (* Can be simplified to keep the semantics of OCaml
+      (* Can be simplified to keep the semantics of OCaml
    For (var i, e, ...){
      let  j = ... 
    }
@@ -101948,7 +102105,7 @@ class virtual map =
      })(i)
    }
 *)
-                 (* Single return is good for ininling..
+      (* Single return is good for ininling..
    However, when you do tail-call optmization
    you loose the expression oriented semantics
    Block is useful for implementing goto
@@ -101958,12 +102115,12 @@ class virtual map =
    }
    ]}
 *)
-                 (* Function declaration and Variable declaration  *)
-                 (* check if it contains loop mutable values, happens in nested loop *)
-                 (* only used when inline a fucntion *)
-                 (* Here we need track back a bit ?, move Return to Function ...
+      (* Function declaration and Variable declaration  *)
+      (* check if it contains loop mutable values, happens in nested loop *)
+      (* only used when inline a fucntion *)
+      (* Here we need track back a bit ?, move Return to Function ...
                               Then we can only have one Return, which is not good *)
-                 (* since in ocaml, it's expression oriented langauge, [return] in
+      (* since in ocaml, it's expression oriented langauge, [return] in
     general has no jumps, it only happens when we do 
     tailcall conversion, in that case there is a jump.
     However, currently  a single [break] is good to cover
@@ -101973,178 +102130,7 @@ class virtual map =
     A more robust signature would be 
     {[ goto : label option ; ]}
   *)
-                 o#case_clause (fun o -> o#int))
-              _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in Int_switch (_x, _x_i1, _x_i2)
-      | String_switch (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 =
-            o#list (fun o -> o#case_clause (fun o -> o#string)) _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in String_switch (_x, _x_i1, _x_i2)
-      | Throw _x -> let _x = o#expression _x in Throw _x
-      | Try (_x, _x_i1, _x_i2) ->
-          let _x = o#block _x in
-          let _x_i1 =
-            o#option
-              (fun o (_x, _x_i1) ->
-                 let _x = o#exception_ident _x in
-                 let _x_i1 = o#block _x_i1 in (_x, _x_i1))
-              _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in Try (_x, _x_i1, _x_i2)
-      | Debugger -> Debugger
-    method statement : statement -> statement =
-      fun { statement_desc = _x; comment = _x_i1 } ->
-        let _x = o#statement_desc _x in
-        let _x_i1 = o#option (fun o -> o#string) _x_i1
-        in { statement_desc = _x; comment = _x_i1; }
-    method required_modules : required_modules -> required_modules =
-      o#list (fun o -> o#module_id)
-    method property_name : property_name -> property_name = o#unknown
-    method property_map : property_map -> property_map =
-      o#list
-        (fun o (_x, _x_i1) ->
-           let _x = o#property_name _x in
-           let _x_i1 = o#expression _x_i1 in (_x, _x_i1))
-    method property : property -> property = o#unknown
-    method program : program -> program =
-      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
-        let _x = o#block _x in
-        let _x_i1 = o#exports _x_i1 in
-        let _x_i2 = o#unknown _x_i2
-        in { block = _x; exports = _x_i1; export_set = _x_i2; }
-    method number : number -> number = o#unknown
-    method mutable_flag : mutable_flag -> mutable_flag = o#unknown
-    method module_id : module_id -> module_id =
-      fun { id = _x; kind = _x_i1 } ->
-        let _x = o#ident _x in
-        let _x_i1 = o#unknown _x_i1 in { id = _x; kind = _x_i1; }
-    method length_object : length_object -> length_object = o#unknown
-    method label : label -> label = o#string
-    method kind : kind -> kind = o#unknown
-    method jsint : jsint -> jsint = o#int32
-    method int_op : int_op -> int_op = o#unknown
-    method ident_info : ident_info -> ident_info = o#unknown
-    method ident : ident -> ident = o#unknown
-    method for_ident_expression :
-      for_ident_expression -> for_ident_expression = o#expression
-    method for_ident : for_ident -> for_ident = o#ident
-    method for_direction : for_direction -> for_direction = o#unknown
-    method finish_ident_expression :
-      finish_ident_expression -> finish_ident_expression = o#expression
-    method expression_desc : expression_desc -> expression_desc =
-      function
-      | Length (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#length_object _x_i1 in Length (_x, _x_i1)
-      | Char_of_int _x -> let _x = o#expression _x in Char_of_int _x
-      | Char_to_int _x -> let _x = o#expression _x in Char_to_int _x
-      | Is_null_or_undefined _x ->
-          let _x = o#expression _x in Is_null_or_undefined _x
-      | String_append (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in String_append (_x, _x_i1)
-      | Bool _x -> let _x = o#bool _x in Bool _x
-      | Typeof _x -> let _x = o#expression _x in Typeof _x
-      | Js_not _x -> let _x = o#expression _x in Js_not _x
-      | Seq (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in Seq (_x, _x_i1)
-      | Cond (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in
-          let _x_i2 = o#expression _x_i2 in Cond (_x, _x_i1, _x_i2)
-      | Bin (_x, _x_i1, _x_i2) ->
-          let _x = o#binop _x in
-          let _x_i1 = o#expression _x_i1 in
-          let _x_i2 = o#expression _x_i2 in Bin (_x, _x_i1, _x_i2)
-      | FlatCall (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in FlatCall (_x, _x_i1)
-      | Call (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#list (fun o -> o#expression) _x_i1 in
-          let _x_i2 = o#unknown _x_i2 in Call (_x, _x_i1, _x_i2)
-      | String_index (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in String_index (_x, _x_i1)
-      | Array_index (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in Array_index (_x, _x_i1)
-      | Static_index (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#string _x_i1 in
-          let _x_i2 = o#option (fun o -> o#int32) _x_i2
-          in Static_index (_x, _x_i1, _x_i2)
-      | New (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 =
-            o#option (fun o -> o#list (fun o -> o#expression)) _x_i1
-          in New (_x, _x_i1)
-      | Var _x -> let _x = o#vident _x in Var _x
-      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
-          let _x = o#bool _x in
-          let _x_i1 = o#list (fun o -> o#ident) _x_i1 in
-          let _x_i2 = o#block _x_i2 in
-          let _x_i3 = o#unknown _x_i3 in Fun (_x, _x_i1, _x_i2, _x_i3)
-      | Str (_x, _x_i1) ->
-          let _x = o#bool _x in let _x_i1 = o#string _x_i1 in Str (_x, _x_i1)
-      | Unicode _x -> let _x = o#string _x in Unicode _x
-      | Raw_js_code _x -> let _x = o#unknown _x in Raw_js_code _x
-      | Array (_x, _x_i1) ->
-          let _x = o#list (fun o -> o#expression) _x in
-          let _x_i1 = o#mutable_flag _x_i1 in Array (_x, _x_i1)
-      | Optional_block (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#bool _x_i1 in Optional_block (_x, _x_i1)
-      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
-          let _x = o#list (fun o -> o#expression) _x in
-          let _x_i1 = o#mutable_flag _x_i1 in
-          let _x_i2 = o#expression _x_i2 in
-          let _x_i3 = o#tag_info _x_i3
-          in Caml_block (_x, _x_i1, _x_i2, _x_i3)
-      | Caml_block_tag _x -> let _x = o#expression _x in Caml_block_tag _x
-      | Number _x -> let _x = o#number _x in Number _x
-      | Object _x -> let _x = o#property_map _x in Object _x
-      | Undefined -> Undefined
-      | Null -> Null
-    method expression : expression -> expression =
-      fun { expression_desc = _x; comment = _x_i1 } ->
-        let _x = o#expression_desc _x in
-        let _x_i1 = o#option (fun o -> o#string) _x_i1
-        in { expression_desc = _x; comment = _x_i1; }
-    method exports : exports -> exports = o#unknown
-    method exception_ident : exception_ident -> exception_ident = o#ident
-    method deps_program : deps_program -> deps_program =
-      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
-        let _x = o#program _x in
-        let _x_i1 = o#required_modules _x_i1 in
-        let _x_i2 = o#option (fun o -> o#string) _x_i2
-        in { program = _x; modules = _x_i1; side_effect = _x_i2; }
-    method case_clause :
-      'a 'a_out.
-        ('self_type -> 'a -> 'a_out) -> 'a case_clause -> 'a_out case_clause =
-      fun _f_a
-        {
-          switch_case = _x;
-          switch_body = _x_i1;
-          should_break = _x_i2;
-          comment = _x_i3
-        } ->
-        let _x = _f_a o _x in
-        let _x_i1 = o#block _x_i1 in
-        let _x_i2 = o#bool _x_i2 in
-        let _x_i3 = o#option (fun o -> o#string) _x_i3
-        in
-          {
-            switch_case = _x;
-            switch_body = _x_i1;
-            should_break = _x_i2;
-            comment = _x_i3;
-          }
-    method block : block -> block = (* true means break *)
+      (* true means break *)
       (* TODO: For efficency: block should not be a list, it should be able to 
    be concatenated in both ways 
  *)
@@ -108512,7 +108498,7 @@ let eval (arg : J.expression) (dispatches : (string * string) list ) : E.t =
       E.of_block
         [(S.string_switch arg
             (Ext_list.map dispatches (fun (i,r) ->
-                 {J.switch_case = i ;
+                 i, J.{
                   switch_body = [S.return_stmt (E.str r)];
                   should_break = false; (* FIXME: if true, still print break*)
                   comment = None;
@@ -108540,7 +108526,7 @@ let eval_as_event (arg : J.expression) (dispatches : (string * string) list opti
       
         (S.string_switch (E.poly_var_tag_access arg)
         (Ext_list.map dispatches (fun (i,r) ->
-              {J.switch_case = i ;
+              i, J.{
                switch_body = [S.return_stmt (E.str r)];
                should_break = false; (* FIXME: if true, still print break*)
                comment = None;
@@ -108572,7 +108558,7 @@ let eval_as_int (arg : J.expression) (dispatches : (string * int) list ) : E.t
     E.of_block
       [(S.string_switch arg
       (Ext_list.map dispatches (fun (i,r) ->
-              {J.switch_case = i ;
+              i, J.{
                switch_body = [S.return_stmt (E.int (Int32.of_int  r))];
                should_break = false; (* FIXME: if true, still print break*)
                comment = None;
@@ -113747,7 +113733,7 @@ and compile_general_cases
   Lam_compile_context.t ->
   (?default:J.block ->
    ?declaration:Lam_compat.let_kind * Ident.t  ->
-   _ -> 'a J.case_clause list ->  J.statement) ->
+   _ -> ('a * J.case_clause) list ->  J.statement) ->
   _ ->
   ('a * Lam.t) list -> default_case -> J.block
   = fun
@@ -113758,7 +113744,7 @@ and compile_general_cases
   (switch :
   ?default:J.block ->
    ?declaration:Lam_compat.let_kind * Ident.t  ->
-   _ -> _ J.case_clause list ->  J.statement
+   _ -> (_ * J.case_clause) list ->  J.statement
    )
    (switch_exp : J.expression)
    (cases : (_ * Lam.t) list)
@@ -113828,13 +113814,13 @@ and compile_general_cases
                               should_break
                             else
                               should_break && Lam_exit_code.has_exit lam in
-                        {J.switch_case ;
+                          switch_case , J.{
                             switch_body;
                             should_break;
                             comment = make_comment switch_case;
                         }
                       else
-                        { switch_case; switch_body = []; should_break = false; comment = make_comment switch_case; }
+                      switch_case, {switch_body = []; should_break = false; comment = make_comment switch_case; }
                     )                   
               
               (* TODO: we should also group default *)
diff --git a/lib/4.06.1/unstable/js_refmt_compiler.ml b/lib/4.06.1/unstable/js_refmt_compiler.ml
index 4d6379de0b..ddebc15981 100644
--- a/lib/4.06.1/unstable/js_refmt_compiler.ml
+++ b/lib/4.06.1/unstable/js_refmt_compiler.ml
@@ -86060,8 +86060,8 @@ and statement_desc =
     {[ goto : label option ; ]}
   *)
 
-  | Int_switch of expression * int case_clause list * block option 
-  | String_switch of expression * string case_clause list * block option 
+  | Int_switch of expression * int_clause list * block option 
+  | String_switch of expression * string_clause list * block option 
   | Throw of expression
   | Try of block * (exception_ident * block) option * block option
   | Debugger
@@ -86084,9 +86084,9 @@ and variable_declaration = {
   property : property;
   ident_info : ident_info;
 }
-
-and 'a case_clause = { 
-  switch_case : 'a ; 
+and string_clause = string * case_clause
+and int_clause =  int * case_clause
+and case_clause = {   
   switch_body : block ;
   should_break :  bool ;  (* true means break *)
   comment : string option ;
@@ -86557,6 +86557,9 @@ class virtual fold =
         let o = o#option (fun o -> o#expression) _x_i1 in
         let o = o#property _x_i2 in let o = o#ident_info _x_i3 in o
     method tag_info : tag_info -> 'self_type = o#unknown
+    method string_clause : string_clause -> 'self_type =
+      fun (_x, _x_i1) ->
+        let o = o#string _x in let o = o#case_clause _x_i1 in o
     method statement_desc : statement_desc -> 'self_type =
       function
       | Block _x -> let o = o#block _x in o
@@ -86580,10 +86583,28 @@ class virtual fold =
       | Return _x -> let o = o#expression _x in o
       | Int_switch (_x, _x_i1, _x_i2) ->
           let o = o#expression _x in
+          let o = o#list (fun o -> o#int_clause) _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | String_switch (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#list (fun o -> o#string_clause) _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | Throw _x -> let o = o#expression _x in o
+      | Try (_x, _x_i1, _x_i2) ->
+          let o = o#block _x in
           let o =
-            o#list
-              (fun o ->
-                 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+            o#option
+              (fun o (_x, _x_i1) ->
+                 let o = o#exception_ident _x in let o = o#block _x_i1 in o)
+              _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | Debugger -> o
+    method statement : statement -> 'self_type =
+      fun { statement_desc = _x; comment = _x_i1 } ->
+        let o = o#statement_desc _x in
+        let o = o#option (fun o -> o#string) _x_i1 in o
+    method required_modules : required_modules -> 'self_type =
+      (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
  * 
  * 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
@@ -86606,7 +86627,7 @@ class virtual fold =
  * 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. *)
-                 (* Javascript IR
+      (* Javascript IR
   
     It's a subset of Javascript AST specialized for OCaml lambda backend
 
@@ -86614,15 +86635,18 @@ class virtual fold =
     convention and [Block] is just a sequence of statements, which means it does 
     not introduce new scope
 *)
-                 (* TODO: it seems that camlp4of supports very limited structures
+      (* TODO: it seems that camlp4of supports very limited structures
    it does not even support attributes like `[@@@warning "-30"]
    we should get rid of such dependency ASAP
 *)
-                 (** object literal, if key is ident, in this case, it might be renamed by 
+      o#list (fun o -> o#module_id)
+    method property_name : property_name -> 'self_type = o#unknown
+    method property_map : property_map -> 'self_type =
+      (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-                 (* Since camldot is only available for toplevel module accessors,
+      (* Since camldot is only available for toplevel module accessors,
        we don't need print  `A.length$2`
        just print `A.length` - it's guarateed to be unique
        
@@ -86637,7 +86661,74 @@ class virtual fold =
          Qualified (_, Runtime, Some "caml_int_compare")         
        ]}       
      *)
-                 (** where we use a trick [== null ] *) (* js true/false*)
+      o#list
+        (fun o (_x, _x_i1) ->
+           let o = o#property_name _x in let o = o#expression _x_i1 in o)
+    method property : property -> 'self_type = o#unknown
+    method program : program -> 'self_type =
+      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
+        let o = o#block _x in
+        let o = o#exports _x_i1 in let o = o#unknown _x_i2 in o
+    method number : number -> 'self_type = o#unknown
+    method mutable_flag : mutable_flag -> 'self_type = o#unknown
+    method module_id : module_id -> 'self_type =
+      fun { id = _x; kind = _x_i1 } ->
+        let o = o#ident _x in let o = o#unknown _x_i1 in o
+    method length_object : length_object -> 'self_type = o#unknown
+    method label : label -> 'self_type = o#string
+    method kind : kind -> 'self_type = o#unknown
+    method jsint : jsint -> 'self_type = o#int32
+    method int_op : int_op -> 'self_type = o#unknown
+    method int_clause : int_clause -> 'self_type =
+      fun (_x, _x_i1) -> let o = o#int _x in let o = o#case_clause _x_i1 in o
+    method ident_info : ident_info -> 'self_type = o#unknown
+    method ident : ident -> 'self_type = o#unknown
+    method for_ident_expression : for_ident_expression -> 'self_type =
+      o#expression
+    method for_ident : for_ident -> 'self_type = o#ident
+    method for_direction : for_direction -> 'self_type = o#unknown
+    method finish_ident_expression : finish_ident_expression -> 'self_type =
+      o#expression
+    method expression_desc : expression_desc -> 'self_type =
+      function
+      | Length (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#length_object _x_i1 in o
+      | Char_of_int _x -> let o = o#expression _x in o
+      | Char_to_int _x -> let o = o#expression _x in o
+      | Is_null_or_undefined _x -> let o = o#expression _x in o
+      | String_append (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Bool _x -> let o = o#bool _x in o
+      | Typeof _x -> let o = o#expression _x in o
+      | Js_not _x -> let o = o#expression _x in o
+      | Seq (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Cond (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
+      | Bin (_x, _x_i1, _x_i2) ->
+          let o = o#binop _x in
+          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
+      | FlatCall (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Call (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#list (fun o -> o#expression) _x_i1 in
+          let o = o#unknown _x_i2 in o
+      | String_index (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Array_index (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Static_index (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#string _x_i1 in
+          let o = o#option (fun o -> o#int32) _x_i2 in o
+      | New (_x, _x_i1) ->
+          let o = o#expression _x in
+          let o =
+            o#option
+              (fun o -> (** where we use a trick [== null ] *)
+                 (* js true/false*)
                  (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence 
      [typeof] is an operator     
   *)
@@ -86672,11 +86763,52 @@ class virtual fold =
           All exported declarations have to be OCaml identifiers
        2. Javascript dot (need to be preserved/or using quote)
      *)
-                 (* TODO: option remove *)
-                 (* The first parameter by default is false, 
+                 o#list (fun o -> o#expression))
+              _x_i1
+          in o
+      | Var _x -> let o = o#vident _x in o
+      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
+          let o = o#bool _x in
+          let o = o#list (fun o -> o#ident) _x_i1 in
+          let o = o#block _x_i2 in let o = o#unknown _x_i3 in o
+      | Str (_x, _x_i1) -> let o = o#bool _x in let o = o#string _x_i1 in o
+      | Unicode _x -> let o = o#string _x in o
+      | Raw_js_code _x -> let o = o#unknown _x in o
+      | Array (_x, _x_i1) ->
+          let o = o#list (fun o -> o#expression) _x in
+          let o = o#mutable_flag _x_i1 in o
+      | Optional_block (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#bool _x_i1 in o
+      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
+          let o = o#list (fun o -> o#expression) _x in
+          let o = o#mutable_flag _x_i1 in
+          let o = o#expression _x_i2 in let o = o#tag_info _x_i3 in o
+      | Caml_block_tag _x -> let o = o#expression _x in o
+      | Number _x -> let o = o#number _x in o
+      | Object _x -> let o = o#property_map _x in o
+      | Undefined -> o
+      | Null -> o
+    method expression : expression -> 'self_type =
+      fun { expression_desc = _x; comment = _x_i1 } ->
+        let o = o#expression_desc _x in
+        let o = o#option (fun o -> o#string) _x_i1 in o
+    method exports : exports -> 'self_type = o#unknown
+    method exception_ident : exception_ident -> 'self_type = o#ident
+    method deps_program : deps_program -> 'self_type =
+      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
+        let o = o#program _x in
+        let o = o#required_modules _x_i1 in
+        let o = o#option (fun o -> o#string) _x_i2 in o
+    method case_clause : case_clause -> 'self_type =
+      fun { switch_body = _x; should_break = _x_i1; comment = _x_i2 } ->
+        let o = o#block _x in
+        let o = o#bool _x_i1 in
+        let o = o#option (fun o -> o#string) _x_i2 in o
+    method block : block -> 'self_type = (* TODO: option remove *)
+      (* The first parameter by default is false, 
      it will be true when it's a method
   *)
-                 (* A string is UTF-8 encoded, the string may contain
+      (* A string is UTF-8 encoded, the string may contain
        escape sequences.
        The first argument is used to mark it is non-pure, please
        don't optimize it, since it does have side effec, 
@@ -86684,13 +86816,13 @@ class virtual fold =
        which is better to leave it alone
        The last argument is passed from as `j` from `{j||j}`
      *)
-                 (* It is escaped string, print delimited by '"'*)
-                 (* literally raw JS code 
+      (* It is escaped string, print delimited by '"'*)
+      (* literally raw JS code 
   *) (* [true] means [identity] *)
-                 (* The third argument is [tag] , forth is [tag_info] *)
-                 (* | Caml_uninitialized_obj of expression * expression *)
-                 (* [tag] and [size] tailed  for [Obj.new_block] *)
-                 (* For setter, it still return the value of expression, 
+      (* The third argument is [tag] , forth is [tag_info] *)
+      (* | Caml_uninitialized_obj of expression * expression *)
+      (* [tag] and [size] tailed  for [Obj.new_block] *)
+      (* For setter, it still return the value of expression, 
      we can not use 
      {[
        type 'a access = Get | Set of 'a
@@ -86699,20 +86831,20 @@ class virtual fold =
      [Caml_block_tag] can return [undefined], 
      you have to use [E.tag] in a safe way     
   *)
-                 (* | Caml_block_set_tag of expression * expression *)
-                 (* | Caml_block_set_length of expression * expression *)
-                 (* It will just fetch tag, to make it safe, when creating it, 
+      (* | Caml_block_set_tag of expression * expression *)
+      (* | Caml_block_set_length of expression * expression *)
+      (* It will just fetch tag, to make it safe, when creating it, 
      we need apply "|0", we don't do it in the 
      last step since "|0" can potentially be optimized
   *)
-                 (* pure*) (* pure *)
-                 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
+      (* pure*) (* pure *)
+      (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
    block can be nested, specified in ES3 
  *)
-                 (* Delay some units like [primitive] into JS layer ,
+      (* Delay some units like [primitive] into JS layer ,
    benefit: better cross module inlining, and smaller IR size?
  *)
-                 (* 
+      (* 
   [closure] captured loop mutable values in the outer loop
 
   check if it contains loop mutable values, happens in nested loop
@@ -86738,7 +86870,7 @@ class virtual fold =
   contains a block side effect
   TODO: create such example
 *)
-                 (* Since in OCaml, 
+      (* Since in OCaml, 
    
   [for i = 0 to k end do done ]
   k is only evaluated once , to encode this invariant in JS IR,
@@ -86747,7 +86879,7 @@ class virtual fold =
   TODO: currently we guarantee that [bound] was only 
   excecuted once, should encode this in AST level
 *)
-                 (* Can be simplified to keep the semantics of OCaml
+      (* Can be simplified to keep the semantics of OCaml
    For (var i, e, ...){
      let  j = ... 
    }
@@ -86759,7 +86891,7 @@ class virtual fold =
      })(i)
    }
 *)
-                 (* Single return is good for ininling..
+      (* Single return is good for ininling..
    However, when you do tail-call optmization
    you loose the expression oriented semantics
    Block is useful for implementing goto
@@ -86769,12 +86901,12 @@ class virtual fold =
    }
    ]}
 *)
-                 (* Function declaration and Variable declaration  *)
-                 (* check if it contains loop mutable values, happens in nested loop *)
-                 (* only used when inline a fucntion *)
-                 (* Here we need track back a bit ?, move Return to Function ...
+      (* Function declaration and Variable declaration  *)
+      (* check if it contains loop mutable values, happens in nested loop *)
+      (* only used when inline a fucntion *)
+      (* Here we need track back a bit ?, move Return to Function ...
                               Then we can only have one Return, which is not good *)
-                 (* since in ocaml, it's expression oriented langauge, [return] in
+      (* since in ocaml, it's expression oriented langauge, [return] in
     general has no jumps, it only happens when we do 
     tailcall conversion, in that case there is a jump.
     However, currently  a single [break] is good to cover
@@ -86784,143 +86916,7 @@ class virtual fold =
     A more robust signature would be 
     {[ goto : label option ; ]}
   *)
-                 o#case_clause (fun o -> o#int))
-              _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | String_switch (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o =
-            o#list (fun o -> o#case_clause (fun o -> o#string)) _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | Throw _x -> let o = o#expression _x in o
-      | Try (_x, _x_i1, _x_i2) ->
-          let o = o#block _x in
-          let o =
-            o#option
-              (fun o (_x, _x_i1) ->
-                 let o = o#exception_ident _x in let o = o#block _x_i1 in o)
-              _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | Debugger -> o
-    method statement : statement -> 'self_type =
-      fun { statement_desc = _x; comment = _x_i1 } ->
-        let o = o#statement_desc _x in
-        let o = o#option (fun o -> o#string) _x_i1 in o
-    method required_modules : required_modules -> 'self_type =
-      o#list (fun o -> o#module_id)
-    method property_name : property_name -> 'self_type = o#unknown
-    method property_map : property_map -> 'self_type =
-      o#list
-        (fun o (_x, _x_i1) ->
-           let o = o#property_name _x in let o = o#expression _x_i1 in o)
-    method property : property -> 'self_type = o#unknown
-    method program : program -> 'self_type =
-      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
-        let o = o#block _x in
-        let o = o#exports _x_i1 in let o = o#unknown _x_i2 in o
-    method number : number -> 'self_type = o#unknown
-    method mutable_flag : mutable_flag -> 'self_type = o#unknown
-    method module_id : module_id -> 'self_type =
-      fun { id = _x; kind = _x_i1 } ->
-        let o = o#ident _x in let o = o#unknown _x_i1 in o
-    method length_object : length_object -> 'self_type = o#unknown
-    method label : label -> 'self_type = o#string
-    method kind : kind -> 'self_type = o#unknown
-    method jsint : jsint -> 'self_type = o#int32
-    method int_op : int_op -> 'self_type = o#unknown
-    method ident_info : ident_info -> 'self_type = o#unknown
-    method ident : ident -> 'self_type = o#unknown
-    method for_ident_expression : for_ident_expression -> 'self_type =
-      o#expression
-    method for_ident : for_ident -> 'self_type = o#ident
-    method for_direction : for_direction -> 'self_type = o#unknown
-    method finish_ident_expression : finish_ident_expression -> 'self_type =
-      o#expression
-    method expression_desc : expression_desc -> 'self_type =
-      function
-      | Length (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#length_object _x_i1 in o
-      | Char_of_int _x -> let o = o#expression _x in o
-      | Char_to_int _x -> let o = o#expression _x in o
-      | Is_null_or_undefined _x -> let o = o#expression _x in o
-      | String_append (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Bool _x -> let o = o#bool _x in o
-      | Typeof _x -> let o = o#expression _x in o
-      | Js_not _x -> let o = o#expression _x in o
-      | Seq (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Cond (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
-      | Bin (_x, _x_i1, _x_i2) ->
-          let o = o#binop _x in
-          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
-      | FlatCall (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Call (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#list (fun o -> o#expression) _x_i1 in
-          let o = o#unknown _x_i2 in o
-      | String_index (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Array_index (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Static_index (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#string _x_i1 in
-          let o = o#option (fun o -> o#int32) _x_i2 in o
-      | New (_x, _x_i1) ->
-          let o = o#expression _x in
-          let o = o#option (fun o -> o#list (fun o -> o#expression)) _x_i1
-          in o
-      | Var _x -> let o = o#vident _x in o
-      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
-          let o = o#bool _x in
-          let o = o#list (fun o -> o#ident) _x_i1 in
-          let o = o#block _x_i2 in let o = o#unknown _x_i3 in o
-      | Str (_x, _x_i1) -> let o = o#bool _x in let o = o#string _x_i1 in o
-      | Unicode _x -> let o = o#string _x in o
-      | Raw_js_code _x -> let o = o#unknown _x in o
-      | Array (_x, _x_i1) ->
-          let o = o#list (fun o -> o#expression) _x in
-          let o = o#mutable_flag _x_i1 in o
-      | Optional_block (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#bool _x_i1 in o
-      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
-          let o = o#list (fun o -> o#expression) _x in
-          let o = o#mutable_flag _x_i1 in
-          let o = o#expression _x_i2 in let o = o#tag_info _x_i3 in o
-      | Caml_block_tag _x -> let o = o#expression _x in o
-      | Number _x -> let o = o#number _x in o
-      | Object _x -> let o = o#property_map _x in o
-      | Undefined -> o
-      | Null -> o
-    method expression : expression -> 'self_type =
-      fun { expression_desc = _x; comment = _x_i1 } ->
-        let o = o#expression_desc _x in
-        let o = o#option (fun o -> o#string) _x_i1 in o
-    method exports : exports -> 'self_type = o#unknown
-    method exception_ident : exception_ident -> 'self_type = o#ident
-    method deps_program : deps_program -> 'self_type =
-      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
-        let o = o#program _x in
-        let o = o#required_modules _x_i1 in
-        let o = o#option (fun o -> o#string) _x_i2 in o
-    method case_clause :
-      'a. ('self_type -> 'a -> 'self_type) -> 'a case_clause -> 'self_type =
-      fun _f_a
-        {
-          switch_case = _x;
-          switch_body = _x_i1;
-          should_break = _x_i2;
-          comment = _x_i3
-        } ->
-        let o = _f_a o _x in
-        let o = o#block _x_i1 in
-        let o = o#bool _x_i2 in
-        let o = o#option (fun o -> o#string) _x_i3 in o
-    method block : block -> 'self_type = (* true means break *)
+      (* true means break *)
       (* TODO: For efficency: block should not be a list, it should be able to 
    be concatenated in both ways 
  *)
@@ -90313,9 +90309,9 @@ and  pp_function ~is_method
     since it can be either [int] or [string]
 *)
 and pp_one_case_clause : 'a .
-  _ -> P.t -> (P.t -> 'a -> unit) -> 'a J.case_clause -> _
+  _ -> P.t -> (P.t -> 'a -> unit) -> ('a * J.case_clause) -> _
   = fun cxt f  pp_cond
-    ({switch_case; switch_body ; should_break; comment; } : _ J.case_clause) ->
+    (switch_case, ({switch_body ; should_break; comment; } :  J.case_clause)) ->
     let cxt =
       P.group f 1  (fun _ ->
           P.group f 1 (fun _ ->
@@ -90345,7 +90341,7 @@ and pp_one_case_clause : 'a .
     cxt
 
 and loop_case_clauses  :  'a . cxt ->
-  P.t -> (P.t -> 'a -> unit) -> 'a J.case_clause list -> cxt
+  P.t -> (P.t -> 'a -> unit) -> ('a * J.case_clause) list -> cxt
   = fun  cxt  f pp_cond cases ->
     Ext_list.fold_left cases cxt (fun acc x -> pp_one_case_clause acc f pp_cond x)              
 
@@ -99589,7 +99585,7 @@ val int_switch :
   ?declaration:Lam_compat.let_kind * Ident.t -> 
   ?default:J.block -> 
   J.expression -> 
-  int J.case_clause list -> 
+  (int * J.case_clause) list -> 
   t 
 
 val string_switch : 
@@ -99597,7 +99593,7 @@ val string_switch :
   ?declaration:Lam_compat.let_kind * Ident.t -> 
   ?default:J.block ->
   J.expression -> 
-  string J.case_clause list ->
+  (string * J.case_clause) list ->
   t
 
 (** Just declaration without initialization *)  
@@ -99807,13 +99803,13 @@ let int_switch
     ?(declaration : (J.property * Ident.t) option )
     ?(default : J.block option)
     (e : J.expression)  
-    (clauses : int J.case_clause list): t = 
+    (clauses : (int * J.case_clause) list): t = 
   match e.expression_desc with 
   | Number (Int {i; _}) -> 
     let continuation =  
       match Ext_list.find_opt clauses
-              (fun x ->
-                 if x.switch_case = Int32.to_int i then
+              (fun (switch_case,x) ->
+                 if switch_case = Int32.to_int i then
                    Some x.switch_body else None ) 
       with 
       | Some case -> case 
@@ -99846,12 +99842,12 @@ let string_switch
   ?(declaration : (J.property * Ident.t) option) 
   ?(default : J.block option)
   (e : J.expression)  
-  (clauses : string J.case_clause list): t= 
+  (clauses : (string * J.case_clause) list): t= 
   match e.expression_desc with 
   | Str (_,s) -> 
     let continuation = 
-      match Ext_list.find_opt clauses (fun  x ->
-                 if x.switch_case = s then 
+      match Ext_list.find_opt clauses (fun  (switch_case, x) ->
+                 if switch_case = s then 
                    Some x.switch_body
                  else None  
               ) with 
@@ -101742,6 +101738,10 @@ class virtual map =
           { ident = _x; value = _x_i1; property = _x_i2; ident_info = _x_i3;
           }
     method tag_info : tag_info -> tag_info = o#unknown
+    method string_clause : string_clause -> string_clause =
+      fun (_x, _x_i1) ->
+        let _x = o#string _x in
+        let _x_i1 = o#case_clause _x_i1 in (_x, _x_i1)
     method statement_desc : statement_desc -> statement_desc =
       function
       | Block _x -> let _x = o#block _x in Block _x
@@ -101769,14 +101769,37 @@ class virtual map =
       | Return _x -> let _x = o#expression _x in Return _x
       | Int_switch (_x, _x_i1, _x_i2) ->
           let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#int_clause) _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in Int_switch (_x, _x_i1, _x_i2)
+      | String_switch (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#string_clause) _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in String_switch (_x, _x_i1, _x_i2)
+      | Throw _x -> let _x = o#expression _x in Throw _x
+      | Try (_x, _x_i1, _x_i2) ->
+          let _x = o#block _x in
           let _x_i1 =
-            o#list
-              (fun o ->
-                 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
- * 
- * 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
+            o#option
+              (fun o (_x, _x_i1) ->
+                 let _x = o#exception_ident _x in
+                 let _x_i1 = o#block _x_i1 in (_x, _x_i1))
+              _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in Try (_x, _x_i1, _x_i2)
+      | Debugger -> Debugger
+    method statement : statement -> statement =
+      fun { statement_desc = _x; comment = _x_i1 } ->
+        let _x = o#statement_desc _x in
+        let _x_i1 = o#option (fun o -> o#string) _x_i1
+        in { statement_desc = _x; comment = _x_i1; }
+    method required_modules : required_modules -> required_modules =
+      (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * 
+ * 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
@@ -101795,7 +101818,7 @@ class virtual map =
  * 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. *)
-                 (* Javascript IR
+      (* Javascript IR
   
     It's a subset of Javascript AST specialized for OCaml lambda backend
 
@@ -101803,15 +101826,18 @@ class virtual map =
     convention and [Block] is just a sequence of statements, which means it does 
     not introduce new scope
 *)
-                 (* TODO: it seems that camlp4of supports very limited structures
+      (* TODO: it seems that camlp4of supports very limited structures
    it does not even support attributes like `[@@@warning "-30"]
    we should get rid of such dependency ASAP
 *)
-                 (** object literal, if key is ident, in this case, it might be renamed by 
+      o#list (fun o -> o#module_id)
+    method property_name : property_name -> property_name = o#unknown
+    method property_map : property_map -> property_map =
+      (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-                 (* Since camldot is only available for toplevel module accessors,
+      (* Since camldot is only available for toplevel module accessors,
        we don't need print  `A.length$2`
        just print `A.length` - it's guarateed to be unique
        
@@ -101826,7 +101852,89 @@ class virtual map =
          Qualified (_, Runtime, Some "caml_int_compare")         
        ]}       
      *)
-                 (** where we use a trick [== null ] *) (* js true/false*)
+      o#list
+        (fun o (_x, _x_i1) ->
+           let _x = o#property_name _x in
+           let _x_i1 = o#expression _x_i1 in (_x, _x_i1))
+    method property : property -> property = o#unknown
+    method program : program -> program =
+      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
+        let _x = o#block _x in
+        let _x_i1 = o#exports _x_i1 in
+        let _x_i2 = o#unknown _x_i2
+        in { block = _x; exports = _x_i1; export_set = _x_i2; }
+    method number : number -> number = o#unknown
+    method mutable_flag : mutable_flag -> mutable_flag = o#unknown
+    method module_id : module_id -> module_id =
+      fun { id = _x; kind = _x_i1 } ->
+        let _x = o#ident _x in
+        let _x_i1 = o#unknown _x_i1 in { id = _x; kind = _x_i1; }
+    method length_object : length_object -> length_object = o#unknown
+    method label : label -> label = o#string
+    method kind : kind -> kind = o#unknown
+    method jsint : jsint -> jsint = o#int32
+    method int_op : int_op -> int_op = o#unknown
+    method int_clause : int_clause -> int_clause =
+      fun (_x, _x_i1) ->
+        let _x = o#int _x in let _x_i1 = o#case_clause _x_i1 in (_x, _x_i1)
+    method ident_info : ident_info -> ident_info = o#unknown
+    method ident : ident -> ident = o#unknown
+    method for_ident_expression :
+      for_ident_expression -> for_ident_expression = o#expression
+    method for_ident : for_ident -> for_ident = o#ident
+    method for_direction : for_direction -> for_direction = o#unknown
+    method finish_ident_expression :
+      finish_ident_expression -> finish_ident_expression = o#expression
+    method expression_desc : expression_desc -> expression_desc =
+      function
+      | Length (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#length_object _x_i1 in Length (_x, _x_i1)
+      | Char_of_int _x -> let _x = o#expression _x in Char_of_int _x
+      | Char_to_int _x -> let _x = o#expression _x in Char_to_int _x
+      | Is_null_or_undefined _x ->
+          let _x = o#expression _x in Is_null_or_undefined _x
+      | String_append (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in String_append (_x, _x_i1)
+      | Bool _x -> let _x = o#bool _x in Bool _x
+      | Typeof _x -> let _x = o#expression _x in Typeof _x
+      | Js_not _x -> let _x = o#expression _x in Js_not _x
+      | Seq (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in Seq (_x, _x_i1)
+      | Cond (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in
+          let _x_i2 = o#expression _x_i2 in Cond (_x, _x_i1, _x_i2)
+      | Bin (_x, _x_i1, _x_i2) ->
+          let _x = o#binop _x in
+          let _x_i1 = o#expression _x_i1 in
+          let _x_i2 = o#expression _x_i2 in Bin (_x, _x_i1, _x_i2)
+      | FlatCall (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in FlatCall (_x, _x_i1)
+      | Call (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#expression) _x_i1 in
+          let _x_i2 = o#unknown _x_i2 in Call (_x, _x_i1, _x_i2)
+      | String_index (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in String_index (_x, _x_i1)
+      | Array_index (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in Array_index (_x, _x_i1)
+      | Static_index (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#string _x_i1 in
+          let _x_i2 = o#option (fun o -> o#int32) _x_i2
+          in Static_index (_x, _x_i1, _x_i2)
+      | New (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 =
+            o#option
+              (fun o -> (** where we use a trick [== null ] *)
+                 (* js true/false*)
                  (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence 
      [typeof] is an operator     
   *)
@@ -101861,11 +101969,60 @@ class virtual map =
           All exported declarations have to be OCaml identifiers
        2. Javascript dot (need to be preserved/or using quote)
      *)
-                 (* TODO: option remove *)
-                 (* The first parameter by default is false, 
+                 o#list (fun o -> o#expression))
+              _x_i1
+          in New (_x, _x_i1)
+      | Var _x -> let _x = o#vident _x in Var _x
+      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
+          let _x = o#bool _x in
+          let _x_i1 = o#list (fun o -> o#ident) _x_i1 in
+          let _x_i2 = o#block _x_i2 in
+          let _x_i3 = o#unknown _x_i3 in Fun (_x, _x_i1, _x_i2, _x_i3)
+      | Str (_x, _x_i1) ->
+          let _x = o#bool _x in let _x_i1 = o#string _x_i1 in Str (_x, _x_i1)
+      | Unicode _x -> let _x = o#string _x in Unicode _x
+      | Raw_js_code _x -> let _x = o#unknown _x in Raw_js_code _x
+      | Array (_x, _x_i1) ->
+          let _x = o#list (fun o -> o#expression) _x in
+          let _x_i1 = o#mutable_flag _x_i1 in Array (_x, _x_i1)
+      | Optional_block (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#bool _x_i1 in Optional_block (_x, _x_i1)
+      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
+          let _x = o#list (fun o -> o#expression) _x in
+          let _x_i1 = o#mutable_flag _x_i1 in
+          let _x_i2 = o#expression _x_i2 in
+          let _x_i3 = o#tag_info _x_i3
+          in Caml_block (_x, _x_i1, _x_i2, _x_i3)
+      | Caml_block_tag _x -> let _x = o#expression _x in Caml_block_tag _x
+      | Number _x -> let _x = o#number _x in Number _x
+      | Object _x -> let _x = o#property_map _x in Object _x
+      | Undefined -> Undefined
+      | Null -> Null
+    method expression : expression -> expression =
+      fun { expression_desc = _x; comment = _x_i1 } ->
+        let _x = o#expression_desc _x in
+        let _x_i1 = o#option (fun o -> o#string) _x_i1
+        in { expression_desc = _x; comment = _x_i1; }
+    method exports : exports -> exports = o#unknown
+    method exception_ident : exception_ident -> exception_ident = o#ident
+    method deps_program : deps_program -> deps_program =
+      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
+        let _x = o#program _x in
+        let _x_i1 = o#required_modules _x_i1 in
+        let _x_i2 = o#option (fun o -> o#string) _x_i2
+        in { program = _x; modules = _x_i1; side_effect = _x_i2; }
+    method case_clause : case_clause -> case_clause =
+      fun { switch_body = _x; should_break = _x_i1; comment = _x_i2 } ->
+        let _x = o#block _x in
+        let _x_i1 = o#bool _x_i1 in
+        let _x_i2 = o#option (fun o -> o#string) _x_i2
+        in { switch_body = _x; should_break = _x_i1; comment = _x_i2; }
+    method block : block -> block = (* TODO: option remove *)
+      (* The first parameter by default is false, 
      it will be true when it's a method
   *)
-                 (* A string is UTF-8 encoded, the string may contain
+      (* A string is UTF-8 encoded, the string may contain
        escape sequences.
        The first argument is used to mark it is non-pure, please
        don't optimize it, since it does have side effec, 
@@ -101873,13 +102030,13 @@ class virtual map =
        which is better to leave it alone
        The last argument is passed from as `j` from `{j||j}`
      *)
-                 (* It is escaped string, print delimited by '"'*)
-                 (* literally raw JS code 
+      (* It is escaped string, print delimited by '"'*)
+      (* literally raw JS code 
   *) (* [true] means [identity] *)
-                 (* The third argument is [tag] , forth is [tag_info] *)
-                 (* | Caml_uninitialized_obj of expression * expression *)
-                 (* [tag] and [size] tailed  for [Obj.new_block] *)
-                 (* For setter, it still return the value of expression, 
+      (* The third argument is [tag] , forth is [tag_info] *)
+      (* | Caml_uninitialized_obj of expression * expression *)
+      (* [tag] and [size] tailed  for [Obj.new_block] *)
+      (* For setter, it still return the value of expression, 
      we can not use 
      {[
        type 'a access = Get | Set of 'a
@@ -101888,20 +102045,20 @@ class virtual map =
      [Caml_block_tag] can return [undefined], 
      you have to use [E.tag] in a safe way     
   *)
-                 (* | Caml_block_set_tag of expression * expression *)
-                 (* | Caml_block_set_length of expression * expression *)
-                 (* It will just fetch tag, to make it safe, when creating it, 
+      (* | Caml_block_set_tag of expression * expression *)
+      (* | Caml_block_set_length of expression * expression *)
+      (* It will just fetch tag, to make it safe, when creating it, 
      we need apply "|0", we don't do it in the 
      last step since "|0" can potentially be optimized
   *)
-                 (* pure*) (* pure *)
-                 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
+      (* pure*) (* pure *)
+      (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
    block can be nested, specified in ES3 
  *)
-                 (* Delay some units like [primitive] into JS layer ,
+      (* Delay some units like [primitive] into JS layer ,
    benefit: better cross module inlining, and smaller IR size?
  *)
-                 (* 
+      (* 
   [closure] captured loop mutable values in the outer loop
 
   check if it contains loop mutable values, happens in nested loop
@@ -101927,7 +102084,7 @@ class virtual map =
   contains a block side effect
   TODO: create such example
 *)
-                 (* Since in OCaml, 
+      (* Since in OCaml, 
    
   [for i = 0 to k end do done ]
   k is only evaluated once , to encode this invariant in JS IR,
@@ -101936,7 +102093,7 @@ class virtual map =
   TODO: currently we guarantee that [bound] was only 
   excecuted once, should encode this in AST level
 *)
-                 (* Can be simplified to keep the semantics of OCaml
+      (* Can be simplified to keep the semantics of OCaml
    For (var i, e, ...){
      let  j = ... 
    }
@@ -101948,7 +102105,7 @@ class virtual map =
      })(i)
    }
 *)
-                 (* Single return is good for ininling..
+      (* Single return is good for ininling..
    However, when you do tail-call optmization
    you loose the expression oriented semantics
    Block is useful for implementing goto
@@ -101958,12 +102115,12 @@ class virtual map =
    }
    ]}
 *)
-                 (* Function declaration and Variable declaration  *)
-                 (* check if it contains loop mutable values, happens in nested loop *)
-                 (* only used when inline a fucntion *)
-                 (* Here we need track back a bit ?, move Return to Function ...
+      (* Function declaration and Variable declaration  *)
+      (* check if it contains loop mutable values, happens in nested loop *)
+      (* only used when inline a fucntion *)
+      (* Here we need track back a bit ?, move Return to Function ...
                               Then we can only have one Return, which is not good *)
-                 (* since in ocaml, it's expression oriented langauge, [return] in
+      (* since in ocaml, it's expression oriented langauge, [return] in
     general has no jumps, it only happens when we do 
     tailcall conversion, in that case there is a jump.
     However, currently  a single [break] is good to cover
@@ -101973,178 +102130,7 @@ class virtual map =
     A more robust signature would be 
     {[ goto : label option ; ]}
   *)
-                 o#case_clause (fun o -> o#int))
-              _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in Int_switch (_x, _x_i1, _x_i2)
-      | String_switch (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 =
-            o#list (fun o -> o#case_clause (fun o -> o#string)) _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in String_switch (_x, _x_i1, _x_i2)
-      | Throw _x -> let _x = o#expression _x in Throw _x
-      | Try (_x, _x_i1, _x_i2) ->
-          let _x = o#block _x in
-          let _x_i1 =
-            o#option
-              (fun o (_x, _x_i1) ->
-                 let _x = o#exception_ident _x in
-                 let _x_i1 = o#block _x_i1 in (_x, _x_i1))
-              _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in Try (_x, _x_i1, _x_i2)
-      | Debugger -> Debugger
-    method statement : statement -> statement =
-      fun { statement_desc = _x; comment = _x_i1 } ->
-        let _x = o#statement_desc _x in
-        let _x_i1 = o#option (fun o -> o#string) _x_i1
-        in { statement_desc = _x; comment = _x_i1; }
-    method required_modules : required_modules -> required_modules =
-      o#list (fun o -> o#module_id)
-    method property_name : property_name -> property_name = o#unknown
-    method property_map : property_map -> property_map =
-      o#list
-        (fun o (_x, _x_i1) ->
-           let _x = o#property_name _x in
-           let _x_i1 = o#expression _x_i1 in (_x, _x_i1))
-    method property : property -> property = o#unknown
-    method program : program -> program =
-      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
-        let _x = o#block _x in
-        let _x_i1 = o#exports _x_i1 in
-        let _x_i2 = o#unknown _x_i2
-        in { block = _x; exports = _x_i1; export_set = _x_i2; }
-    method number : number -> number = o#unknown
-    method mutable_flag : mutable_flag -> mutable_flag = o#unknown
-    method module_id : module_id -> module_id =
-      fun { id = _x; kind = _x_i1 } ->
-        let _x = o#ident _x in
-        let _x_i1 = o#unknown _x_i1 in { id = _x; kind = _x_i1; }
-    method length_object : length_object -> length_object = o#unknown
-    method label : label -> label = o#string
-    method kind : kind -> kind = o#unknown
-    method jsint : jsint -> jsint = o#int32
-    method int_op : int_op -> int_op = o#unknown
-    method ident_info : ident_info -> ident_info = o#unknown
-    method ident : ident -> ident = o#unknown
-    method for_ident_expression :
-      for_ident_expression -> for_ident_expression = o#expression
-    method for_ident : for_ident -> for_ident = o#ident
-    method for_direction : for_direction -> for_direction = o#unknown
-    method finish_ident_expression :
-      finish_ident_expression -> finish_ident_expression = o#expression
-    method expression_desc : expression_desc -> expression_desc =
-      function
-      | Length (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#length_object _x_i1 in Length (_x, _x_i1)
-      | Char_of_int _x -> let _x = o#expression _x in Char_of_int _x
-      | Char_to_int _x -> let _x = o#expression _x in Char_to_int _x
-      | Is_null_or_undefined _x ->
-          let _x = o#expression _x in Is_null_or_undefined _x
-      | String_append (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in String_append (_x, _x_i1)
-      | Bool _x -> let _x = o#bool _x in Bool _x
-      | Typeof _x -> let _x = o#expression _x in Typeof _x
-      | Js_not _x -> let _x = o#expression _x in Js_not _x
-      | Seq (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in Seq (_x, _x_i1)
-      | Cond (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in
-          let _x_i2 = o#expression _x_i2 in Cond (_x, _x_i1, _x_i2)
-      | Bin (_x, _x_i1, _x_i2) ->
-          let _x = o#binop _x in
-          let _x_i1 = o#expression _x_i1 in
-          let _x_i2 = o#expression _x_i2 in Bin (_x, _x_i1, _x_i2)
-      | FlatCall (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in FlatCall (_x, _x_i1)
-      | Call (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#list (fun o -> o#expression) _x_i1 in
-          let _x_i2 = o#unknown _x_i2 in Call (_x, _x_i1, _x_i2)
-      | String_index (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in String_index (_x, _x_i1)
-      | Array_index (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in Array_index (_x, _x_i1)
-      | Static_index (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#string _x_i1 in
-          let _x_i2 = o#option (fun o -> o#int32) _x_i2
-          in Static_index (_x, _x_i1, _x_i2)
-      | New (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 =
-            o#option (fun o -> o#list (fun o -> o#expression)) _x_i1
-          in New (_x, _x_i1)
-      | Var _x -> let _x = o#vident _x in Var _x
-      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
-          let _x = o#bool _x in
-          let _x_i1 = o#list (fun o -> o#ident) _x_i1 in
-          let _x_i2 = o#block _x_i2 in
-          let _x_i3 = o#unknown _x_i3 in Fun (_x, _x_i1, _x_i2, _x_i3)
-      | Str (_x, _x_i1) ->
-          let _x = o#bool _x in let _x_i1 = o#string _x_i1 in Str (_x, _x_i1)
-      | Unicode _x -> let _x = o#string _x in Unicode _x
-      | Raw_js_code _x -> let _x = o#unknown _x in Raw_js_code _x
-      | Array (_x, _x_i1) ->
-          let _x = o#list (fun o -> o#expression) _x in
-          let _x_i1 = o#mutable_flag _x_i1 in Array (_x, _x_i1)
-      | Optional_block (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#bool _x_i1 in Optional_block (_x, _x_i1)
-      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
-          let _x = o#list (fun o -> o#expression) _x in
-          let _x_i1 = o#mutable_flag _x_i1 in
-          let _x_i2 = o#expression _x_i2 in
-          let _x_i3 = o#tag_info _x_i3
-          in Caml_block (_x, _x_i1, _x_i2, _x_i3)
-      | Caml_block_tag _x -> let _x = o#expression _x in Caml_block_tag _x
-      | Number _x -> let _x = o#number _x in Number _x
-      | Object _x -> let _x = o#property_map _x in Object _x
-      | Undefined -> Undefined
-      | Null -> Null
-    method expression : expression -> expression =
-      fun { expression_desc = _x; comment = _x_i1 } ->
-        let _x = o#expression_desc _x in
-        let _x_i1 = o#option (fun o -> o#string) _x_i1
-        in { expression_desc = _x; comment = _x_i1; }
-    method exports : exports -> exports = o#unknown
-    method exception_ident : exception_ident -> exception_ident = o#ident
-    method deps_program : deps_program -> deps_program =
-      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
-        let _x = o#program _x in
-        let _x_i1 = o#required_modules _x_i1 in
-        let _x_i2 = o#option (fun o -> o#string) _x_i2
-        in { program = _x; modules = _x_i1; side_effect = _x_i2; }
-    method case_clause :
-      'a 'a_out.
-        ('self_type -> 'a -> 'a_out) -> 'a case_clause -> 'a_out case_clause =
-      fun _f_a
-        {
-          switch_case = _x;
-          switch_body = _x_i1;
-          should_break = _x_i2;
-          comment = _x_i3
-        } ->
-        let _x = _f_a o _x in
-        let _x_i1 = o#block _x_i1 in
-        let _x_i2 = o#bool _x_i2 in
-        let _x_i3 = o#option (fun o -> o#string) _x_i3
-        in
-          {
-            switch_case = _x;
-            switch_body = _x_i1;
-            should_break = _x_i2;
-            comment = _x_i3;
-          }
-    method block : block -> block = (* true means break *)
+      (* true means break *)
       (* TODO: For efficency: block should not be a list, it should be able to 
    be concatenated in both ways 
  *)
@@ -108512,7 +108498,7 @@ let eval (arg : J.expression) (dispatches : (string * string) list ) : E.t =
       E.of_block
         [(S.string_switch arg
             (Ext_list.map dispatches (fun (i,r) ->
-                 {J.switch_case = i ;
+                 i, J.{
                   switch_body = [S.return_stmt (E.str r)];
                   should_break = false; (* FIXME: if true, still print break*)
                   comment = None;
@@ -108540,7 +108526,7 @@ let eval_as_event (arg : J.expression) (dispatches : (string * string) list opti
       
         (S.string_switch (E.poly_var_tag_access arg)
         (Ext_list.map dispatches (fun (i,r) ->
-              {J.switch_case = i ;
+              i, J.{
                switch_body = [S.return_stmt (E.str r)];
                should_break = false; (* FIXME: if true, still print break*)
                comment = None;
@@ -108572,7 +108558,7 @@ let eval_as_int (arg : J.expression) (dispatches : (string * int) list ) : E.t
     E.of_block
       [(S.string_switch arg
       (Ext_list.map dispatches (fun (i,r) ->
-              {J.switch_case = i ;
+              i, J.{
                switch_body = [S.return_stmt (E.int (Int32.of_int  r))];
                should_break = false; (* FIXME: if true, still print break*)
                comment = None;
@@ -113747,7 +113733,7 @@ and compile_general_cases
   Lam_compile_context.t ->
   (?default:J.block ->
    ?declaration:Lam_compat.let_kind * Ident.t  ->
-   _ -> 'a J.case_clause list ->  J.statement) ->
+   _ -> ('a * J.case_clause) list ->  J.statement) ->
   _ ->
   ('a * Lam.t) list -> default_case -> J.block
   = fun
@@ -113758,7 +113744,7 @@ and compile_general_cases
   (switch :
   ?default:J.block ->
    ?declaration:Lam_compat.let_kind * Ident.t  ->
-   _ -> _ J.case_clause list ->  J.statement
+   _ -> (_ * J.case_clause) list ->  J.statement
    )
    (switch_exp : J.expression)
    (cases : (_ * Lam.t) list)
@@ -113828,13 +113814,13 @@ and compile_general_cases
                               should_break
                             else
                               should_break && Lam_exit_code.has_exit lam in
-                        {J.switch_case ;
+                          switch_case , J.{
                             switch_body;
                             should_break;
                             comment = make_comment switch_case;
                         }
                       else
-                        { switch_case; switch_body = []; should_break = false; comment = make_comment switch_case; }
+                      switch_case, {switch_body = []; should_break = false; comment = make_comment switch_case; }
                     )                   
               
               (* TODO: we should also group default *)
diff --git a/lib/4.06.1/whole_compiler.ml b/lib/4.06.1/whole_compiler.ml
index 8023a8efc7..a13379040a 100644
--- a/lib/4.06.1/whole_compiler.ml
+++ b/lib/4.06.1/whole_compiler.ml
@@ -370301,8 +370301,8 @@ and statement_desc =
     {[ goto : label option ; ]}
   *)
 
-  | Int_switch of expression * int case_clause list * block option 
-  | String_switch of expression * string case_clause list * block option 
+  | Int_switch of expression * int_clause list * block option 
+  | String_switch of expression * string_clause list * block option 
   | Throw of expression
   | Try of block * (exception_ident * block) option * block option
   | Debugger
@@ -370325,9 +370325,9 @@ and variable_declaration = {
   property : property;
   ident_info : ident_info;
 }
-
-and 'a case_clause = { 
-  switch_case : 'a ; 
+and string_clause = string * case_clause
+and int_clause =  int * case_clause
+and case_clause = {   
   switch_body : block ;
   should_break :  bool ;  (* true means break *)
   comment : string option ;
@@ -376424,6 +376424,9 @@ class virtual fold =
         let o = o#option (fun o -> o#expression) _x_i1 in
         let o = o#property _x_i2 in let o = o#ident_info _x_i3 in o
     method tag_info : tag_info -> 'self_type = o#unknown
+    method string_clause : string_clause -> 'self_type =
+      fun (_x, _x_i1) ->
+        let o = o#string _x in let o = o#case_clause _x_i1 in o
     method statement_desc : statement_desc -> 'self_type =
       function
       | Block _x -> let o = o#block _x in o
@@ -376447,10 +376450,28 @@ class virtual fold =
       | Return _x -> let o = o#expression _x in o
       | Int_switch (_x, _x_i1, _x_i2) ->
           let o = o#expression _x in
+          let o = o#list (fun o -> o#int_clause) _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | String_switch (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#list (fun o -> o#string_clause) _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | Throw _x -> let o = o#expression _x in o
+      | Try (_x, _x_i1, _x_i2) ->
+          let o = o#block _x in
           let o =
-            o#list
-              (fun o ->
-                 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+            o#option
+              (fun o (_x, _x_i1) ->
+                 let o = o#exception_ident _x in let o = o#block _x_i1 in o)
+              _x_i1 in
+          let o = o#option (fun o -> o#block) _x_i2 in o
+      | Debugger -> o
+    method statement : statement -> 'self_type =
+      fun { statement_desc = _x; comment = _x_i1 } ->
+        let o = o#statement_desc _x in
+        let o = o#option (fun o -> o#string) _x_i1 in o
+    method required_modules : required_modules -> 'self_type =
+      (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
  * 
  * 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
@@ -376473,7 +376494,7 @@ class virtual fold =
  * 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. *)
-                 (* Javascript IR
+      (* Javascript IR
   
     It's a subset of Javascript AST specialized for OCaml lambda backend
 
@@ -376481,15 +376502,18 @@ class virtual fold =
     convention and [Block] is just a sequence of statements, which means it does 
     not introduce new scope
 *)
-                 (* TODO: it seems that camlp4of supports very limited structures
+      (* TODO: it seems that camlp4of supports very limited structures
    it does not even support attributes like `[@@@warning "-30"]
    we should get rid of such dependency ASAP
 *)
-                 (** object literal, if key is ident, in this case, it might be renamed by 
+      o#list (fun o -> o#module_id)
+    method property_name : property_name -> 'self_type = o#unknown
+    method property_map : property_map -> 'self_type =
+      (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-                 (* Since camldot is only available for toplevel module accessors,
+      (* Since camldot is only available for toplevel module accessors,
        we don't need print  `A.length$2`
        just print `A.length` - it's guarateed to be unique
        
@@ -376504,7 +376528,74 @@ class virtual fold =
          Qualified (_, Runtime, Some "caml_int_compare")         
        ]}       
      *)
-                 (** where we use a trick [== null ] *) (* js true/false*)
+      o#list
+        (fun o (_x, _x_i1) ->
+           let o = o#property_name _x in let o = o#expression _x_i1 in o)
+    method property : property -> 'self_type = o#unknown
+    method program : program -> 'self_type =
+      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
+        let o = o#block _x in
+        let o = o#exports _x_i1 in let o = o#unknown _x_i2 in o
+    method number : number -> 'self_type = o#unknown
+    method mutable_flag : mutable_flag -> 'self_type = o#unknown
+    method module_id : module_id -> 'self_type =
+      fun { id = _x; kind = _x_i1 } ->
+        let o = o#ident _x in let o = o#unknown _x_i1 in o
+    method length_object : length_object -> 'self_type = o#unknown
+    method label : label -> 'self_type = o#string
+    method kind : kind -> 'self_type = o#unknown
+    method jsint : jsint -> 'self_type = o#int32
+    method int_op : int_op -> 'self_type = o#unknown
+    method int_clause : int_clause -> 'self_type =
+      fun (_x, _x_i1) -> let o = o#int _x in let o = o#case_clause _x_i1 in o
+    method ident_info : ident_info -> 'self_type = o#unknown
+    method ident : ident -> 'self_type = o#unknown
+    method for_ident_expression : for_ident_expression -> 'self_type =
+      o#expression
+    method for_ident : for_ident -> 'self_type = o#ident
+    method for_direction : for_direction -> 'self_type = o#unknown
+    method finish_ident_expression : finish_ident_expression -> 'self_type =
+      o#expression
+    method expression_desc : expression_desc -> 'self_type =
+      function
+      | Length (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#length_object _x_i1 in o
+      | Char_of_int _x -> let o = o#expression _x in o
+      | Char_to_int _x -> let o = o#expression _x in o
+      | Is_null_or_undefined _x -> let o = o#expression _x in o
+      | String_append (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Bool _x -> let o = o#bool _x in o
+      | Typeof _x -> let o = o#expression _x in o
+      | Js_not _x -> let o = o#expression _x in o
+      | Seq (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Cond (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
+      | Bin (_x, _x_i1, _x_i2) ->
+          let o = o#binop _x in
+          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
+      | FlatCall (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Call (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#list (fun o -> o#expression) _x_i1 in
+          let o = o#unknown _x_i2 in o
+      | String_index (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Array_index (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#expression _x_i1 in o
+      | Static_index (_x, _x_i1, _x_i2) ->
+          let o = o#expression _x in
+          let o = o#string _x_i1 in
+          let o = o#option (fun o -> o#int32) _x_i2 in o
+      | New (_x, _x_i1) ->
+          let o = o#expression _x in
+          let o =
+            o#option
+              (fun o -> (** where we use a trick [== null ] *)
+                 (* js true/false*)
                  (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence 
      [typeof] is an operator     
   *)
@@ -376539,11 +376630,52 @@ class virtual fold =
           All exported declarations have to be OCaml identifiers
        2. Javascript dot (need to be preserved/or using quote)
      *)
-                 (* TODO: option remove *)
-                 (* The first parameter by default is false, 
+                 o#list (fun o -> o#expression))
+              _x_i1
+          in o
+      | Var _x -> let o = o#vident _x in o
+      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
+          let o = o#bool _x in
+          let o = o#list (fun o -> o#ident) _x_i1 in
+          let o = o#block _x_i2 in let o = o#unknown _x_i3 in o
+      | Str (_x, _x_i1) -> let o = o#bool _x in let o = o#string _x_i1 in o
+      | Unicode _x -> let o = o#string _x in o
+      | Raw_js_code _x -> let o = o#unknown _x in o
+      | Array (_x, _x_i1) ->
+          let o = o#list (fun o -> o#expression) _x in
+          let o = o#mutable_flag _x_i1 in o
+      | Optional_block (_x, _x_i1) ->
+          let o = o#expression _x in let o = o#bool _x_i1 in o
+      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
+          let o = o#list (fun o -> o#expression) _x in
+          let o = o#mutable_flag _x_i1 in
+          let o = o#expression _x_i2 in let o = o#tag_info _x_i3 in o
+      | Caml_block_tag _x -> let o = o#expression _x in o
+      | Number _x -> let o = o#number _x in o
+      | Object _x -> let o = o#property_map _x in o
+      | Undefined -> o
+      | Null -> o
+    method expression : expression -> 'self_type =
+      fun { expression_desc = _x; comment = _x_i1 } ->
+        let o = o#expression_desc _x in
+        let o = o#option (fun o -> o#string) _x_i1 in o
+    method exports : exports -> 'self_type = o#unknown
+    method exception_ident : exception_ident -> 'self_type = o#ident
+    method deps_program : deps_program -> 'self_type =
+      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
+        let o = o#program _x in
+        let o = o#required_modules _x_i1 in
+        let o = o#option (fun o -> o#string) _x_i2 in o
+    method case_clause : case_clause -> 'self_type =
+      fun { switch_body = _x; should_break = _x_i1; comment = _x_i2 } ->
+        let o = o#block _x in
+        let o = o#bool _x_i1 in
+        let o = o#option (fun o -> o#string) _x_i2 in o
+    method block : block -> 'self_type = (* TODO: option remove *)
+      (* The first parameter by default is false, 
      it will be true when it's a method
   *)
-                 (* A string is UTF-8 encoded, the string may contain
+      (* A string is UTF-8 encoded, the string may contain
        escape sequences.
        The first argument is used to mark it is non-pure, please
        don't optimize it, since it does have side effec, 
@@ -376551,13 +376683,13 @@ class virtual fold =
        which is better to leave it alone
        The last argument is passed from as `j` from `{j||j}`
      *)
-                 (* It is escaped string, print delimited by '"'*)
-                 (* literally raw JS code 
+      (* It is escaped string, print delimited by '"'*)
+      (* literally raw JS code 
   *) (* [true] means [identity] *)
-                 (* The third argument is [tag] , forth is [tag_info] *)
-                 (* | Caml_uninitialized_obj of expression * expression *)
-                 (* [tag] and [size] tailed  for [Obj.new_block] *)
-                 (* For setter, it still return the value of expression, 
+      (* The third argument is [tag] , forth is [tag_info] *)
+      (* | Caml_uninitialized_obj of expression * expression *)
+      (* [tag] and [size] tailed  for [Obj.new_block] *)
+      (* For setter, it still return the value of expression, 
      we can not use 
      {[
        type 'a access = Get | Set of 'a
@@ -376566,20 +376698,20 @@ class virtual fold =
      [Caml_block_tag] can return [undefined], 
      you have to use [E.tag] in a safe way     
   *)
-                 (* | Caml_block_set_tag of expression * expression *)
-                 (* | Caml_block_set_length of expression * expression *)
-                 (* It will just fetch tag, to make it safe, when creating it, 
+      (* | Caml_block_set_tag of expression * expression *)
+      (* | Caml_block_set_length of expression * expression *)
+      (* It will just fetch tag, to make it safe, when creating it, 
      we need apply "|0", we don't do it in the 
      last step since "|0" can potentially be optimized
   *)
-                 (* pure*) (* pure *)
-                 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
+      (* pure*) (* pure *)
+      (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
    block can be nested, specified in ES3 
  *)
-                 (* Delay some units like [primitive] into JS layer ,
+      (* Delay some units like [primitive] into JS layer ,
    benefit: better cross module inlining, and smaller IR size?
  *)
-                 (* 
+      (* 
   [closure] captured loop mutable values in the outer loop
 
   check if it contains loop mutable values, happens in nested loop
@@ -376605,7 +376737,7 @@ class virtual fold =
   contains a block side effect
   TODO: create such example
 *)
-                 (* Since in OCaml, 
+      (* Since in OCaml, 
    
   [for i = 0 to k end do done ]
   k is only evaluated once , to encode this invariant in JS IR,
@@ -376614,7 +376746,7 @@ class virtual fold =
   TODO: currently we guarantee that [bound] was only 
   excecuted once, should encode this in AST level
 *)
-                 (* Can be simplified to keep the semantics of OCaml
+      (* Can be simplified to keep the semantics of OCaml
    For (var i, e, ...){
      let  j = ... 
    }
@@ -376626,7 +376758,7 @@ class virtual fold =
      })(i)
    }
 *)
-                 (* Single return is good for ininling..
+      (* Single return is good for ininling..
    However, when you do tail-call optmization
    you loose the expression oriented semantics
    Block is useful for implementing goto
@@ -376636,12 +376768,12 @@ class virtual fold =
    }
    ]}
 *)
-                 (* Function declaration and Variable declaration  *)
-                 (* check if it contains loop mutable values, happens in nested loop *)
-                 (* only used when inline a fucntion *)
-                 (* Here we need track back a bit ?, move Return to Function ...
+      (* Function declaration and Variable declaration  *)
+      (* check if it contains loop mutable values, happens in nested loop *)
+      (* only used when inline a fucntion *)
+      (* Here we need track back a bit ?, move Return to Function ...
                               Then we can only have one Return, which is not good *)
-                 (* since in ocaml, it's expression oriented langauge, [return] in
+      (* since in ocaml, it's expression oriented langauge, [return] in
     general has no jumps, it only happens when we do 
     tailcall conversion, in that case there is a jump.
     However, currently  a single [break] is good to cover
@@ -376651,143 +376783,7 @@ class virtual fold =
     A more robust signature would be 
     {[ goto : label option ; ]}
   *)
-                 o#case_clause (fun o -> o#int))
-              _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | String_switch (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o =
-            o#list (fun o -> o#case_clause (fun o -> o#string)) _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | Throw _x -> let o = o#expression _x in o
-      | Try (_x, _x_i1, _x_i2) ->
-          let o = o#block _x in
-          let o =
-            o#option
-              (fun o (_x, _x_i1) ->
-                 let o = o#exception_ident _x in let o = o#block _x_i1 in o)
-              _x_i1 in
-          let o = o#option (fun o -> o#block) _x_i2 in o
-      | Debugger -> o
-    method statement : statement -> 'self_type =
-      fun { statement_desc = _x; comment = _x_i1 } ->
-        let o = o#statement_desc _x in
-        let o = o#option (fun o -> o#string) _x_i1 in o
-    method required_modules : required_modules -> 'self_type =
-      o#list (fun o -> o#module_id)
-    method property_name : property_name -> 'self_type = o#unknown
-    method property_map : property_map -> 'self_type =
-      o#list
-        (fun o (_x, _x_i1) ->
-           let o = o#property_name _x in let o = o#expression _x_i1 in o)
-    method property : property -> 'self_type = o#unknown
-    method program : program -> 'self_type =
-      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
-        let o = o#block _x in
-        let o = o#exports _x_i1 in let o = o#unknown _x_i2 in o
-    method number : number -> 'self_type = o#unknown
-    method mutable_flag : mutable_flag -> 'self_type = o#unknown
-    method module_id : module_id -> 'self_type =
-      fun { id = _x; kind = _x_i1 } ->
-        let o = o#ident _x in let o = o#unknown _x_i1 in o
-    method length_object : length_object -> 'self_type = o#unknown
-    method label : label -> 'self_type = o#string
-    method kind : kind -> 'self_type = o#unknown
-    method jsint : jsint -> 'self_type = o#int32
-    method int_op : int_op -> 'self_type = o#unknown
-    method ident_info : ident_info -> 'self_type = o#unknown
-    method ident : ident -> 'self_type = o#unknown
-    method for_ident_expression : for_ident_expression -> 'self_type =
-      o#expression
-    method for_ident : for_ident -> 'self_type = o#ident
-    method for_direction : for_direction -> 'self_type = o#unknown
-    method finish_ident_expression : finish_ident_expression -> 'self_type =
-      o#expression
-    method expression_desc : expression_desc -> 'self_type =
-      function
-      | Length (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#length_object _x_i1 in o
-      | Char_of_int _x -> let o = o#expression _x in o
-      | Char_to_int _x -> let o = o#expression _x in o
-      | Is_null_or_undefined _x -> let o = o#expression _x in o
-      | String_append (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Bool _x -> let o = o#bool _x in o
-      | Typeof _x -> let o = o#expression _x in o
-      | Js_not _x -> let o = o#expression _x in o
-      | Seq (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Cond (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
-      | Bin (_x, _x_i1, _x_i2) ->
-          let o = o#binop _x in
-          let o = o#expression _x_i1 in let o = o#expression _x_i2 in o
-      | FlatCall (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Call (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#list (fun o -> o#expression) _x_i1 in
-          let o = o#unknown _x_i2 in o
-      | String_index (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Array_index (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#expression _x_i1 in o
-      | Static_index (_x, _x_i1, _x_i2) ->
-          let o = o#expression _x in
-          let o = o#string _x_i1 in
-          let o = o#option (fun o -> o#int32) _x_i2 in o
-      | New (_x, _x_i1) ->
-          let o = o#expression _x in
-          let o = o#option (fun o -> o#list (fun o -> o#expression)) _x_i1
-          in o
-      | Var _x -> let o = o#vident _x in o
-      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
-          let o = o#bool _x in
-          let o = o#list (fun o -> o#ident) _x_i1 in
-          let o = o#block _x_i2 in let o = o#unknown _x_i3 in o
-      | Str (_x, _x_i1) -> let o = o#bool _x in let o = o#string _x_i1 in o
-      | Unicode _x -> let o = o#string _x in o
-      | Raw_js_code _x -> let o = o#unknown _x in o
-      | Array (_x, _x_i1) ->
-          let o = o#list (fun o -> o#expression) _x in
-          let o = o#mutable_flag _x_i1 in o
-      | Optional_block (_x, _x_i1) ->
-          let o = o#expression _x in let o = o#bool _x_i1 in o
-      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
-          let o = o#list (fun o -> o#expression) _x in
-          let o = o#mutable_flag _x_i1 in
-          let o = o#expression _x_i2 in let o = o#tag_info _x_i3 in o
-      | Caml_block_tag _x -> let o = o#expression _x in o
-      | Number _x -> let o = o#number _x in o
-      | Object _x -> let o = o#property_map _x in o
-      | Undefined -> o
-      | Null -> o
-    method expression : expression -> 'self_type =
-      fun { expression_desc = _x; comment = _x_i1 } ->
-        let o = o#expression_desc _x in
-        let o = o#option (fun o -> o#string) _x_i1 in o
-    method exports : exports -> 'self_type = o#unknown
-    method exception_ident : exception_ident -> 'self_type = o#ident
-    method deps_program : deps_program -> 'self_type =
-      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
-        let o = o#program _x in
-        let o = o#required_modules _x_i1 in
-        let o = o#option (fun o -> o#string) _x_i2 in o
-    method case_clause :
-      'a. ('self_type -> 'a -> 'self_type) -> 'a case_clause -> 'self_type =
-      fun _f_a
-        {
-          switch_case = _x;
-          switch_body = _x_i1;
-          should_break = _x_i2;
-          comment = _x_i3
-        } ->
-        let o = _f_a o _x in
-        let o = o#block _x_i1 in
-        let o = o#bool _x_i2 in
-        let o = o#option (fun o -> o#string) _x_i3 in o
-    method block : block -> 'self_type = (* true means break *)
+      (* true means break *)
       (* TODO: For efficency: block should not be a list, it should be able to 
    be concatenated in both ways 
  *)
@@ -380180,9 +380176,9 @@ and  pp_function ~is_method
     since it can be either [int] or [string]
 *)
 and pp_one_case_clause : 'a .
-  _ -> P.t -> (P.t -> 'a -> unit) -> 'a J.case_clause -> _
+  _ -> P.t -> (P.t -> 'a -> unit) -> ('a * J.case_clause) -> _
   = fun cxt f  pp_cond
-    ({switch_case; switch_body ; should_break; comment; } : _ J.case_clause) ->
+    (switch_case, ({switch_body ; should_break; comment; } :  J.case_clause)) ->
     let cxt =
       P.group f 1  (fun _ ->
           P.group f 1 (fun _ ->
@@ -380212,7 +380208,7 @@ and pp_one_case_clause : 'a .
     cxt
 
 and loop_case_clauses  :  'a . cxt ->
-  P.t -> (P.t -> 'a -> unit) -> 'a J.case_clause list -> cxt
+  P.t -> (P.t -> 'a -> unit) -> ('a * J.case_clause) list -> cxt
   = fun  cxt  f pp_cond cases ->
     Ext_list.fold_left cases cxt (fun acc x -> pp_one_case_clause acc f pp_cond x)              
 
@@ -382071,7 +382067,7 @@ val int_switch :
   ?declaration:Lam_compat.let_kind * Ident.t -> 
   ?default:J.block -> 
   J.expression -> 
-  int J.case_clause list -> 
+  (int * J.case_clause) list -> 
   t 
 
 val string_switch : 
@@ -382079,7 +382075,7 @@ val string_switch :
   ?declaration:Lam_compat.let_kind * Ident.t -> 
   ?default:J.block ->
   J.expression -> 
-  string J.case_clause list ->
+  (string * J.case_clause) list ->
   t
 
 (** Just declaration without initialization *)  
@@ -382289,13 +382285,13 @@ let int_switch
     ?(declaration : (J.property * Ident.t) option )
     ?(default : J.block option)
     (e : J.expression)  
-    (clauses : int J.case_clause list): t = 
+    (clauses : (int * J.case_clause) list): t = 
   match e.expression_desc with 
   | Number (Int {i; _}) -> 
     let continuation =  
       match Ext_list.find_opt clauses
-              (fun x ->
-                 if x.switch_case = Int32.to_int i then
+              (fun (switch_case,x) ->
+                 if switch_case = Int32.to_int i then
                    Some x.switch_body else None ) 
       with 
       | Some case -> case 
@@ -382328,12 +382324,12 @@ let string_switch
   ?(declaration : (J.property * Ident.t) option) 
   ?(default : J.block option)
   (e : J.expression)  
-  (clauses : string J.case_clause list): t= 
+  (clauses : (string * J.case_clause) list): t= 
   match e.expression_desc with 
   | Str (_,s) -> 
     let continuation = 
-      match Ext_list.find_opt clauses (fun  x ->
-                 if x.switch_case = s then 
+      match Ext_list.find_opt clauses (fun  (switch_case, x) ->
+                 if switch_case = s then 
                    Some x.switch_body
                  else None  
               ) with 
@@ -384224,6 +384220,10 @@ class virtual map =
           { ident = _x; value = _x_i1; property = _x_i2; ident_info = _x_i3;
           }
     method tag_info : tag_info -> tag_info = o#unknown
+    method string_clause : string_clause -> string_clause =
+      fun (_x, _x_i1) ->
+        let _x = o#string _x in
+        let _x_i1 = o#case_clause _x_i1 in (_x, _x_i1)
     method statement_desc : statement_desc -> statement_desc =
       function
       | Block _x -> let _x = o#block _x in Block _x
@@ -384251,13 +384251,36 @@ class virtual map =
       | Return _x -> let _x = o#expression _x in Return _x
       | Int_switch (_x, _x_i1, _x_i2) ->
           let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#int_clause) _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in Int_switch (_x, _x_i1, _x_i2)
+      | String_switch (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#string_clause) _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in String_switch (_x, _x_i1, _x_i2)
+      | Throw _x -> let _x = o#expression _x in Throw _x
+      | Try (_x, _x_i1, _x_i2) ->
+          let _x = o#block _x in
           let _x_i1 =
-            o#list
-              (fun o ->
-                 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
- * 
- * 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
+            o#option
+              (fun o (_x, _x_i1) ->
+                 let _x = o#exception_ident _x in
+                 let _x_i1 = o#block _x_i1 in (_x, _x_i1))
+              _x_i1 in
+          let _x_i2 = o#option (fun o -> o#block) _x_i2
+          in Try (_x, _x_i1, _x_i2)
+      | Debugger -> Debugger
+    method statement : statement -> statement =
+      fun { statement_desc = _x; comment = _x_i1 } ->
+        let _x = o#statement_desc _x in
+        let _x_i1 = o#option (fun o -> o#string) _x_i1
+        in { statement_desc = _x; comment = _x_i1; }
+    method required_modules : required_modules -> required_modules =
+      (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * 
+ * 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.
  *
@@ -384277,7 +384300,7 @@ class virtual map =
  * 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. *)
-                 (* Javascript IR
+      (* Javascript IR
   
     It's a subset of Javascript AST specialized for OCaml lambda backend
 
@@ -384285,15 +384308,18 @@ class virtual map =
     convention and [Block] is just a sequence of statements, which means it does 
     not introduce new scope
 *)
-                 (* TODO: it seems that camlp4of supports very limited structures
+      (* TODO: it seems that camlp4of supports very limited structures
    it does not even support attributes like `[@@@warning "-30"]
    we should get rid of such dependency ASAP
 *)
-                 (** object literal, if key is ident, in this case, it might be renamed by 
+      o#list (fun o -> o#module_id)
+    method property_name : property_name -> property_name = o#unknown
+    method property_map : property_map -> property_map =
+      (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-                 (* Since camldot is only available for toplevel module accessors,
+      (* Since camldot is only available for toplevel module accessors,
        we don't need print  `A.length$2`
        just print `A.length` - it's guarateed to be unique
        
@@ -384308,7 +384334,89 @@ class virtual map =
          Qualified (_, Runtime, Some "caml_int_compare")         
        ]}       
      *)
-                 (** where we use a trick [== null ] *) (* js true/false*)
+      o#list
+        (fun o (_x, _x_i1) ->
+           let _x = o#property_name _x in
+           let _x_i1 = o#expression _x_i1 in (_x, _x_i1))
+    method property : property -> property = o#unknown
+    method program : program -> program =
+      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
+        let _x = o#block _x in
+        let _x_i1 = o#exports _x_i1 in
+        let _x_i2 = o#unknown _x_i2
+        in { block = _x; exports = _x_i1; export_set = _x_i2; }
+    method number : number -> number = o#unknown
+    method mutable_flag : mutable_flag -> mutable_flag = o#unknown
+    method module_id : module_id -> module_id =
+      fun { id = _x; kind = _x_i1 } ->
+        let _x = o#ident _x in
+        let _x_i1 = o#unknown _x_i1 in { id = _x; kind = _x_i1; }
+    method length_object : length_object -> length_object = o#unknown
+    method label : label -> label = o#string
+    method kind : kind -> kind = o#unknown
+    method jsint : jsint -> jsint = o#int32
+    method int_op : int_op -> int_op = o#unknown
+    method int_clause : int_clause -> int_clause =
+      fun (_x, _x_i1) ->
+        let _x = o#int _x in let _x_i1 = o#case_clause _x_i1 in (_x, _x_i1)
+    method ident_info : ident_info -> ident_info = o#unknown
+    method ident : ident -> ident = o#unknown
+    method for_ident_expression :
+      for_ident_expression -> for_ident_expression = o#expression
+    method for_ident : for_ident -> for_ident = o#ident
+    method for_direction : for_direction -> for_direction = o#unknown
+    method finish_ident_expression :
+      finish_ident_expression -> finish_ident_expression = o#expression
+    method expression_desc : expression_desc -> expression_desc =
+      function
+      | Length (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#length_object _x_i1 in Length (_x, _x_i1)
+      | Char_of_int _x -> let _x = o#expression _x in Char_of_int _x
+      | Char_to_int _x -> let _x = o#expression _x in Char_to_int _x
+      | Is_null_or_undefined _x ->
+          let _x = o#expression _x in Is_null_or_undefined _x
+      | String_append (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in String_append (_x, _x_i1)
+      | Bool _x -> let _x = o#bool _x in Bool _x
+      | Typeof _x -> let _x = o#expression _x in Typeof _x
+      | Js_not _x -> let _x = o#expression _x in Js_not _x
+      | Seq (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in Seq (_x, _x_i1)
+      | Cond (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in
+          let _x_i2 = o#expression _x_i2 in Cond (_x, _x_i1, _x_i2)
+      | Bin (_x, _x_i1, _x_i2) ->
+          let _x = o#binop _x in
+          let _x_i1 = o#expression _x_i1 in
+          let _x_i2 = o#expression _x_i2 in Bin (_x, _x_i1, _x_i2)
+      | FlatCall (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in FlatCall (_x, _x_i1)
+      | Call (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#list (fun o -> o#expression) _x_i1 in
+          let _x_i2 = o#unknown _x_i2 in Call (_x, _x_i1, _x_i2)
+      | String_index (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in String_index (_x, _x_i1)
+      | Array_index (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#expression _x_i1 in Array_index (_x, _x_i1)
+      | Static_index (_x, _x_i1, _x_i2) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#string _x_i1 in
+          let _x_i2 = o#option (fun o -> o#int32) _x_i2
+          in Static_index (_x, _x_i1, _x_i2)
+      | New (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 =
+            o#option
+              (fun o -> (** where we use a trick [== null ] *)
+                 (* js true/false*)
                  (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence 
      [typeof] is an operator     
   *)
@@ -384343,11 +384451,60 @@ class virtual map =
           All exported declarations have to be OCaml identifiers
        2. Javascript dot (need to be preserved/or using quote)
      *)
-                 (* TODO: option remove *)
-                 (* The first parameter by default is false, 
+                 o#list (fun o -> o#expression))
+              _x_i1
+          in New (_x, _x_i1)
+      | Var _x -> let _x = o#vident _x in Var _x
+      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
+          let _x = o#bool _x in
+          let _x_i1 = o#list (fun o -> o#ident) _x_i1 in
+          let _x_i2 = o#block _x_i2 in
+          let _x_i3 = o#unknown _x_i3 in Fun (_x, _x_i1, _x_i2, _x_i3)
+      | Str (_x, _x_i1) ->
+          let _x = o#bool _x in let _x_i1 = o#string _x_i1 in Str (_x, _x_i1)
+      | Unicode _x -> let _x = o#string _x in Unicode _x
+      | Raw_js_code _x -> let _x = o#unknown _x in Raw_js_code _x
+      | Array (_x, _x_i1) ->
+          let _x = o#list (fun o -> o#expression) _x in
+          let _x_i1 = o#mutable_flag _x_i1 in Array (_x, _x_i1)
+      | Optional_block (_x, _x_i1) ->
+          let _x = o#expression _x in
+          let _x_i1 = o#bool _x_i1 in Optional_block (_x, _x_i1)
+      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
+          let _x = o#list (fun o -> o#expression) _x in
+          let _x_i1 = o#mutable_flag _x_i1 in
+          let _x_i2 = o#expression _x_i2 in
+          let _x_i3 = o#tag_info _x_i3
+          in Caml_block (_x, _x_i1, _x_i2, _x_i3)
+      | Caml_block_tag _x -> let _x = o#expression _x in Caml_block_tag _x
+      | Number _x -> let _x = o#number _x in Number _x
+      | Object _x -> let _x = o#property_map _x in Object _x
+      | Undefined -> Undefined
+      | Null -> Null
+    method expression : expression -> expression =
+      fun { expression_desc = _x; comment = _x_i1 } ->
+        let _x = o#expression_desc _x in
+        let _x_i1 = o#option (fun o -> o#string) _x_i1
+        in { expression_desc = _x; comment = _x_i1; }
+    method exports : exports -> exports = o#unknown
+    method exception_ident : exception_ident -> exception_ident = o#ident
+    method deps_program : deps_program -> deps_program =
+      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
+        let _x = o#program _x in
+        let _x_i1 = o#required_modules _x_i1 in
+        let _x_i2 = o#option (fun o -> o#string) _x_i2
+        in { program = _x; modules = _x_i1; side_effect = _x_i2; }
+    method case_clause : case_clause -> case_clause =
+      fun { switch_body = _x; should_break = _x_i1; comment = _x_i2 } ->
+        let _x = o#block _x in
+        let _x_i1 = o#bool _x_i1 in
+        let _x_i2 = o#option (fun o -> o#string) _x_i2
+        in { switch_body = _x; should_break = _x_i1; comment = _x_i2; }
+    method block : block -> block = (* TODO: option remove *)
+      (* The first parameter by default is false, 
      it will be true when it's a method
   *)
-                 (* A string is UTF-8 encoded, the string may contain
+      (* A string is UTF-8 encoded, the string may contain
        escape sequences.
        The first argument is used to mark it is non-pure, please
        don't optimize it, since it does have side effec, 
@@ -384355,13 +384512,13 @@ class virtual map =
        which is better to leave it alone
        The last argument is passed from as `j` from `{j||j}`
      *)
-                 (* It is escaped string, print delimited by '"'*)
-                 (* literally raw JS code 
+      (* It is escaped string, print delimited by '"'*)
+      (* literally raw JS code 
   *) (* [true] means [identity] *)
-                 (* The third argument is [tag] , forth is [tag_info] *)
-                 (* | Caml_uninitialized_obj of expression * expression *)
-                 (* [tag] and [size] tailed  for [Obj.new_block] *)
-                 (* For setter, it still return the value of expression, 
+      (* The third argument is [tag] , forth is [tag_info] *)
+      (* | Caml_uninitialized_obj of expression * expression *)
+      (* [tag] and [size] tailed  for [Obj.new_block] *)
+      (* For setter, it still return the value of expression, 
      we can not use 
      {[
        type 'a access = Get | Set of 'a
@@ -384370,20 +384527,20 @@ class virtual map =
      [Caml_block_tag] can return [undefined], 
      you have to use [E.tag] in a safe way     
   *)
-                 (* | Caml_block_set_tag of expression * expression *)
-                 (* | Caml_block_set_length of expression * expression *)
-                 (* It will just fetch tag, to make it safe, when creating it, 
+      (* | Caml_block_set_tag of expression * expression *)
+      (* | Caml_block_set_length of expression * expression *)
+      (* It will just fetch tag, to make it safe, when creating it, 
      we need apply "|0", we don't do it in the 
      last step since "|0" can potentially be optimized
   *)
-                 (* pure*) (* pure *)
-                 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
+      (* pure*) (* pure *)
+      (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
    block can be nested, specified in ES3 
  *)
-                 (* Delay some units like [primitive] into JS layer ,
+      (* Delay some units like [primitive] into JS layer ,
    benefit: better cross module inlining, and smaller IR size?
  *)
-                 (* 
+      (* 
   [closure] captured loop mutable values in the outer loop
 
   check if it contains loop mutable values, happens in nested loop
@@ -384409,7 +384566,7 @@ class virtual map =
   contains a block side effect
   TODO: create such example
 *)
-                 (* Since in OCaml, 
+      (* Since in OCaml, 
    
   [for i = 0 to k end do done ]
   k is only evaluated once , to encode this invariant in JS IR,
@@ -384418,7 +384575,7 @@ class virtual map =
   TODO: currently we guarantee that [bound] was only 
   excecuted once, should encode this in AST level
 *)
-                 (* Can be simplified to keep the semantics of OCaml
+      (* Can be simplified to keep the semantics of OCaml
    For (var i, e, ...){
      let  j = ... 
    }
@@ -384430,7 +384587,7 @@ class virtual map =
      })(i)
    }
 *)
-                 (* Single return is good for ininling..
+      (* Single return is good for ininling..
    However, when you do tail-call optmization
    you loose the expression oriented semantics
    Block is useful for implementing goto
@@ -384440,12 +384597,12 @@ class virtual map =
    }
    ]}
 *)
-                 (* Function declaration and Variable declaration  *)
-                 (* check if it contains loop mutable values, happens in nested loop *)
-                 (* only used when inline a fucntion *)
-                 (* Here we need track back a bit ?, move Return to Function ...
+      (* Function declaration and Variable declaration  *)
+      (* check if it contains loop mutable values, happens in nested loop *)
+      (* only used when inline a fucntion *)
+      (* Here we need track back a bit ?, move Return to Function ...
                               Then we can only have one Return, which is not good *)
-                 (* since in ocaml, it's expression oriented langauge, [return] in
+      (* since in ocaml, it's expression oriented langauge, [return] in
     general has no jumps, it only happens when we do 
     tailcall conversion, in that case there is a jump.
     However, currently  a single [break] is good to cover
@@ -384455,178 +384612,7 @@ class virtual map =
     A more robust signature would be 
     {[ goto : label option ; ]}
   *)
-                 o#case_clause (fun o -> o#int))
-              _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in Int_switch (_x, _x_i1, _x_i2)
-      | String_switch (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 =
-            o#list (fun o -> o#case_clause (fun o -> o#string)) _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in String_switch (_x, _x_i1, _x_i2)
-      | Throw _x -> let _x = o#expression _x in Throw _x
-      | Try (_x, _x_i1, _x_i2) ->
-          let _x = o#block _x in
-          let _x_i1 =
-            o#option
-              (fun o (_x, _x_i1) ->
-                 let _x = o#exception_ident _x in
-                 let _x_i1 = o#block _x_i1 in (_x, _x_i1))
-              _x_i1 in
-          let _x_i2 = o#option (fun o -> o#block) _x_i2
-          in Try (_x, _x_i1, _x_i2)
-      | Debugger -> Debugger
-    method statement : statement -> statement =
-      fun { statement_desc = _x; comment = _x_i1 } ->
-        let _x = o#statement_desc _x in
-        let _x_i1 = o#option (fun o -> o#string) _x_i1
-        in { statement_desc = _x; comment = _x_i1; }
-    method required_modules : required_modules -> required_modules =
-      o#list (fun o -> o#module_id)
-    method property_name : property_name -> property_name = o#unknown
-    method property_map : property_map -> property_map =
-      o#list
-        (fun o (_x, _x_i1) ->
-           let _x = o#property_name _x in
-           let _x_i1 = o#expression _x_i1 in (_x, _x_i1))
-    method property : property -> property = o#unknown
-    method program : program -> program =
-      fun { block = _x; exports = _x_i1; export_set = _x_i2 } ->
-        let _x = o#block _x in
-        let _x_i1 = o#exports _x_i1 in
-        let _x_i2 = o#unknown _x_i2
-        in { block = _x; exports = _x_i1; export_set = _x_i2; }
-    method number : number -> number = o#unknown
-    method mutable_flag : mutable_flag -> mutable_flag = o#unknown
-    method module_id : module_id -> module_id =
-      fun { id = _x; kind = _x_i1 } ->
-        let _x = o#ident _x in
-        let _x_i1 = o#unknown _x_i1 in { id = _x; kind = _x_i1; }
-    method length_object : length_object -> length_object = o#unknown
-    method label : label -> label = o#string
-    method kind : kind -> kind = o#unknown
-    method jsint : jsint -> jsint = o#int32
-    method int_op : int_op -> int_op = o#unknown
-    method ident_info : ident_info -> ident_info = o#unknown
-    method ident : ident -> ident = o#unknown
-    method for_ident_expression :
-      for_ident_expression -> for_ident_expression = o#expression
-    method for_ident : for_ident -> for_ident = o#ident
-    method for_direction : for_direction -> for_direction = o#unknown
-    method finish_ident_expression :
-      finish_ident_expression -> finish_ident_expression = o#expression
-    method expression_desc : expression_desc -> expression_desc =
-      function
-      | Length (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#length_object _x_i1 in Length (_x, _x_i1)
-      | Char_of_int _x -> let _x = o#expression _x in Char_of_int _x
-      | Char_to_int _x -> let _x = o#expression _x in Char_to_int _x
-      | Is_null_or_undefined _x ->
-          let _x = o#expression _x in Is_null_or_undefined _x
-      | String_append (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in String_append (_x, _x_i1)
-      | Bool _x -> let _x = o#bool _x in Bool _x
-      | Typeof _x -> let _x = o#expression _x in Typeof _x
-      | Js_not _x -> let _x = o#expression _x in Js_not _x
-      | Seq (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in Seq (_x, _x_i1)
-      | Cond (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in
-          let _x_i2 = o#expression _x_i2 in Cond (_x, _x_i1, _x_i2)
-      | Bin (_x, _x_i1, _x_i2) ->
-          let _x = o#binop _x in
-          let _x_i1 = o#expression _x_i1 in
-          let _x_i2 = o#expression _x_i2 in Bin (_x, _x_i1, _x_i2)
-      | FlatCall (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in FlatCall (_x, _x_i1)
-      | Call (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#list (fun o -> o#expression) _x_i1 in
-          let _x_i2 = o#unknown _x_i2 in Call (_x, _x_i1, _x_i2)
-      | String_index (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in String_index (_x, _x_i1)
-      | Array_index (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#expression _x_i1 in Array_index (_x, _x_i1)
-      | Static_index (_x, _x_i1, _x_i2) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#string _x_i1 in
-          let _x_i2 = o#option (fun o -> o#int32) _x_i2
-          in Static_index (_x, _x_i1, _x_i2)
-      | New (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 =
-            o#option (fun o -> o#list (fun o -> o#expression)) _x_i1
-          in New (_x, _x_i1)
-      | Var _x -> let _x = o#vident _x in Var _x
-      | Fun (_x, _x_i1, _x_i2, _x_i3) ->
-          let _x = o#bool _x in
-          let _x_i1 = o#list (fun o -> o#ident) _x_i1 in
-          let _x_i2 = o#block _x_i2 in
-          let _x_i3 = o#unknown _x_i3 in Fun (_x, _x_i1, _x_i2, _x_i3)
-      | Str (_x, _x_i1) ->
-          let _x = o#bool _x in let _x_i1 = o#string _x_i1 in Str (_x, _x_i1)
-      | Unicode _x -> let _x = o#string _x in Unicode _x
-      | Raw_js_code _x -> let _x = o#unknown _x in Raw_js_code _x
-      | Array (_x, _x_i1) ->
-          let _x = o#list (fun o -> o#expression) _x in
-          let _x_i1 = o#mutable_flag _x_i1 in Array (_x, _x_i1)
-      | Optional_block (_x, _x_i1) ->
-          let _x = o#expression _x in
-          let _x_i1 = o#bool _x_i1 in Optional_block (_x, _x_i1)
-      | Caml_block (_x, _x_i1, _x_i2, _x_i3) ->
-          let _x = o#list (fun o -> o#expression) _x in
-          let _x_i1 = o#mutable_flag _x_i1 in
-          let _x_i2 = o#expression _x_i2 in
-          let _x_i3 = o#tag_info _x_i3
-          in Caml_block (_x, _x_i1, _x_i2, _x_i3)
-      | Caml_block_tag _x -> let _x = o#expression _x in Caml_block_tag _x
-      | Number _x -> let _x = o#number _x in Number _x
-      | Object _x -> let _x = o#property_map _x in Object _x
-      | Undefined -> Undefined
-      | Null -> Null
-    method expression : expression -> expression =
-      fun { expression_desc = _x; comment = _x_i1 } ->
-        let _x = o#expression_desc _x in
-        let _x_i1 = o#option (fun o -> o#string) _x_i1
-        in { expression_desc = _x; comment = _x_i1; }
-    method exports : exports -> exports = o#unknown
-    method exception_ident : exception_ident -> exception_ident = o#ident
-    method deps_program : deps_program -> deps_program =
-      fun { program = _x; modules = _x_i1; side_effect = _x_i2 } ->
-        let _x = o#program _x in
-        let _x_i1 = o#required_modules _x_i1 in
-        let _x_i2 = o#option (fun o -> o#string) _x_i2
-        in { program = _x; modules = _x_i1; side_effect = _x_i2; }
-    method case_clause :
-      'a 'a_out.
-        ('self_type -> 'a -> 'a_out) -> 'a case_clause -> 'a_out case_clause =
-      fun _f_a
-        {
-          switch_case = _x;
-          switch_body = _x_i1;
-          should_break = _x_i2;
-          comment = _x_i3
-        } ->
-        let _x = _f_a o _x in
-        let _x_i1 = o#block _x_i1 in
-        let _x_i2 = o#bool _x_i2 in
-        let _x_i3 = o#option (fun o -> o#string) _x_i3
-        in
-          {
-            switch_case = _x;
-            switch_body = _x_i1;
-            should_break = _x_i2;
-            comment = _x_i3;
-          }
-    method block : block -> block = (* true means break *)
+      (* true means break *)
       (* TODO: For efficency: block should not be a list, it should be able to 
    be concatenated in both ways 
  *)
@@ -390994,7 +390980,7 @@ let eval (arg : J.expression) (dispatches : (string * string) list ) : E.t =
       E.of_block
         [(S.string_switch arg
             (Ext_list.map dispatches (fun (i,r) ->
-                 {J.switch_case = i ;
+                 i, J.{
                   switch_body = [S.return_stmt (E.str r)];
                   should_break = false; (* FIXME: if true, still print break*)
                   comment = None;
@@ -391022,7 +391008,7 @@ let eval_as_event (arg : J.expression) (dispatches : (string * string) list opti
       
         (S.string_switch (E.poly_var_tag_access arg)
         (Ext_list.map dispatches (fun (i,r) ->
-              {J.switch_case = i ;
+              i, J.{
                switch_body = [S.return_stmt (E.str r)];
                should_break = false; (* FIXME: if true, still print break*)
                comment = None;
@@ -391054,7 +391040,7 @@ let eval_as_int (arg : J.expression) (dispatches : (string * int) list ) : E.t
     E.of_block
       [(S.string_switch arg
       (Ext_list.map dispatches (fun (i,r) ->
-              {J.switch_case = i ;
+              i, J.{
                switch_body = [S.return_stmt (E.int (Int32.of_int  r))];
                should_break = false; (* FIXME: if true, still print break*)
                comment = None;
@@ -396141,7 +396127,7 @@ and compile_general_cases
   Lam_compile_context.t ->
   (?default:J.block ->
    ?declaration:Lam_compat.let_kind * Ident.t  ->
-   _ -> 'a J.case_clause list ->  J.statement) ->
+   _ -> ('a * J.case_clause) list ->  J.statement) ->
   _ ->
   ('a * Lam.t) list -> default_case -> J.block
   = fun
@@ -396152,7 +396138,7 @@ and compile_general_cases
   (switch :
   ?default:J.block ->
    ?declaration:Lam_compat.let_kind * Ident.t  ->
-   _ -> _ J.case_clause list ->  J.statement
+   _ -> (_ * J.case_clause) list ->  J.statement
    )
    (switch_exp : J.expression)
    (cases : (_ * Lam.t) list)
@@ -396222,13 +396208,13 @@ and compile_general_cases
                               should_break
                             else
                               should_break && Lam_exit_code.has_exit lam in
-                        {J.switch_case ;
+                          switch_case , J.{
                             switch_body;
                             should_break;
                             comment = make_comment switch_case;
                         }
                       else
-                        { switch_case; switch_body = []; should_break = false; comment = make_comment switch_case; }
+                      switch_case, {switch_body = []; should_break = false; comment = make_comment switch_case; }
                     )                   
               
               (* TODO: we should also group default *)