diff --git a/docs/docson/build-schema.json b/docs/docson/build-schema.json
index e16071d685..21635750d7 100644
--- a/docs/docson/build-schema.json
+++ b/docs/docson/build-schema.json
@@ -481,6 +481,10 @@
             "type": "boolean",
             "description": "(Experimental) whether to use the OCaml standard library. Default: true"
         },
+        "external-stdlib" : {
+            "type" : "string",
+            "description": "Use the external stdlib library instead of the one shipped with the compiler package"
+        },
         "bs-external-includes": {
             "type": "array",
             "items": {
diff --git a/jscomp/bsb/bsb_build_schemas.ml b/jscomp/bsb/bsb_build_schemas.ml
index 90cdeb56bf..a5a4bf5e1e 100644
--- a/jscomp/bsb/bsb_build_schemas.ml
+++ b/jscomp/bsb/bsb_build_schemas.ml
@@ -65,6 +65,7 @@ let export_none = "none"
 
 
 let use_stdlib = "use-stdlib"
+let external_stdlib = "external-stdlib"
 let reason = "reason"
 let react_jsx = "react-jsx"
 
diff --git a/jscomp/bsb/bsb_config_parse.ml b/jscomp/bsb/bsb_config_parse.ml
index 69fcdb0523..dd4f185358 100644
--- a/jscomp/bsb/bsb_config_parse.ml
+++ b/jscomp/bsb/bsb_config_parse.ml
@@ -90,48 +90,26 @@ let extract_package_name_and_namespace
     - the running bsb and vendoring bsb is the same
     - the running bsb need delete stale build artifacts
       (kinda check npm upgrade)
-*)
-let check_version_exit (map : json_map) stdlib_path =   
-  match Map_string.find_exn map Bsb_build_schemas.version with 
-  | Str {str } -> 
-    if str <> Bs_version.version then 
-      begin
-        Format.fprintf Format.err_formatter
-          "@{<error>bs-platform version mismatch@} Running bsb @{<info>%s@} (%s) vs vendored @{<info>%s@} (%s)@."
-          Bs_version.version
-          (Filename.dirname (Filename.dirname Sys.executable_name))
-          str
-          stdlib_path 
-        ;
-        exit 2
-      end
-  | _ -> assert false
-
-let check_stdlib (map : json_map) cwd (*built_in_package*) =  
+
+      Note if the setup is correct: 
+      the running compiler and node_modules/bs-platform
+      should be the same version, 
+      The exact check is that the running compiler should have a 
+      compatible runtime version installed, the location of the
+      compiler is actually not relevant.
+      We disable the check temporarily
+      e.g,
+      ```
+      bsc -runtime runtime_dir@version
+      ```
+*)  
+let check_stdlib (map : json_map) (*built_in_package*) : bool =  
   match map.?( Bsb_build_schemas.use_stdlib) with      
-  | Some (False _) -> None    
+  | Some (False _) -> false
   | None 
-  | Some _ ->
-    begin
-      let current_package : Bsb_pkg_types.t = Global !Bs_version.package_name in  
-      if Sys.getenv_opt "RES_SKIP_STDLIB_CHECK" = None then begin 
-        let stdlib_path = 
-          Bsb_pkg.resolve_bs_package ~cwd current_package in 
-        let json_spec = 
-          Ext_json_parse.parse_json_from_file
-            (* No exn raised: stdlib  has package.json *)
-            (Filename.concat stdlib_path Literals.package_json) in 
-        match json_spec with 
-        | Obj {map}  -> 
-          check_version_exit map stdlib_path;
-
-        | _ -> assert false
-      end;
-      Some {
-        Bsb_config_types.package_name = current_package;
-        package_install_path = Filename.dirname Bsb_global_paths.bsc_dir // Bsb_config.lib_ocaml;
-      }
-    end
+  | Some _ ->    
+    true
+
 
 
 
@@ -355,7 +333,7 @@ let interpret_json
          array from the bsconfig and set the backend_ref to the first entry, if any. *)
 
     (* The default situation is empty *)
-    let built_in_package = check_stdlib map per_proj_dir in
+    let built_in_package : bool = check_stdlib map  in
     
     let pp_flags : string option = 
       extract_string map Bsb_build_schemas.pp_flags (fun p -> 
@@ -410,7 +388,7 @@ let interpret_json
           js_post_build_cmd = (extract_js_post_build map per_proj_dir);
           package_specs = 
             (match package_kind with 
-             | Toplevel ->  Bsb_package_specs.from_map map                
+             | Toplevel ->  Bsb_package_specs.from_map ~cwd:per_proj_dir map                
              | Pinned_dependency x
              | Dependency x -> x);          
           file_groups = groups; 
@@ -434,7 +412,7 @@ let package_specs_from_bsconfig () =
   let json = Ext_json_parse.parse_json_from_file Literals.bsconfig_json in
   begin match json with
     | Obj {map} ->
-      Bsb_package_specs.from_map map,
+      Bsb_package_specs.from_map ~cwd:Bsb_global_paths.cwd map,
       extract_pinned_dependencies map
     | _ -> assert false
   end
diff --git a/jscomp/bsb/bsb_config_types.ml b/jscomp/bsb/bsb_config_types.ml
index ee508f615b..0627c18be5 100644
--- a/jscomp/bsb/bsb_config_types.ml
+++ b/jscomp/bsb/bsb_config_types.ml
@@ -61,7 +61,7 @@ type t =
     bs_dependencies : dependencies;
     bs_dev_dependencies : dependencies;
     pinned_dependencies : Set_string.t;
-    built_in_dependency : dependency option; 
+    built_in_dependency : bool; 
     warning : Bsb_warning.t;
     (*TODO: maybe we should always resolve bs-platform 
       so that we can calculate correct relative path in 
diff --git a/jscomp/bsb/bsb_merlin_gen.ml b/jscomp/bsb/bsb_merlin_gen.ml
index 3fe323fb8f..5eb9b01ad3 100644
--- a/jscomp/bsb/bsb_merlin_gen.ml
+++ b/jscomp/bsb/bsb_merlin_gen.ml
@@ -165,11 +165,13 @@ let merlin_file_gen ~per_proj_dir:(per_proj_dir:string)
         Buffer.add_string buffer merlin_b;
         Buffer.add_string buffer path ;
       );      
-    Ext_option.iter built_in_dependency (fun package -> 
-        let path = package.package_install_path in 
-        Buffer.add_string buffer (merlin_s ^ path );
-        Buffer.add_string buffer (merlin_b ^ path)                      
-      );
+    if built_in_dependency then (
+      let path = 
+        (Filename.dirname Bsb_global_paths.bsc_dir) 
+        // "lib" //"ocaml" in 
+      Buffer.add_string buffer (merlin_s ^ path );
+      Buffer.add_string buffer (merlin_b ^ path)                      
+    );
     let bsc_string_flag = bsc_flg_to_merlin_ocamlc_flg bsc_flags in 
     Buffer.add_string buffer bsc_string_flag ;
     Buffer.add_string buffer (warning_to_merlin_flg  warning); 
diff --git a/jscomp/bsb/bsb_ninja_gen.ml b/jscomp/bsb/bsb_ninja_gen.ml
index 3e593a0b14..fcb77a3103 100644
--- a/jscomp/bsb/bsb_ninja_gen.ml
+++ b/jscomp/bsb/bsb_ninja_gen.ml
@@ -237,7 +237,7 @@ let output_ninja_and_namespace_map
       ~gentype_config
       ~has_postbuild:js_post_build_cmd 
       ~pp_file
-      ~has_builtin:(built_in_dependency <> None)
+      ~has_builtin:built_in_dependency 
       ~reason_react_jsx
       ~package_specs
       ~namespace
diff --git a/jscomp/bsb/bsb_ninja_rule.ml b/jscomp/bsb/bsb_ninja_rule.ml
index ad17af3993..e76b808612 100644
--- a/jscomp/bsb/bsb_ninja_rule.ml
+++ b/jscomp/bsb/bsb_ninja_rule.ml
@@ -172,7 +172,8 @@ let make_custom_rules
     if read_cmi <> `is_cmi then begin 
       Ext_buffer.add_string buf " -bs-package-name ";
       Ext_buffer.add_string buf package_name;
-      Ext_buffer.add_string buf (Bsb_package_specs.package_flag_of_package_specs package_specs "$in_d")
+      Ext_buffer.add_string buf 
+        (Bsb_package_specs.package_flag_of_package_specs package_specs ~dirname:"$in_d")
     end;
     begin match bs_dependencies, bs_dev_dependencies with 
     | [], [] -> ()
diff --git a/jscomp/bsb/bsb_package_specs.ml b/jscomp/bsb/bsb_package_specs.ml
index 598f7e9428..5f618e7da7 100644
--- a/jscomp/bsb/bsb_package_specs.ml
+++ b/jscomp/bsb/bsb_package_specs.ml
@@ -37,11 +37,18 @@ type spec = {
   suffix : Ext_js_suffix.t 
 }
 
+(*FIXME: use assoc list instead *)
 module Spec_set = Set.Make( struct type t = spec 
     let compare = Pervasives.compare 
   end)
 
-type t = Spec_set.t 
+type t = {
+  modules : Spec_set.t;
+  runtime: string option;  
+  (* This has to be resolved as early as possible, since 
+    the path will be inherited in sub projects
+  *)
+}
 
 let (.?()) = Map_string.find_opt 
 
@@ -89,8 +96,8 @@ and from_json_single suffix (x : Ext_json_types.t) : spec =
   | Str {str = format; loc } ->    
       {format = supported_format format loc  ; in_source = false ; suffix }    
   | Obj {map; loc} ->
-    begin match Map_string.find_exn map "module" with
-      | Str {str = format} ->
+    begin match map .?("module") with
+      | Some(Str {str = format}) ->
         let in_source = 
           match map.?(Bsb_build_schemas.in_source) with
           | Some (True _) -> true
@@ -108,13 +115,10 @@ and from_json_single suffix (x : Ext_json_types.t) : spec =
             Bsb_exception.errorf ~loc:(Ext_json.loc_of x) "expect a string field"
           | None -> suffix in   
         {format = supported_format format loc ; in_source ; suffix}        
-      | Arr _ ->
-        Bsb_exception.errorf ~loc
-          "package-specs: when the configuration is an object, `module` field should be a string, not an array. If you want to pass multiple module specs, try turning package-specs into an array of objects (or strings) instead."
-      | _ ->
+      | Some _ ->
         Bsb_exception.errorf ~loc
-          "package-specs: the `module` field of the configuration object should be a string."
-      | exception _ ->
+          "package-specs: when the configuration is an object, `module` field should be a string, not an array. If you want to pass multiple module specs, try turning package-specs into an array of objects (or strings) instead."      
+      | None ->
         Bsb_exception.errorf ~loc
           "package-specs: when the configuration is an object, the `module` field is mandatory."
     end
@@ -144,12 +148,16 @@ let package_flag ({format; in_source; suffix } : spec) dir =
       (Ext_js_suffix.to_string suffix)
     )
 
+(* FIXME: we should adapt it *)    
 let package_flag_of_package_specs (package_specs : t) 
-    (dirname : string ) : string  = 
-  Spec_set.fold (fun format acc ->
+    ~(dirname : string ) : string  = 
+  let res = Spec_set.fold (fun format acc ->
       Ext_string.inter2 acc (package_flag format dirname )
-    ) package_specs Ext_string.empty
-
+    ) package_specs.modules Ext_string.empty in 
+  match package_specs.runtime with 
+  | None -> res
+  | Some x -> 
+    res ^ " -runtime " ^ x 
 let default_package_specs suffix = 
   Spec_set.singleton 
     { format = NodeJS ; in_source = false; suffix  }
@@ -161,7 +169,7 @@ let default_package_specs suffix =
 
 *)
 let get_list_of_output_js 
-    (package_specs : Spec_set.t)
+    (package_specs : t)
     (output_file_sans_extension : string)
     = 
   Spec_set.fold 
@@ -174,17 +182,17 @@ let get_list_of_output_js
         (if spec.in_source then Bsb_config.rev_lib_bs_prefix basename
         else Bsb_config.lib_bs_prefix_of_format spec.format // basename) 
        :: acc
-    ) package_specs []
+    ) package_specs.modules []
 
 
 let list_dirs_by
-  (package_specs : Spec_set.t)
+  (package_specs : t)
   (f : string -> unit)
   =  
   Spec_set.iter (fun (spec : spec)  -> 
     if not spec.in_source then     
       f (Bsb_config.top_prefix_of_format spec.format) 
-  ) package_specs 
+  ) package_specs.modules 
   
 type json_map = Ext_json_types.t Map_string.t 
 
@@ -201,10 +209,20 @@ let extract_bs_suffix_exn (map : json_map) : Ext_js_suffix.t =
     Bsb_exception.config_error config 
       "expect a string exteion like \".js\" here"
 
-let from_map map =  
+let from_map ~(cwd:string) map =  
   let suffix = extract_bs_suffix_exn map in   
-  match map.?(Bsb_build_schemas.package_specs) with 
+  let modules = match map.?(Bsb_build_schemas.package_specs) with 
   | Some x ->
     from_json suffix x 
-  | None ->  default_package_specs suffix
+  | None ->  default_package_specs suffix in 
+  let runtime = 
+    match map.?(Bsb_build_schemas.external_stdlib) with
+    | None -> None 
+    | Some(Str{str; _}) ->
+       Some (Bsb_pkg.resolve_bs_package ~cwd (Bsb_pkg_types.string_as_package str))
+    | _ -> assert false in   
+  {
+    runtime;  
+    modules 
+  }
 
diff --git a/jscomp/bsb/bsb_package_specs.mli b/jscomp/bsb/bsb_package_specs.mli
index 540a1364f3..3b7f933154 100644
--- a/jscomp/bsb/bsb_package_specs.mli
+++ b/jscomp/bsb/bsb_package_specs.mli
@@ -28,6 +28,7 @@ type t
 
 
 val from_map:
+  cwd:string ->
   Ext_json_types.t Map_string.t -> t 
 
 val get_list_of_output_js : 
@@ -39,8 +40,11 @@ val get_list_of_output_js :
   Sample output: {[ -bs-package-output commonjs:lib/js/jscomp/test]}
 *)
 val package_flag_of_package_specs : 
-  t -> string -> string
+  t -> 
+  dirname:string -> 
+  string
 
+(* used to ensure each dir does exist *)
 val list_dirs_by :   
   t -> 
   (string -> unit) -> 
diff --git a/jscomp/bsb/bsb_pkg.mli b/jscomp/bsb/bsb_pkg.mli
index 1ad08f65ee..86d4d50542 100644
--- a/jscomp/bsb/bsb_pkg.mli
+++ b/jscomp/bsb/bsb_pkg.mli
@@ -38,6 +38,7 @@ val resolve_bs_package :
     cwd:string ->  Bsb_pkg_types.t -> string 
 
 
+(** used by watcher *)    
 val to_list:    
   (Bsb_pkg_types.t  ->
    string ->
diff --git a/jscomp/bsb/bsb_pkg_types.ml b/jscomp/bsb/bsb_pkg_types.ml
index 48c4206dfb..ae88413168 100644
--- a/jscomp/bsb/bsb_pkg_types.ml
+++ b/jscomp/bsb/bsb_pkg_types.ml
@@ -95,7 +95,10 @@ let string_as_package (s : string) : t =
   if v = '@' then 
     let scope_id = 
         Ext_string.no_slash_idx s in 
-    assert (scope_id > 0);
+    assert (scope_id > 0); 
+    (* better-eror message for invalid scope package:
+      @rescript/std
+    *)
     Scope(
       String.sub s (scope_id + 1) (len - scope_id - 1),
       String.sub s 0 scope_id
diff --git a/jscomp/common/js_config.ml b/jscomp/common/js_config.ml
index 43b87c1c81..aba3327e90 100644
--- a/jscomp/common/js_config.ml
+++ b/jscomp/common/js_config.ml
@@ -92,3 +92,4 @@ let as_ppx = ref false
 
 let mono_empty_array = ref true
 
+let customize_runtime = ref None 
\ No newline at end of file
diff --git a/jscomp/common/js_config.mli b/jscomp/common/js_config.mli
index 69da84f706..719c49fa6d 100644
--- a/jscomp/common/js_config.mli
+++ b/jscomp/common/js_config.mli
@@ -100,3 +100,4 @@ val no_export: bool ref
 val as_ppx : bool ref 
 
 val mono_empty_array : bool ref
+val customize_runtime : string option ref 
\ No newline at end of file
diff --git a/jscomp/core/js_name_of_module_id.ml b/jscomp/core/js_name_of_module_id.ml
index 172d8f545a..9965b9db0d 100644
--- a/jscomp/core/js_name_of_module_id.ml
+++ b/jscomp/core/js_name_of_module_id.ml
@@ -80,7 +80,12 @@ let get_runtime_module_path
           (*Invariant: the package path to bs-platform, it is used to 
             calculate relative js path
           *)
-          ((Filename.dirname (Filename.dirname Sys.executable_name)) // dep_path // js_file)  
+          (match !Js_config.customize_runtime with 
+           | None ->
+             ((Filename.dirname (Filename.dirname Sys.executable_name)) // dep_path // js_file)
+           | Some path -> 
+             path //dep_path // js_file 
+          )  
 
 
 
@@ -142,6 +147,9 @@ let string_of_module_id
                   which is guaranteed by [-bs-package-output]
               *)
           else  
+          if Js_packages_info.is_runtime_package dep_package_info then 
+            get_runtime_module_path dep_module_id current_package_info module_system
+          else 
             begin match module_system with 
               | NodeJS | Es6 -> 
                 dep_pkg.pkg_rel_path // js_file
diff --git a/jscomp/core/js_packages_info.ml b/jscomp/core/js_packages_info.ml
index 27eab46e07..a3a808fe61 100644
--- a/jscomp/core/js_packages_info.ml
+++ b/jscomp/core/js_packages_info.ml
@@ -94,7 +94,19 @@ let runtime_test_package_specs : t = {
   name = Pkg_runtime; 
   module_systems = []
 }
-let same_package_by_name (x : t) (y : t) = x.name = y.name 
+
+let same_package_by_name (x : t) (y : t) =
+  match x.name with 
+  | Pkg_empty -> 
+    y.name = Pkg_empty
+  | Pkg_runtime -> 
+    y.name = Pkg_runtime 
+  | Pkg_normal s -> 
+    begin match y.name with 
+    | Pkg_normal y -> s = y
+    | Pkg_empty | Pkg_runtime -> false
+    end
+   
 
 let is_runtime_package (x : t) = 
     x.name = Pkg_runtime
diff --git a/jscomp/main/js_main.ml b/jscomp/main/js_main.ml
index 075b401397..dc83d42971 100644
--- a/jscomp/main/js_main.ml
+++ b/jscomp/main/js_main.ml
@@ -32,7 +32,18 @@ let setup_error_printer (syntax_kind : [ `ml | `reason | `rescript ])=
 
 
   
-  
+let setup_runtime_path path = 
+  let u0 = Filename.dirname path in 
+  let std = Filename.basename path in 
+  let _path = Filename.dirname u0 in 
+  let rescript = Filename.basename u0 in 
+  (match rescript.[0] with 
+   | '@' -> (* scoped package *)
+     Bs_version.package_name := rescript ^ "/" ^ std;
+   | _ -> Bs_version.package_name := std
+   | exception _ -> 
+     Bs_version.package_name := std);
+  Js_config.customize_runtime := Some path
 
 let handle_reason (type a) (kind : a Ml_binary.kind) sourcefile ppf  = 
   setup_error_printer `reason;
@@ -443,6 +454,8 @@ let buckle_script_flags : (string * Bsc_args.spec * string) array =
     "<list>  Enable or disable error status for warnings according\n\
          to <list>.  See option -w for the syntax of <list>.\n\
          Default setting is " ^ Bsc_warnings.defaults_warn_error;    
+    "-runtime",string_call setup_runtime_path,     
+    "*internal* Set the runtime directory";
     "-make-runtime", unit_call Js_packages_state.make_runtime,
     "*internal* make runtime library";  
     "-make-runtime-test", unit_call Js_packages_state.make_runtime_test,
diff --git a/lib/4.06.1/bsb.ml b/lib/4.06.1/bsb.ml
index f25c7453c6..637cceab9d 100644
--- a/lib/4.06.1/bsb.ml
+++ b/lib/4.06.1/bsb.ml
@@ -1928,6 +1928,7 @@ let export_none = "none"
 
 
 let use_stdlib = "use-stdlib"
+let external_stdlib = "external-stdlib"
 let reason = "reason"
 let react_jsx = "react-jsx"
 
@@ -6068,7 +6069,10 @@ let string_as_package (s : string) : t =
   if v = '@' then 
     let scope_id = 
         Ext_string.no_slash_idx s in 
-    assert (scope_id > 0);
+    assert (scope_id > 0); 
+    (* better-eror message for invalid scope package:
+      @rescript/std
+    *)
     Scope(
       String.sub s (scope_id + 1) (len - scope_id - 1),
       String.sub s 0 scope_id
@@ -6557,36 +6561,55 @@ let () =
     )
 
 end
-module Ext_js_suffix
-= struct
-#1 "ext_js_suffix.ml"
-type t = 
-  | Js 
-  | Bs_js   
-  | Mjs
-  | Cjs
-  | Unknown_extension
-let to_string (x : t) =   
-  match x with 
-  | Js -> Literals.suffix_js
-  | Bs_js -> Literals.suffix_bs_js  
-  | Mjs -> Literals.suffix_mjs
-  | Cjs -> Literals.suffix_cjs
-  | Unknown_extension -> assert false
+module Ext_color : sig 
+#1 "ext_color.mli"
+(* 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
+ * or link a "work that uses the Library" with a publicly distributed version
+ * of this file to produce a combined library or application, then distribute
+ * that combined work under the terms of your choosing, with no requirement
+ * to comply with the obligations normally placed on you by section 4 of the
+ * LGPL version 3 (or the corresponding section of a later version of the LGPL
+ * should you choose to use a later version).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
+type color 
+  = Black
+  | Red
+  | Green
+  | Yellow
+  | Blue
+  | Magenta
+  | Cyan
+  | White
 
-let of_string (x : string) : t =
-  match () with 
-  | () when x = Literals.suffix_js -> Js 
-  | () when x = Literals.suffix_bs_js -> Bs_js       
-  | () when x = Literals.suffix_mjs -> Mjs
-  | () when x = Literals.suffix_cjs -> Cjs 
-  | _ -> Unknown_extension
+type style 
+  = FG of color 
+  | BG of color 
+  | Bold
+  | Dim
 
+(** Input is the tag for example `@{<warning>@}` return escape code *)
+val ansi_of_tag : string -> string 
 
-end
-module Ext_filename : sig 
-#1 "ext_filename.mli"
+val reset_lit : string
+
+end = struct
+#1 "ext_color.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
  * 
  * This program is free software: you can redistribute it and/or modify
@@ -6614,67 +6637,83 @@ module Ext_filename : sig
 
 
 
+type color 
+  = Black
+  | Red
+  | Green
+  | Yellow
+  | Blue
+  | Magenta
+  | Cyan
+  | White
 
-(* TODO:
-   Change the module name, this code is not really an extension of the standard 
-    library but rather specific to JS Module name convention. 
-*)
-
-
-
+type style 
+  = FG of color 
+  | BG of color 
+  | Bold
+  | Dim
 
 
-(** An extension module to calculate relative path follow node/npm style. 
-    TODO : this short name will have to change upon renaming the file.
-*)
+(* let ansi_of_color = function
+  | Black -> "0"
+  | Red -> "1"
+  | Green -> "2"
+  | Yellow -> "3"
+  | Blue -> "4"
+  | Magenta -> "5"
+  | Cyan -> "6"
+  | White -> "7" *)
 
-val is_dir_sep : 
-  char -> bool 
+let code_of_style = function
+  | FG Black -> "30"
+  | FG Red -> "31"
+  | FG Green -> "32"
+  | FG Yellow -> "33"
+  | FG Blue -> "34"
+  | FG Magenta -> "35"
+  | FG Cyan -> "36"
+  | FG White -> "37"
   
-val maybe_quote:
-  string -> 
-  string
+  | BG Black -> "40"
+  | BG Red -> "41"
+  | BG Green -> "42"
+  | BG Yellow -> "43"
+  | BG Blue -> "44"
+  | BG Magenta -> "45"
+  | BG Cyan -> "46"
+  | BG White -> "47"
 
-val chop_extension_maybe:
-  string -> 
-  string
+  | Bold -> "1"
+  | Dim -> "2"
 
-(* return an empty string if no extension found *)  
-val get_extension_maybe:   
-  string -> 
-  string
 
 
-val new_extension:  
-  string -> 
-  string -> 
-  string
+(** TODO: add more styles later *)
+let style_of_tag s = match s with
+  | "error" -> [Bold; FG Red]
+  | "warning" -> [Bold; FG Magenta]
+  | "info" -> [Bold; FG Yellow]
+  | "dim" -> [Dim]
+  | "filename" -> [FG Cyan]
+  | _ -> []
 
-val chop_all_extensions_maybe:
-  string -> 
-  string  
+let ansi_of_tag s = 
+  let l = style_of_tag s in
+  let s =  String.concat ";" (Ext_list.map l  code_of_style) in
+  "\x1b[" ^ s ^ "m"
 
-(* OCaml specific abstraction*)
-val module_name:  
-  string ->
-  string
 
 
+let reset_lit = "\x1b[0m" 
 
 
-type module_info = {
-  module_name : string ;
-  case : bool;
-}   
 
 
 
-val as_module:
-  basename:string -> 
-  module_info option
-end = struct
-#1 "ext_filename.ml"
-(* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+end
+module Bsb_log : sig 
+#1 "bsb_log.mli"
+(* Copyright (C) 2017 Authors of BuckleScript
  * 
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -6699,166 +6738,146 @@ end = struct
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 
+val setup : unit -> unit 
 
+type level = 
+  | Debug
+  | Info 
+  | Warn
+  | Error 
 
-let is_dir_sep_unix c = c = '/'
-let is_dir_sep_win_cygwin c = 
-  c = '/' || c = '\\' || c = ':'
+val log_level : level ref
 
-let is_dir_sep = 
-  if Sys.unix then is_dir_sep_unix else is_dir_sep_win_cygwin
+type 'a fmt = Format.formatter -> ('a, Format.formatter, unit) format -> 'a
 
-(* reference ninja.cc IsKnownShellSafeCharacter *)
-let maybe_quote ( s : string) = 
-  let noneed_quote = 
-    Ext_string.for_all s (function
-        | '0' .. '9' 
-        | 'a' .. 'z' 
-        | 'A' .. 'Z'
-        | '_' | '+' 
-        | '-' | '.'
-        | '/' 
-        | '@' -> true
-        | _ -> false
-      )  in 
-  if noneed_quote then
-    s
-  else Filename.quote s 
+type 'a log = ('a, Format.formatter, unit) format -> 'a
 
+val verbose : unit -> unit 
+val debug  : 'a log
+val info : 'a log 
+val warn : 'a log 
+val error : 'a log
 
-let chop_extension_maybe name =
-  let rec search_dot i =
-    if i < 0 || is_dir_sep (String.unsafe_get name i) then name
-    else if String.unsafe_get name i = '.' then String.sub name 0 i
-    else search_dot (i - 1) in
-  search_dot (String.length name - 1)
+val info_args : string array -> unit
 
-let get_extension_maybe name =   
-  let name_len = String.length name in  
-  let rec search_dot name i name_len =
-    if i < 0 || is_dir_sep (String.unsafe_get name i) then ""
-    else if String.unsafe_get name i = '.' then String.sub name i (name_len - i)
-    else search_dot name (i - 1) name_len in
-  search_dot name (name_len - 1) name_len
+end = struct
+#1 "bsb_log.ml"
+(* Copyright (C) 2017- Authors of BuckleScript
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * In addition to the permissions granted to you by the LGPL, you may combine
+ * or link a "work that uses the Library" with a publicly distributed version
+ * of this file to produce a combined library or application, then distribute
+ * that combined work under the terms of your choosing, with no requirement
+ * to comply with the obligations normally placed on you by section 4 of the
+ * LGPL version 3 (or the corresponding section of a later version of the LGPL
+ * should you choose to use a later version).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
-let chop_all_extensions_maybe name =
-  let rec search_dot i last =
-    if i < 0 || is_dir_sep (String.unsafe_get name i) then 
-      (match last with 
-      | None -> name
-      | Some i -> String.sub name 0 i)  
-    else if String.unsafe_get name i = '.' then 
-      search_dot (i - 1) (Some i)
-    else search_dot (i - 1) last in
-  search_dot (String.length name - 1) None
 
 
-let new_extension name (ext : string) = 
-  let rec search_dot name i ext =
-    if i < 0 || is_dir_sep (String.unsafe_get name i) then 
-      name ^ ext 
-    else if String.unsafe_get name i = '.' then 
-      let ext_len = String.length ext in
-      let buf = Bytes.create (i + ext_len) in 
-      Bytes.blit_string name 0 buf 0 i;
-      Bytes.blit_string ext 0 buf i ext_len;
-      Bytes.unsafe_to_string buf
-    else search_dot name (i - 1) ext  in
-  search_dot name (String.length name - 1) ext
+let ninja_ansi_forced = lazy 
+  (try Sys.getenv "NINJA_ANSI_FORCED" with 
+    Not_found  ->""
+  )  
+let color_enabled = lazy (Unix.isatty Unix.stdout)
 
+(* same logic as [ninja.exe] *)
+let get_color_enabled () = 
+  let colorful = 
+    match ninja_ansi_forced with 
+    | lazy "1" -> true     
+    | lazy ("0" | "false") -> false
+    | _ ->
+      Lazy.force color_enabled  in 
+  colorful 
 
 
-(** TODO: improve efficiency
-   given a path, calcuate its module name 
-   Note that `ocamlc.opt -c aa.xx.mli` gives `aa.xx.cmi`
-   we can not strip all extensions, otherwise
-   we can not tell the difference between "x.cpp.ml" 
-   and "x.ml"
-*)
-let module_name name = 
-  let rec search_dot i  name =
-    if i < 0  then 
-      Ext_string.capitalize_ascii name
-    else 
-    if String.unsafe_get name i = '.' then 
-      Ext_string.capitalize_sub name i 
-    else 
-      search_dot (i - 1) name in  
-  let name = Filename.basename  name in 
-  let name_len = String.length name in 
-  search_dot (name_len - 1)  name 
 
-type module_info = {
-  module_name : string ;
-  case : bool;
-} 
+let color_functions : Format.formatter_tag_functions = {
+  mark_open_tag = (fun s ->  if get_color_enabled () then  Ext_color.ansi_of_tag s else Ext_string.empty) ;
+  mark_close_tag = (fun _ ->  if get_color_enabled () then Ext_color.reset_lit else Ext_string.empty);
+  print_open_tag = (fun _ -> ());
+  print_close_tag = (fun _ -> ())
+}
 
+(* let set_color ppf =
+  Format.pp_set_formatter_tag_functions ppf color_functions *)
 
 
-let rec valid_module_name_aux name off len =
-  if off >= len then true 
-  else 
-    let c = String.unsafe_get name off in 
-    match c with 
-    | 'A'..'Z' | 'a'..'z' | '0'..'9' | '_' | '\'' | '.' | '[' | ']' -> 
-      valid_module_name_aux name (off + 1) len 
-    | _ -> false
+let setup () = 
+  begin 
+    Format.pp_set_mark_tags Format.std_formatter true ;
+    Format.pp_set_mark_tags Format.err_formatter true;
+    Format.pp_set_formatter_tag_functions 
+      Format.std_formatter color_functions;
+    Format.pp_set_formatter_tag_functions
+      Format.err_formatter color_functions
+  end
 
-type state = 
-  | Invalid
-  | Upper
-  | Lower
+type level = 
+  | Debug
+  | Info 
+  | Warn
+  | Error 
 
-let valid_module_name name len =     
-  if len = 0 then Invalid
-  else 
-    let c = String.unsafe_get name 0 in 
-    match c with 
-    | 'A' .. 'Z'
-      -> 
-      if valid_module_name_aux name 1 len then 
-        Upper
-      else Invalid  
-    | 'a' .. 'z' 
-    | '0' .. '9'
-    | '_'
-    | '[' 
-    | ']'
-      -> 
-      if valid_module_name_aux name 1 len then
-        Lower
-      else Invalid
-    | _ -> Invalid
+let int_of_level (x : level) = 
+  match x with 
+  | Debug -> 0 
+  | Info -> 1 
+  | Warn -> 2 
+  | Error -> 3 
 
+let log_level = ref Warn
+
+let verbose () =
+   log_level := Debug
+let dfprintf level fmt = 
+  if int_of_level level >= int_of_level  !log_level then 
+    Format.fprintf fmt 
+  else Format.ifprintf fmt  
+
+type 'a fmt = 
+  Format.formatter -> ('a, Format.formatter, unit) format -> 'a
+type 'a log = 
+  ('a, Format.formatter, unit) format -> 'a
+
+let debug fmt = dfprintf  Debug Format.std_formatter fmt 
+let info fmt = dfprintf Info Format.std_formatter fmt
+let warn fmt = dfprintf Warn Format.err_formatter fmt 
+let error fmt = dfprintf Error Format.err_formatter fmt
+
+
+let info_args (args : string array) = 
+  if int_of_level Info >= int_of_level !log_level then 
+    begin
+      for i  = 0 to Array.length args - 1 do
+        Format.pp_print_string Format.std_formatter (Array.unsafe_get args i) ;
+        Format.pp_print_string Format.std_formatter Ext_string.single_space;
+      done ;
+      Format.pp_print_newline Format.std_formatter ()
+    end
+  else ()
+  
 
-let as_module ~basename =
-  let rec search_dot i  name name_len =
-    if i < 0  then
-      (* Input e.g, [a_b] *)
-      match valid_module_name name name_len with 
-      | Invalid -> None 
-      | Upper ->  Some {module_name = name; case = true }
-      | Lower -> Some {module_name = Ext_string.capitalize_ascii name; case = false}
-    else 
-    if String.unsafe_get name i = '.' then 
-      (*Input e.g, [A_b] *)
-      match valid_module_name  name i with 
-      | Invalid -> None 
-      | Upper -> 
-        Some {module_name = Ext_string.capitalize_sub name i; case = true}
-      | Lower -> 
-        Some {module_name = Ext_string.capitalize_sub name i; case = false}
-    else 
-      search_dot (i - 1) name name_len in  
-  let name_len = String.length basename in       
-  search_dot (name_len - 1)  basename name_len
-    
 end
-module Ext_js_file_kind
-= struct
-#1 "ext_js_file_kind.ml"
+module Bsb_real_path : sig 
+#1 "bsb_real_path.mli"
+
 (* Copyright (C) 2020- Authors of BuckleScript
- * 
+ *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
@@ -6876,28 +6895,58 @@ module Ext_js_file_kind
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU Lesser General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
-type case = 
-  | Upper
-  | Little 
 
-type t = {
-  case : case; 
-  suffix : Ext_js_suffix.t;
-}
 
+val is_same_paths_via_io : string -> string -> bool 
+
+end = struct
+#1 "bsb_real_path.ml"
+let (//) = Filename.concat
+
+
+
+let normalize_exn (s : string) : string = 
+  let old_cwd = Sys.getcwd () in 
+  Unix.chdir s ;
+  let normalized = Sys.getcwd () in 
+  Unix.chdir old_cwd; 
+  normalized
+
+let real_path p =
+  match Sys.is_directory p with
+  | exception _ ->
+    let rec resolve dir =
+      if Sys.file_exists dir then normalize_exn dir else
+      let parent = Filename.dirname dir in
+      if dir = parent then dir
+      else  (resolve parent) // (Filename.basename dir)
+    in
+    let p =
+      if Filename.is_relative p then (Sys.getcwd ()) // p
+      else p
+    in
+    resolve p
+  | true -> normalize_exn p
+  | false ->
+    let dir = normalize_exn (Filename.dirname p) in
+    match Filename.basename p with
+    | "." -> dir
+    | base -> dir // base
+
+
+let is_same_paths_via_io a b =
+  if a = b
+  then true
+  else (real_path a) = (real_path b)
 
-let any_runtime_kind = {
-  case = Little; 
-  suffix = Ext_js_suffix.Js
-}
 end
-module Ext_namespace : sig 
-#1 "ext_namespace.mli"
-(* Copyright (C) 2017- Authors of BuckleScript
+module Ext_util : sig 
+#1 "ext_util.mli"
+(* 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
@@ -6922,49 +6971,13 @@ module Ext_namespace : sig
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 
-
-val try_split_module_name :
-  string -> (string * string ) option
-
-
-
-(* Note  we have to output uncapitalized file Name, 
-   or at least be consistent, since by reading cmi file on Case insensitive OS, we don't really know it is `list.cmi` or `List.cmi`, so that `require (./list.js)` or `require(./List.js)`
-   relevant issues: #1609, #913  
-
-   #1933 when removing ns suffix, don't pass the bound
-   of basename
-*)
-val change_ext_ns_suffix :  
-  string -> 
-  string ->
-  string
+ 
+val power_2_above : int -> int -> int
 
 
-  
-(** [js_name_of_modulename ~little A-Ns]
-  *)
-val js_name_of_modulename : 
-  string -> 
-  Ext_js_file_kind.case -> 
-  Ext_js_suffix.t ->
-  string
-
-(* TODO handle cases like 
-   '@angular/core'
-   its directory structure is like 
-   {[
-     @angular
-     |-------- core
-   ]}
-*)
-val is_valid_npm_package_name : string -> bool 
-
-val namespace_of_package_name : string -> string
-
+val stats_to_string : Hashtbl.statistics -> string 
 end = struct
-#1 "ext_namespace.ml"
-
+#1 "ext_util.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
  * 
  * This program is free software: you can redistribute it and/or modify
@@ -6989,396 +7002,419 @@ end = struct
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
+(**
+   {[
+     (power_2_above 16 63 = 64)
+       (power_2_above 16 76 = 128)
+   ]}
+*)
+let rec power_2_above x n =
+  if x >= n then x
+  else if x * 2 > Sys.max_array_length then x
+  else power_2_above (x * 2) n
 
 
+let stats_to_string ({num_bindings; num_buckets; max_bucket_length; bucket_histogram} : Hashtbl.statistics) = 
+  Printf.sprintf 
+    "bindings: %d,buckets: %d, longest: %d, hist:[%s]" 
+    num_bindings 
+    num_buckets 
+    max_bucket_length
+    (String.concat "," (Array.to_list (Array.map string_of_int bucket_histogram)))
+end
+module Hash_gen
+= struct
+#1 "hash_gen.ml"
+(***********************************************************************)
+(*                                                                     *)
+(*                                OCaml                                *)
+(*                                                                     *)
+(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
+(*                                                                     *)
+(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
+(*  en Automatique.  All rights reserved.  This file is distributed    *)
+(*  under the terms of the GNU Library General Public License, with    *)
+(*  the special exception on linking described in file ../LICENSE.     *)
+(*                                                                     *)
+(***********************************************************************)
 
+(* Hash tables *)
 
-let rec rindex_rec s i  =
-  if i < 0 then i else
-    let char = String.unsafe_get s i in
-    if Ext_filename.is_dir_sep char  then -1 
-    else if char = Literals.ns_sep_char then i 
-    else
-      rindex_rec s (i - 1) 
 
-let change_ext_ns_suffix name ext =
-  let i = rindex_rec name (String.length name - 1)  in 
-  if i < 0 then name ^ ext
-  else String.sub name 0 i ^ ext (* FIXME: micro-optimizaiton*)
 
-let try_split_module_name name = 
-  let len = String.length name in 
-  let i = rindex_rec name (len - 1)  in 
-  if i < 0 then None 
-  else 
-    Some (String.sub name (i+1) (len - i - 1),
-          String.sub name 0 i )
 
+(* We do dynamic hashing, and resize the table and rehash the elements
+   when buckets become too long. *)
 
+type ('a, 'b) bucket =
+  | Empty
+  | Cons of {
+      mutable key : 'a ; 
+      mutable data : 'b ; 
+      mutable next :  ('a, 'b) bucket
+    }
 
-  
+type ('a, 'b) t =
+  { mutable size: int;                        (* number of entries *)
+    mutable data: ('a, 'b) bucket array;  (* the buckets *)
+    initial_size: int;                        (* initial array size *)
+  }
 
-let js_name_of_modulename s (case : Ext_js_file_kind.case) suffix : string = 
-  let s = match case with 
-    | Little -> 
-      Ext_string.uncapitalize_ascii s
-    | Upper -> s  in 
-  change_ext_ns_suffix s  (Ext_js_suffix.to_string suffix)
 
-(* https://docs.npmjs.com/files/package.json 
-   Some rules:
-   The name must be less than or equal to 214 characters. This includes the scope for scoped packages.
-   The name can't start with a dot or an underscore.
-   New packages must not have uppercase letters in the name.
-   The name ends up being part of a URL, an argument on the command line, and a folder name. Therefore, the name can't contain any non-URL-safe characters.
-*)
-let is_valid_npm_package_name (s : string) = 
-  let len = String.length s in 
-  len <= 214 && (* magic number forced by npm *)
-  len > 0 &&
-  match String.unsafe_get s 0 with 
-  | 'a' .. 'z' | '@' -> 
-    Ext_string.for_all_from s 1 
-      (fun x -> 
-         match x with 
-         |  'a'..'z' | '0'..'9' | '_' | '-' -> true
-         | _ -> false )
-  | _ -> false 
 
+let create  initial_size =
+  let s = Ext_util.power_2_above 16 initial_size in
+  { initial_size = s; size = 0; data = Array.make s Empty }
 
-let namespace_of_package_name (s : string) : string = 
-  let len = String.length s in 
-  let buf = Ext_buffer.create len in 
-  let add capital ch = 
-    Ext_buffer.add_char buf 
-      (if capital then 
-         (Char.uppercase_ascii ch)
-       else ch) in    
-  let rec aux capital off len =     
-    if off >= len then ()
-    else 
-      let ch = String.unsafe_get s off in
-      match ch with 
-      | 'a' .. 'z' 
-      | 'A' .. 'Z' 
-      | '0' .. '9'
-      | '_'
-        ->
-        add capital ch ; 
-        aux false (off + 1) len 
-      | '/'
-      | '-' -> 
-        aux true (off + 1) len 
-      | _ -> aux capital (off+1) len
-  in 
-  aux true 0 len ;
-  Ext_buffer.contents buf 
+let clear h =
+  h.size <- 0;
+  let len = Array.length h.data in
+  for i = 0 to len - 1 do
+    Array.unsafe_set h.data i  Empty  
+  done
 
-end
-module Bsb_package_specs : sig 
-#1 "bsb_package_specs.mli"
-(* Copyright (C) 2017 Authors of BuckleScript
- * 
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- * 
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
+let reset h =
+  h.size <- 0;
+  h.data <- Array.make h.initial_size Empty
 
-type t
 
+let length h = h.size
 
+let resize indexfun h =
+  let odata = h.data in
+  let osize = Array.length odata in
+  let nsize = osize * 2 in
+  if nsize < Sys.max_array_length then begin
+    let ndata = Array.make nsize Empty in
+    let ndata_tail = Array.make nsize Empty in 
+    h.data <- ndata;          (* so that indexfun sees the new bucket count *)
+    let rec insert_bucket = function
+        Empty -> ()
+      | Cons {key; next} as cell ->
+        let nidx = indexfun h key in
+        begin match Array.unsafe_get ndata_tail nidx with 
+        | Empty -> 
+          Array.unsafe_set ndata nidx cell
+        | Cons tail ->
+          tail.next <- cell  
+        end;
+        Array.unsafe_set ndata_tail nidx cell;
+        insert_bucket next
+    in
+    for i = 0 to osize - 1 do
+      insert_bucket (Array.unsafe_get odata i)
+    done;
+    for i = 0 to nsize - 1 do 
+      match Array.unsafe_get ndata_tail i with 
+      | Empty -> ()  
+      | Cons tail -> tail.next <- Empty
+    done   
+  end
 
 
-val from_map:
-  Ext_json_types.t Map_string.t -> t 
 
-val get_list_of_output_js : 
-  t -> 
-  string -> 
-  string list
+let iter h f =
+  let rec do_bucket = function
+    | Empty ->
+      ()
+    | Cons l  ->
+      f l.key l.data; do_bucket l.next in
+  let d = h.data in
+  for i = 0 to Array.length d - 1 do
+    do_bucket (Array.unsafe_get d i)
+  done
 
-(**
-  Sample output: {[ -bs-package-output commonjs:lib/js/jscomp/test]}
-*)
-val package_flag_of_package_specs : 
-  t -> string -> string
+let fold h init f =
+  let rec do_bucket b accu =
+    match b with
+      Empty ->
+      accu
+    | Cons l ->
+      do_bucket l.next (f l.key l.data accu) in
+  let d = h.data in
+  let accu = ref init in
+  for i = 0 to Array.length d - 1 do
+    accu := do_bucket (Array.unsafe_get d i) !accu
+  done;
+  !accu
 
-val list_dirs_by :   
-  t -> 
-  (string -> unit) -> 
-  unit
-end = struct
-#1 "bsb_package_specs.ml"
-(* Copyright (C) 2017 Authors of BuckleScript
- * 
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- * 
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
+let to_list h f =
+  fold h [] (fun k data acc -> f k data :: acc)  
 
 
-let (//) = Ext_path.combine 
 
 
+let rec small_bucket_mem (lst : _ bucket) eq key  =
+  match lst with 
+  | Empty -> false 
+  | Cons lst -> 
+    eq  key lst.key ||
+    match lst.next with
+    | Empty -> false 
+    | Cons lst -> 
+      eq key lst.key  || 
+      match lst.next with 
+      | Empty -> false 
+      | Cons lst -> 
+        eq key lst.key  ||
+        small_bucket_mem lst.next eq key 
 
-(* TODO: sync up with {!Js_packages_info.module_system}  *)
-type format = Ext_module_system.t = 
-  | NodeJS | Es6 | Es6_global
 
-type spec = {
-  format : format;
-  in_source : bool;
-  suffix : Ext_js_suffix.t 
-}
+let rec small_bucket_opt eq key (lst : _ bucket) : _ option =
+  match lst with 
+  | Empty -> None 
+  | Cons lst -> 
+    if eq  key lst.key then Some lst.data else 
+      match lst.next with
+      | Empty -> None 
+      | Cons lst -> 
+        if eq key lst.key then Some lst.data else 
+          match lst.next with 
+          | Empty -> None 
+          | Cons lst -> 
+            if eq key lst.key  then Some lst.data else 
+              small_bucket_opt eq key lst.next
 
-module Spec_set = Set.Make( struct type t = spec 
-    let compare = Pervasives.compare 
-  end)
 
-type t = Spec_set.t 
+let rec small_bucket_key_opt eq key (lst : _ bucket) : _ option =
+  match lst with 
+  | Empty -> None 
+  | Cons {key=k;  next} -> 
+    if eq  key k then Some k else 
+      match next with
+      | Empty -> None 
+      | Cons {key=k; next} -> 
+        if eq key k then Some k else 
+          match next with 
+          | Empty -> None 
+          | Cons {key=k; next} -> 
+            if eq key k  then Some k else 
+              small_bucket_key_opt eq key next
 
-let (.?()) = Map_string.find_opt 
 
-let bad_module_format_message_exn ~loc format =
-  Bsb_exception.errorf ~loc "package-specs: `%s` isn't a valid output module format. It has to be one of:  %s, %s or %s"
-    format
-    Literals.commonjs
-    Literals.es6
-    Literals.es6_global
+let rec small_bucket_default eq key default (lst : _ bucket) =
+  match lst with 
+  | Empty -> default 
+  | Cons lst -> 
+    if eq  key lst.key then  lst.data else 
+      match lst.next with
+      | Empty -> default 
+      | Cons lst -> 
+        if eq key lst.key then  lst.data else 
+          match lst.next with 
+          | Empty -> default 
+          | Cons lst -> 
+            if eq key lst.key  then lst.data else 
+              small_bucket_default eq key default lst.next
 
-let supported_format (x : string) loc = 
-  if x = Literals.commonjs then NodeJS
-  else if x = Literals.es6 then Es6
-  else if x = Literals.es6_global then Es6_global
-  else bad_module_format_message_exn ~loc x 
+let rec remove_bucket 
+    h  (i : int)
+    key 
+    ~(prec : _ bucket) 
+    (buck : _ bucket) 
+    eq_key = 
+  match buck with   
+  | Empty ->
+    ()
+  | Cons {key=k; next }  ->
+    if eq_key k key 
+    then begin
+      h.size <- h.size - 1;
+      match prec with
+      | Empty -> Array.unsafe_set h.data i  next
+      | Cons c -> c.next <- next
+    end
+    else remove_bucket h i key ~prec:buck next eq_key
 
-let string_of_format (x : format) =
-  match x with 
-  | NodeJS -> Literals.commonjs
-  | Es6 -> Literals.es6
-  | Es6_global -> Literals.es6_global
+let rec replace_bucket key data (buck : _ bucket) eq_key = 
+  match buck with   
+  | Empty ->
+    true
+  | Cons slot ->
+    if eq_key slot.key key
+    then (slot.key <- key; slot.data <- data; false)
+    else replace_bucket key data slot.next eq_key
 
+module type S = sig 
+  type key
+  type 'a t
+  val create: int -> 'a t
+  val clear: 'a t -> unit
+  val reset: 'a t -> unit
 
-let rec from_array suffix (arr : Ext_json_types.t array) : Spec_set.t =
-  let spec = ref Spec_set.empty in
-  let has_in_source = ref false in
-  Ext_array.iter arr (fun x ->
-      let result = from_json_single suffix x  in
-      if result.in_source then 
-        (
-          if not !has_in_source then
-            has_in_source:= true
-          else 
-            Bsb_exception.errorf 
-              ~loc:(Ext_json.loc_of x) 
-              "package-specs: we've detected two module formats that are both configured to be in-source." 
-        );
-      spec := Spec_set.add result !spec
-    );
-  !spec
+  val add: 'a t -> key -> 'a -> unit
+  val add_or_update: 
+    'a t -> 
+    key -> 
+    update:('a -> 'a) -> 
+    'a -> unit 
+  val remove: 'a t -> key -> unit
+  val find_exn: 'a t -> key -> 'a
+  val find_all: 'a t -> key -> 'a list
+  val find_opt: 'a t -> key  -> 'a option
 
-(* TODO: FIXME: better API without mutating *)
-and from_json_single suffix (x : Ext_json_types.t) : spec =
-  match x with
-  | Str {str = format; loc } ->    
-      {format = supported_format format loc  ; in_source = false ; suffix }    
-  | Obj {map; loc} ->
-    begin match Map_string.find_exn map "module" with
-      | Str {str = format} ->
-        let in_source = 
-          match map.?(Bsb_build_schemas.in_source) with
-          | Some (True _) -> true
-          | Some _
-          | None -> false
-        in        
-        let suffix = 
-          match map.?("suffix") with
-          | Some (Str {str = suffix; loc}) ->
-            let s = Ext_js_suffix.of_string suffix in 
-            if s = Unknown_extension then 
-              Bsb_exception.errorf ~loc "expect .js,.bs.js,.mjs or .cjs"
-            else  s 
-          | Some _ -> 
-            Bsb_exception.errorf ~loc:(Ext_json.loc_of x) "expect a string field"
-          | None -> suffix in   
-        {format = supported_format format loc ; in_source ; suffix}        
-      | Arr _ ->
-        Bsb_exception.errorf ~loc
-          "package-specs: when the configuration is an object, `module` field should be a string, not an array. If you want to pass multiple module specs, try turning package-specs into an array of objects (or strings) instead."
-      | _ ->
-        Bsb_exception.errorf ~loc
-          "package-specs: the `module` field of the configuration object should be a string."
-      | exception _ ->
-        Bsb_exception.errorf ~loc
-          "package-specs: when the configuration is an object, the `module` field is mandatory."
-    end
-  | _ -> Bsb_exception.errorf ~loc:(Ext_json.loc_of x)
-           "package-specs: we expect either a string or an object."
+  (** return the key found in the hashtbl.
+      Use case: when you find the key existed in hashtbl, 
+      you want to use the one stored in the hashtbl. 
+      (they are semantically equivlanent, but may have other information different) 
+  *)
+  val find_key_opt: 'a t -> key -> key option 
 
-let  from_json suffix (x : Ext_json_types.t) : Spec_set.t =
-  match x with
-  | Arr {content ; _} -> from_array suffix content
-  | _ -> Spec_set.singleton (from_json_single suffix x )
+  val find_default: 'a t -> key -> 'a -> 'a 
 
-let bs_package_output = "-bs-package-output"
-[@@@warning "+9"]
-(** Assume input is valid 
-    coordinate with command line flag 
-    {[ -bs-package-output commonjs:lib/js/jscomp/test:.js ]}    
-*)
-let package_flag ({format; in_source; suffix } : spec) dir =
-  Ext_string.inter2
-    bs_package_output 
-    (Ext_string.concat5
-       (string_of_format format)
-       Ext_string.single_colon
-       (if in_source then dir else
-        Bsb_config.top_prefix_of_format format // dir)
-      Ext_string.single_colon  
-      (Ext_js_suffix.to_string suffix)
-    )
+  val replace: 'a t -> key -> 'a -> unit
+  val mem: 'a t -> key -> bool
+  val iter: 'a t -> (key -> 'a -> unit) -> unit
+  val fold: 
+    'a t -> 'b ->
+    (key -> 'a -> 'b -> 'b) ->  'b
+  val length: 'a t -> int
+  (* val stats: 'a t -> Hashtbl.statistics *)
+  val to_list : 'a t -> (key -> 'a -> 'c) -> 'c list
+  val of_list2: key list -> 'a list -> 'a t
+end
 
-let package_flag_of_package_specs (package_specs : t) 
-    (dirname : string ) : string  = 
-  Spec_set.fold (fun format acc ->
-      Ext_string.inter2 acc (package_flag format dirname )
-    ) package_specs Ext_string.empty
 
-let default_package_specs suffix = 
-  Spec_set.singleton 
-    { format = NodeJS ; in_source = false; suffix  }
 
 
 
-(**
-    [get_list_of_output_js specs "src/hi/hello"]
+end
+module Hash : sig 
+#1 "hash.mli"
 
-*)
-let get_list_of_output_js 
-    (package_specs : Spec_set.t)
-    (output_file_sans_extension : string)
-    = 
-  Spec_set.fold 
-    (fun (spec : spec) acc ->
-        let basename =  
-          Ext_namespace.change_ext_ns_suffix
-             output_file_sans_extension
-             (Ext_js_suffix.to_string spec.suffix)
-        in 
-        (if spec.in_source then Bsb_config.rev_lib_bs_prefix basename
-        else Bsb_config.lib_bs_prefix_of_format spec.format // basename) 
-       :: acc
-    ) package_specs []
 
+module Make (Key : Hashtbl.HashedType) : Hash_gen.S with type key = Key.t
 
-let list_dirs_by
-  (package_specs : Spec_set.t)
-  (f : string -> unit)
-  =  
-  Spec_set.iter (fun (spec : spec)  -> 
-    if not spec.in_source then     
-      f (Bsb_config.top_prefix_of_format spec.format) 
-  ) package_specs 
+end = struct
+#1 "hash.ml"
+# 22 "ext/hash.cppo.ml"
+module Make (Key : Hashtbl.HashedType) = struct 
+  type key = Key.t 
+  type 'a t = (key, 'a)  Hash_gen.t 
+  let key_index (h : _ t ) (key : key) =
+    (Key.hash  key ) land (Array.length h.data - 1)
+  let eq_key = Key.equal   
+
+
+# 33 "ext/hash.cppo.ml"
+type ('a, 'b) bucket = ('a,'b) Hash_gen.bucket
+let create = Hash_gen.create
+let clear = Hash_gen.clear
+let reset = Hash_gen.reset
+let iter = Hash_gen.iter
+let to_list = Hash_gen.to_list
+let fold = Hash_gen.fold
+let length = Hash_gen.length
+(* let stats = Hash_gen.stats *)
+
+
+
+let add (h : _ t) key data =
+  let i = key_index h key in
+  let h_data = h.data in   
+  Array.unsafe_set h_data i (Cons{key; data; next=Array.unsafe_get h_data i});
+  h.size <- h.size + 1;
+  if h.size > Array.length h_data lsl 1 then Hash_gen.resize key_index h
+
+(* after upgrade to 4.04 we should provide an efficient [replace_or_init] *)
+let add_or_update 
+  (h : 'a t) 
+  (key : key) 
+  ~update:(modf : 'a -> 'a) 
+  (default :  'a) : unit =
+  let rec find_bucket (bucketlist : _ bucket) : bool =
+    match bucketlist with
+    | Cons rhs  ->
+      if eq_key rhs.key key then begin rhs.data <- modf rhs.data; false end
+      else find_bucket rhs.next
+    | Empty -> true in
+  let i = key_index h key in 
+  let h_data = h.data in 
+  if find_bucket (Array.unsafe_get h_data i) then
+    begin 
+      Array.unsafe_set h_data i  (Cons{key; data=default; next = Array.unsafe_get h_data i});
+      h.size <- h.size + 1 ;
+      if h.size > Array.length h_data lsl 1 then Hash_gen.resize key_index h 
+    end
+
+let remove (h : _ t ) key =
+  let i = key_index h key in
+  let h_data = h.data in 
+  Hash_gen.remove_bucket h i key ~prec:Empty (Array.unsafe_get h_data i) eq_key
+
+(* for short bucket list, [find_rec is not called ] *)
+let rec find_rec key (bucketlist : _ bucket) = match bucketlist with  
+  | Empty ->
+    raise Not_found
+  | Cons rhs  ->
+    if eq_key key rhs.key then rhs.data else find_rec key rhs.next
+
+let find_exn (h : _ t) key =
+  match Array.unsafe_get h.data (key_index h key) with
+  | Empty -> raise Not_found
+  | Cons rhs  ->
+    if eq_key key rhs.key then rhs.data else
+      match rhs.next with
+      | Empty -> raise Not_found
+      | Cons rhs  ->
+        if eq_key key rhs.key then rhs.data else
+          match rhs.next with
+          | Empty -> raise Not_found
+          | Cons rhs ->
+            if eq_key key rhs.key  then rhs.data else find_rec key rhs.next
+
+let find_opt (h : _ t) key =
+  Hash_gen.small_bucket_opt eq_key key (Array.unsafe_get h.data (key_index h key))
+
+let find_key_opt (h : _ t) key =
+  Hash_gen.small_bucket_key_opt eq_key key (Array.unsafe_get h.data (key_index h key))
   
-type json_map = Ext_json_types.t Map_string.t 
+let find_default (h : _ t) key default = 
+  Hash_gen.small_bucket_default eq_key key default (Array.unsafe_get h.data (key_index h key))
 
-let extract_bs_suffix_exn (map : json_map) : Ext_js_suffix.t =  
-  match map.?(Bsb_build_schemas.suffix) with 
-  | None -> Js  
-  | Some (Str {str; loc}) -> 
-    let s =  Ext_js_suffix.of_string str  in 
-    if s = Unknown_extension then 
-      Bsb_exception.errorf ~loc
-        "expect .bs.js, .js, .cjs, .mjs here"
-    else s     
-  | Some config -> 
-    Bsb_exception.config_error config 
-      "expect a string exteion like \".js\" here"
+let find_all (h : _ t) key =
+  let rec find_in_bucket (bucketlist : _ bucket) = match bucketlist with 
+    | Empty ->
+      []
+    | Cons rhs  ->
+      if eq_key key rhs.key
+      then rhs.data :: find_in_bucket rhs.next
+      else find_in_bucket rhs.next in
+  find_in_bucket (Array.unsafe_get h.data (key_index h key))
 
-let from_map map =  
-  let suffix = extract_bs_suffix_exn map in   
-  match map.?(Bsb_build_schemas.package_specs) with 
-  | Some x ->
-    from_json suffix x 
-  | None ->  default_package_specs suffix
 
+let replace h key data =
+  let i = key_index h key in
+  let h_data = h.data in 
+  let l = Array.unsafe_get h_data i in
+  if Hash_gen.replace_bucket key data l eq_key then 
+    begin 
+      Array.unsafe_set h_data i (Cons{key; data; next=l});
+      h.size <- h.size + 1;
+      if h.size > Array.length h_data lsl 1 then Hash_gen.resize key_index h;
+    end 
 
-end
-module Bsb_package_kind
-= struct
-#1 "bsb_package_kind.ml"
-(* Copyright (C) 2020- Authors of ReScript 
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+let mem (h : _ t) key = 
+  Hash_gen.small_bucket_mem 
+    (Array.unsafe_get h.data (key_index h key))
+    eq_key key 
 
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
-type t = 
-    | Toplevel
-    | Dependency of Bsb_package_specs.t 
-    | Pinned_dependency of Bsb_package_specs.t 
-        (*  This package specs comes from the toplevel to 
-            override the current settings
-        *)
+let of_list2 ks vs = 
+  let len = List.length ks in 
+  let map = create len in 
+  List.iter2 (fun k v -> add map k v) ks vs ; 
+  map
 
+# 143 "ext/hash.cppo.ml"
 end
-module Bsc_warnings
-= struct
-#1 "bsc_warnings.ml"
-(* Copyright (C) 2020- Authors of BuckleScript 
- *
+
+end
+module Bsb_pkg : sig 
+#1 "bsb_pkg.mli"
+
+(* 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
@@ -7395,70 +7431,37 @@ module Bsc_warnings
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-
- *
+ * GNU Lesser General Public License for more details.
+ * 
  * You should have received a copy of the GNU Lesser General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 
+(** [resolve cwd module_name], 
+    [cwd] is current working directory, absolute path
+    Trying to find paths to load [module_name]
+    it is sepcialized for option [-bs-package-include] which requires
+    [npm_package_name/lib/ocaml]
 
-(**
-  See the meanings of the warning codes here: https://caml.inria.fr/pub/docs/manual-ocaml/comp.html#sec281
-
-  - 30 Two labels or constructors of the same name are defined in two mutually recursive types.
-  - 40 Constructor or label name used out of scope.
-
-  - 6 Label omitted in function application.
-  - 7 Method overridden.
-  - 9 Missing fields in a record pattern. (*Not always desired, in some cases need [@@@warning "+9"] *)
-  - 27 Innocuous unused variable: unused variable that is not bound with let nor as, and doesn’t start with an underscore (_) character.
-  - 29 Unescaped end-of-line in a string constant (non-portable code).
-  - 32 .. 39 Unused blabla
-  - 44 Open statement shadows an already defined identifier.
-  - 45 Open statement shadows an already defined label or constructor.
-  - 48 Implicit elimination of optional arguments. https://caml.inria.fr/mantis/view.php?id=6352
-  - 101 (bsb-specific) unsafe polymorphic comparison.
-*) 
-
-
-(*
-  The purpose of default warning set is to make it strict while
-  not annoy user too much
-
-  -4 Fragile pattern matching: matching that will remain complete even if additional con- structors are added to one of the variant types matched.
-  We turn it off since common pattern
-  {[
-    match x with | A -> .. |  _ -> false
-  ]}
+    it relies on [npm_config_prefix] env variable for global npm modules
+*)
 
-  -9 Missing fields in a record pattern.
-  only in some special cases that we need all fields being listed
+(** @raise  when not found *)
+val resolve_bs_package : 
+    cwd:string ->  Bsb_pkg_types.t -> string 
 
-  We encourage people to write code based on type based disambigution
-  40,41,42 are enabled for compatiblity reasons  
-  -40 Constructor or label name used out of scope
-  This is intentional, we should never warn it
-  - 41 Ambiguous constructor or label name.
-  It is turned off since it prevents such cases below:
-  {[
-    type a = A |B 
-    type b = A | B | C
-  ]}
-  - 42 Disambiguated constructor or label name (compatibility warning).
-  
-  - 50 Unexpected documentation comment.
 
-  - 102 Bs_polymorphic_comparison
-*)
-let defaults_w = "+a-4-9-20-40-41-42-50-61-102"
-let defaults_warn_error = "-a+5+6+101+109";;
-(*TODO: add +10*)
+(** used by watcher *)    
+val to_list:    
+  (Bsb_pkg_types.t  ->
+   string ->
+   'a
+  ) -> 'a list
+end = struct
+#1 "bsb_pkg.ml"
 
-end
-module Bsb_warning : sig 
-#1 "bsb_warning.mli"
-(* Copyright (C) 2017 Authors of BuckleScript
+(* Copyright (C) 2017- Authors of BuckleScript
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -7482,30 +7485,208 @@ module Bsb_warning : sig
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
+let (//) = Filename.concat
 
+type t = Bsb_pkg_types.t
 
+(* TODO: be more restrict 
+  [bsconfig.json] does not always make sense, 
+  when resolving [ppx-flags]
+*)
+let make_sub_path (x : t) : string = 
+  Literals.node_modules // Bsb_pkg_types.to_string x
 
-type t
+let node_paths : string list Lazy.t =     
+  lazy (try Ext_string.split (Sys.getenv "NODE_PATH")
+              (if Sys.win32 then ';' else ':')   
+        with _ -> [])
+(** It makes sense to have this function raise, when [bsb] could not resolve a package, it used to mean
+    a failure
+*)
+let check_dir dir =
+  match Sys.file_exists dir with
+  | true -> Some(dir)
+  | false -> None
 
-(** Extra work is need to make merlin happy *)
-val to_merlin_string : t  -> string
+let  resolve_bs_package_aux  ~cwd (pkg : t) =
+  (* First try to resolve recursively from the current working directory  *)
+  let sub_path = make_sub_path pkg   in
+  let rec aux  cwd  =
+    let abs_marker =  cwd // sub_path in
+    if Sys.file_exists abs_marker then abs_marker
+    else
+      let another_cwd = Filename.dirname cwd in (* TODO: may non-terminating when see symlinks *)
+      if String.length another_cwd < String.length cwd then
+        aux    another_cwd
+      else (* To the end try other possiblilities [NODE_PATH]*)
+        (match Ext_list.find_opt (Lazy.force node_paths)
+                 (fun dir -> check_dir (dir // Bsb_pkg_types.to_string pkg))  with
+        | Some(resolved_dir) -> resolved_dir
+        | None -> Bsb_exception.package_not_found ~pkg ~json:None)    
+  in
+   aux cwd 
+    
+    
+    
+    
+    
+
+module Coll = Hash.Make(struct
+  type nonrec t = t 
+  let equal = Bsb_pkg_types.equal
+  let hash (x : t) = Hashtbl.hash x     
+end)
 
 
+let cache : string Coll.t = Coll.create 0
 
-val from_map : Ext_json_types.t Map_string.t -> t 
 
-(** [to_bsb_string not_dev warning]
+let to_list cb  =   
+  Coll.to_list cache  cb 
+  
+(* Some package managers will implement "postinstall" caches, that do not
+ * keep their build artifacts in the local node_modules. Similar to
+ * npm_config_prefix, bs_custom_resolution allows these to specify the
+ * exact location of build cache, but on a per-package basis. Implemented as
+ * environment lookup to avoid invasive changes to bsconfig and mandates. *)
+let custom_resolution = lazy
+  (match Sys.getenv "bs_custom_resolution" with
+  | exception Not_found  -> false
+  | "true"  -> true
+  | _ -> false)
+
+let pkg_name_as_variable package =
+  Bsb_pkg_types.to_string package
+  |> fun s -> Ext_string.split s '@'
+  |> String.concat ""
+  |> fun s -> Ext_string.split s '_'
+  |> String.concat "__"
+  |> fun s -> Ext_string.split s '/'
+  |> String.concat "__slash__"
+  |> fun s -> Ext_string.split s '.'
+  |> String.concat "__dot__"
+  |> fun s -> Ext_string.split s '-'
+  |> String.concat "_"
+
+(** TODO: collect all warnings and print later *)
+let resolve_bs_package ~cwd (package : t) =
+  if Lazy.force custom_resolution then
+  begin
+    Bsb_log.info "@{<info>Using Custom Resolution@}@.";
+    let custom_pkg_loc = pkg_name_as_variable package ^ "__install" in
+    let custom_pkg_location = lazy (Sys.getenv custom_pkg_loc) in
+    match Lazy.force custom_pkg_location with
+    | exception Not_found ->
+        begin
+          Bsb_log.error
+            "@{<error>Custom resolution of package %s does not exist in var %s @}@."
+            (Bsb_pkg_types.to_string package)
+            custom_pkg_loc;
+          Bsb_exception.package_not_found ~pkg:package ~json:None
+        end
+    | path when not (Sys.file_exists path) ->
+        begin
+          Bsb_log.error
+            "@{<error>Custom resolution of package %s does not exist on disk: %s=%s @}@."
+            (Bsb_pkg_types.to_string package)
+            custom_pkg_loc
+            path;
+          Bsb_exception.package_not_found ~pkg:package ~json:None
+        end
+    | path ->
+      begin
+        Bsb_log.info
+          "@{<info>Custom Resolution of package %s in var %s found at %s@}@."
+          (Bsb_pkg_types.to_string package)
+          custom_pkg_loc
+          path;
+        path
+      end
+    end
+  else
+    match Coll.find_opt cache package with
+    | None ->
+      let result = resolve_bs_package_aux ~cwd package in
+      Bsb_log.info "@{<info>Package@} %a -> %s@." Bsb_pkg_types.print package result ;
+      Coll.add cache package result ;
+      result
+    | Some x
+      ->
+      let result = resolve_bs_package_aux ~cwd package in
+      if not (Bsb_real_path.is_same_paths_via_io result x) then
+        begin
+          Bsb_log.warn
+            "@{<warning>Duplicated package:@} %a %s (chosen) vs %s in %s @." 
+              Bsb_pkg_types.print package x result cwd;
+        end;
+      x
+
+
+(** The package does not need to be a bspackage
+    example:
+    {[
+      resolve_npm_package_file ~cwd "reason/refmt";;
+      resolve_npm_package_file ~cwd "reason/refmt/xx/yy"
+    ]}
+    It also returns the path name
+    Note the input [sub_path] is already converted to physical meaning path according to OS
 *)
-val to_bsb_string : 
-  package_kind:Bsb_package_kind.t -> 
-  t  -> 
-  string
+(* let resolve_npm_package_file ~cwd sub_path = *) 
+(*   let rec aux  cwd  =  *)
+(*     let abs_marker =  cwd // Literals.node_modules // sub_path in  *)
+(*     if Sys.file_exists abs_marker then Some abs_marker *)
+(*     else  *)
+(*       let cwd' = Filename.dirname cwd in  *)
+(*       if String.length cwd' < String.length cwd then   *)
+(*         aux cwd'  *)
+(*       else  *)
+(*         try  *)
+(*           let abs_marker =  *)
+(*             Sys.getenv "npm_config_prefix"  *)
+(*             // "lib" // Literals.node_modules // sub_path in *)
+(*           if Sys.file_exists abs_marker *)
+(*           then Some  abs_marker *)
+(*           else None *)
+(*             (\* Bs_exception.error (Bs_package_not_found name) *\) *)
+(*         with  *)
+(*           Not_found -> None *)
+(*           (\* Bs_exception.error (Bs_package_not_found name)           *\) *)
+(*   in *)
+(*   aux cwd *)
 
-val use_default : t
-end = struct
-#1 "bsb_warning.ml"
-(* Copyright (C) 2017 Authors of BuckleScript
- *
+end
+module Ext_js_suffix
+= struct
+#1 "ext_js_suffix.ml"
+type t = 
+  | Js 
+  | Bs_js   
+  | Mjs
+  | Cjs
+  | Unknown_extension
+let to_string (x : t) =   
+  match x with 
+  | Js -> Literals.suffix_js
+  | Bs_js -> Literals.suffix_bs_js  
+  | Mjs -> Literals.suffix_mjs
+  | Cjs -> Literals.suffix_cjs
+  | Unknown_extension -> assert false
+
+
+let of_string (x : string) : t =
+  match () with 
+  | () when x = Literals.suffix_js -> Js 
+  | () when x = Literals.suffix_bs_js -> Bs_js       
+  | () when x = Literals.suffix_mjs -> Mjs
+  | () when x = Literals.suffix_cjs -> Cjs 
+  | _ -> Unknown_extension
+
+
+end
+module Ext_filename : sig 
+#1 "ext_filename.mli"
+(* 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
@@ -7523,195 +7704,74 @@ end = struct
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
- *
+ * 
  * You should have received a copy of the GNU Lesser General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 
-type warning_error =
-  | Warn_error_false
-  (* default [false] to make our changes non-intrusive *)
-  | Warn_error_true
-  | Warn_error_number of string
 
-type t0 = {
-  number : string option;
-  error : warning_error
-}
 
-type nonrec t = t0 option 
 
-let use_default = None
+(* TODO:
+   Change the module name, this code is not really an extension of the standard 
+    library but rather specific to JS Module name convention. 
+*)
 
-let prepare_warning_concat ~(beg : bool) s =
-  let s = Ext_string.trim s in 
-  if s = "" then s 
-  else 
-    match s.[0] with 
-    | '0' .. '9' -> if beg then "-w +" ^ s else "+" ^ s 
-    | 'a' .. 'z' -> 
-      if beg then "-w " ^ s else "-" ^ s 
-    | 'A' .. 'Z' -> 
-      if beg then "-w " ^ s else "+" ^ s  
-    | _ -> 
-      if beg then "-w " ^ s else s
 
-let to_merlin_string x =
-  "-w " ^ Bsc_warnings.defaults_w
-  ^
-  (let customize = (match x with
-       | Some {number =None}
-       | None ->  Ext_string.empty
-       | Some {number = Some x} -> 
-         prepare_warning_concat ~beg:false x 
-     ) in 
-   if customize = "" then customize
-   else customize ^ "-40-42-61") 
-(* see #4406 to avoid user pass A
-   Sync up with {!Warnings.report}
-*)
 
 
-   
-let from_map (m : Ext_json_types.t Map_string.t) =
-  let number_opt = Map_string.find_opt m Bsb_build_schemas.number in
-  let error_opt = Map_string.find_opt m  Bsb_build_schemas.error in
-  match number_opt, error_opt  with
-  | None, None -> None
-  | _, _ ->
-    let error  =
-      match error_opt with
-      | Some (True _) -> Warn_error_true
-      | Some (False _) -> Warn_error_false
-      | Some (Str {str ; })
-        -> Warn_error_number str
-      | Some x -> Bsb_exception.config_error x "expect true/false or string"
-      | None -> Warn_error_false
-      (** To make it less intrusive : warning error has to be enabled*)
-    in
-    let number =
-      match number_opt with
-      | Some (Str { str = number}) -> Some number
-      | None -> None
-      | Some x -> Bsb_exception.config_error x "expect a string"
-    in
-    Some {number; error }
 
+(** An extension module to calculate relative path follow node/npm style. 
+    TODO : this short name will have to change upon renaming the file.
+*)
 
-let to_bsb_string ~(package_kind: Bsb_package_kind.t) warning =
-  match package_kind with 
-  | Toplevel 
-  | Pinned_dependency _ -> 
-    (match warning with
-    | None -> Ext_string.empty
-    | Some warning ->     
-      (match warning.number with
-       | None ->
-         Ext_string.empty
-       | Some x ->
-         prepare_warning_concat ~beg:true x  
-      ) ^
-      (
-        match warning.error with
-        | Warn_error_true ->
-          " -warn-error A"
-        | Warn_error_number y ->
-          " -warn-error " ^ y
-        | Warn_error_false ->
-          Ext_string.empty
-      ))
-  | Dependency _ ->  " -w a" 
-  (* TODO: this is the current default behavior *)
+val is_dir_sep : 
+  char -> bool 
+  
+val maybe_quote:
+  string -> 
+  string
 
-end
-module Bsb_config_types
-= struct
-#1 "bsb_config_types.ml"
-(* 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
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
+val chop_extension_maybe:
+  string -> 
+  string
 
+(* return an empty string if no extension found *)  
+val get_extension_maybe:   
+  string -> 
+  string
 
-type dependency = 
-  {
-    package_name : Bsb_pkg_types.t ; 
-    package_install_path : string ; 
-  }
-type dependencies = dependency list 
 
+val new_extension:  
+  string -> 
+  string -> 
+  string
 
+val chop_all_extensions_maybe:
+  string -> 
+  string  
 
+(* OCaml specific abstraction*)
+val module_name:  
+  string ->
+  string
 
-type reason_react_jsx = 
-  | Jsx_v3
-  (* string option  *)
 
-type refmt = string option
 
-type gentype_config = {
-  path : string (* resolved *)
-}
-type command = string
 
-type ppx = {
-  name : string;
-  args : string list
-}
-type t = 
-  {
-    package_name : string ; 
-    (* [captial-package] *)
-    namespace : string option; 
-    (* CapitalPackage *)
-    external_includes : string list ; 
-    bsc_flags : string list ;
-    ppx_files : ppx list ;
-    pp_file : string option;
-    bs_dependencies : dependencies;
-    bs_dev_dependencies : dependencies;
-    pinned_dependencies : Set_string.t;
-    built_in_dependency : dependency option; 
-    warning : Bsb_warning.t;
-    (*TODO: maybe we should always resolve bs-platform 
-      so that we can calculate correct relative path in 
-      [.merlin]
-    *)
-    refmt : refmt;
-    js_post_build_cmd : string option;
-    package_specs : Bsb_package_specs.t ; 
-    file_groups : Bsb_file_groups.t;
-    files_to_install : Bsb_db.module_info Queue.t ;
-    generate_merlin : bool ; 
-    reason_react_jsx : reason_react_jsx option; (* whether apply PPX transform or not*)
-    generators : command Map_string.t ; 
-    cut_generators : bool; (* note when used as a dev mode, we will always ignore it *)    
-    gentype_config : gentype_config option;
-  }
+type module_info = {
+  module_name : string ;
+  case : bool;
+}   
 
-end
-module Ext_color : sig 
-#1 "ext_color.mli"
+
+
+val as_module:
+  basename:string -> 
+  module_info option
+end = struct
+#1 "ext_filename.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
  * 
  * This program is free software: you can redistribute it and/or modify
@@ -7736,133 +7796,206 @@ module Ext_color : sig
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
-type color 
-  = Black
-  | Red
-  | Green
-  | Yellow
-  | Blue
-  | Magenta
-  | Cyan
-  | White
 
-type style 
-  = FG of color 
-  | BG of color 
-  | Bold
-  | Dim
 
-(** Input is the tag for example `@{<warning>@}` return escape code *)
-val ansi_of_tag : string -> string 
 
-val reset_lit : string
+let is_dir_sep_unix c = c = '/'
+let is_dir_sep_win_cygwin c = 
+  c = '/' || c = '\\' || c = ':'
 
-end = struct
-#1 "ext_color.ml"
-(* 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
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- * 
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
+let is_dir_sep = 
+  if Sys.unix then is_dir_sep_unix else is_dir_sep_win_cygwin
 
+(* reference ninja.cc IsKnownShellSafeCharacter *)
+let maybe_quote ( s : string) = 
+  let noneed_quote = 
+    Ext_string.for_all s (function
+        | '0' .. '9' 
+        | 'a' .. 'z' 
+        | 'A' .. 'Z'
+        | '_' | '+' 
+        | '-' | '.'
+        | '/' 
+        | '@' -> true
+        | _ -> false
+      )  in 
+  if noneed_quote then
+    s
+  else Filename.quote s 
 
 
+let chop_extension_maybe name =
+  let rec search_dot i =
+    if i < 0 || is_dir_sep (String.unsafe_get name i) then name
+    else if String.unsafe_get name i = '.' then String.sub name 0 i
+    else search_dot (i - 1) in
+  search_dot (String.length name - 1)
 
-type color 
-  = Black
-  | Red
-  | Green
-  | Yellow
-  | Blue
-  | Magenta
-  | Cyan
-  | White
+let get_extension_maybe name =   
+  let name_len = String.length name in  
+  let rec search_dot name i name_len =
+    if i < 0 || is_dir_sep (String.unsafe_get name i) then ""
+    else if String.unsafe_get name i = '.' then String.sub name i (name_len - i)
+    else search_dot name (i - 1) name_len in
+  search_dot name (name_len - 1) name_len
 
-type style 
-  = FG of color 
-  | BG of color 
-  | Bold
-  | Dim
+let chop_all_extensions_maybe name =
+  let rec search_dot i last =
+    if i < 0 || is_dir_sep (String.unsafe_get name i) then 
+      (match last with 
+      | None -> name
+      | Some i -> String.sub name 0 i)  
+    else if String.unsafe_get name i = '.' then 
+      search_dot (i - 1) (Some i)
+    else search_dot (i - 1) last in
+  search_dot (String.length name - 1) None
 
 
-(* let ansi_of_color = function
-  | Black -> "0"
-  | Red -> "1"
-  | Green -> "2"
-  | Yellow -> "3"
-  | Blue -> "4"
-  | Magenta -> "5"
-  | Cyan -> "6"
-  | White -> "7" *)
+let new_extension name (ext : string) = 
+  let rec search_dot name i ext =
+    if i < 0 || is_dir_sep (String.unsafe_get name i) then 
+      name ^ ext 
+    else if String.unsafe_get name i = '.' then 
+      let ext_len = String.length ext in
+      let buf = Bytes.create (i + ext_len) in 
+      Bytes.blit_string name 0 buf 0 i;
+      Bytes.blit_string ext 0 buf i ext_len;
+      Bytes.unsafe_to_string buf
+    else search_dot name (i - 1) ext  in
+  search_dot name (String.length name - 1) ext
 
-let code_of_style = function
-  | FG Black -> "30"
-  | FG Red -> "31"
-  | FG Green -> "32"
-  | FG Yellow -> "33"
-  | FG Blue -> "34"
-  | FG Magenta -> "35"
-  | FG Cyan -> "36"
-  | FG White -> "37"
-  
-  | BG Black -> "40"
-  | BG Red -> "41"
-  | BG Green -> "42"
-  | BG Yellow -> "43"
-  | BG Blue -> "44"
-  | BG Magenta -> "45"
-  | BG Cyan -> "46"
-  | BG White -> "47"
 
-  | Bold -> "1"
-  | Dim -> "2"
 
+(** TODO: improve efficiency
+   given a path, calcuate its module name 
+   Note that `ocamlc.opt -c aa.xx.mli` gives `aa.xx.cmi`
+   we can not strip all extensions, otherwise
+   we can not tell the difference between "x.cpp.ml" 
+   and "x.ml"
+*)
+let module_name name = 
+  let rec search_dot i  name =
+    if i < 0  then 
+      Ext_string.capitalize_ascii name
+    else 
+    if String.unsafe_get name i = '.' then 
+      Ext_string.capitalize_sub name i 
+    else 
+      search_dot (i - 1) name in  
+  let name = Filename.basename  name in 
+  let name_len = String.length name in 
+  search_dot (name_len - 1)  name 
 
+type module_info = {
+  module_name : string ;
+  case : bool;
+} 
 
-(** TODO: add more styles later *)
-let style_of_tag s = match s with
-  | "error" -> [Bold; FG Red]
-  | "warning" -> [Bold; FG Magenta]
-  | "info" -> [Bold; FG Yellow]
-  | "dim" -> [Dim]
-  | "filename" -> [FG Cyan]
-  | _ -> []
 
-let ansi_of_tag s = 
-  let l = style_of_tag s in
-  let s =  String.concat ";" (Ext_list.map l  code_of_style) in
-  "\x1b[" ^ s ^ "m"
 
+let rec valid_module_name_aux name off len =
+  if off >= len then true 
+  else 
+    let c = String.unsafe_get name off in 
+    match c with 
+    | 'A'..'Z' | 'a'..'z' | '0'..'9' | '_' | '\'' | '.' | '[' | ']' -> 
+      valid_module_name_aux name (off + 1) len 
+    | _ -> false
 
+type state = 
+  | Invalid
+  | Upper
+  | Lower
 
-let reset_lit = "\x1b[0m" 
+let valid_module_name name len =     
+  if len = 0 then Invalid
+  else 
+    let c = String.unsafe_get name 0 in 
+    match c with 
+    | 'A' .. 'Z'
+      -> 
+      if valid_module_name_aux name 1 len then 
+        Upper
+      else Invalid  
+    | 'a' .. 'z' 
+    | '0' .. '9'
+    | '_'
+    | '[' 
+    | ']'
+      -> 
+      if valid_module_name_aux name 1 len then
+        Lower
+      else Invalid
+    | _ -> Invalid
 
 
+let as_module ~basename =
+  let rec search_dot i  name name_len =
+    if i < 0  then
+      (* Input e.g, [a_b] *)
+      match valid_module_name name name_len with 
+      | Invalid -> None 
+      | Upper ->  Some {module_name = name; case = true }
+      | Lower -> Some {module_name = Ext_string.capitalize_ascii name; case = false}
+    else 
+    if String.unsafe_get name i = '.' then 
+      (*Input e.g, [A_b] *)
+      match valid_module_name  name i with 
+      | Invalid -> None 
+      | Upper -> 
+        Some {module_name = Ext_string.capitalize_sub name i; case = true}
+      | Lower -> 
+        Some {module_name = Ext_string.capitalize_sub name i; case = false}
+    else 
+      search_dot (i - 1) name name_len in  
+  let name_len = String.length basename in       
+  search_dot (name_len - 1)  basename name_len
+    
+end
+module Ext_js_file_kind
+= struct
+#1 "ext_js_file_kind.ml"
+(* Copyright (C) 2020- Authors of BuckleScript
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * In addition to the permissions granted to you by the LGPL, you may combine
+ * or link a "work that uses the Library" with a publicly distributed version
+ * of this file to produce a combined library or application, then distribute
+ * that combined work under the terms of your choosing, with no requirement
+ * to comply with the obligations normally placed on you by section 4 of the
+ * LGPL version 3 (or the corresponding section of a later version of the LGPL
+ * should you choose to use a later version).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
+type case = 
+  | Upper
+  | Little 
 
+type t = {
+  case : case; 
+  suffix : Ext_js_suffix.t;
+}
 
 
+let any_runtime_kind = {
+  case = Little; 
+  suffix = Ext_js_suffix.Js
+}
 end
-module Bsb_log : sig 
-#1 "bsb_log.mli"
-(* Copyright (C) 2017 Authors of BuckleScript
+module Ext_namespace : sig 
+#1 "ext_namespace.mli"
+(* Copyright (C) 2017- Authors of BuckleScript
  * 
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -7887,31 +8020,50 @@ module Bsb_log : sig
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 
-val setup : unit -> unit 
 
-type level = 
-  | Debug
-  | Info 
-  | Warn
-  | Error 
+val try_split_module_name :
+  string -> (string * string ) option
 
-val log_level : level ref
 
-type 'a fmt = Format.formatter -> ('a, Format.formatter, unit) format -> 'a
 
-type 'a log = ('a, Format.formatter, unit) format -> 'a
+(* Note  we have to output uncapitalized file Name, 
+   or at least be consistent, since by reading cmi file on Case insensitive OS, we don't really know it is `list.cmi` or `List.cmi`, so that `require (./list.js)` or `require(./List.js)`
+   relevant issues: #1609, #913  
 
-val verbose : unit -> unit 
-val debug  : 'a log
-val info : 'a log 
-val warn : 'a log 
-val error : 'a log
+   #1933 when removing ns suffix, don't pass the bound
+   of basename
+*)
+val change_ext_ns_suffix :  
+  string -> 
+  string ->
+  string
 
-val info_args : string array -> unit
+
+  
+(** [js_name_of_modulename ~little A-Ns]
+  *)
+val js_name_of_modulename : 
+  string -> 
+  Ext_js_file_kind.case -> 
+  Ext_js_suffix.t ->
+  string
+
+(* TODO handle cases like 
+   '@angular/core'
+   its directory structure is like 
+   {[
+     @angular
+     |-------- core
+   ]}
+*)
+val is_valid_npm_package_name : string -> bool 
+
+val namespace_of_package_name : string -> string
 
 end = struct
-#1 "bsb_log.ml"
-(* Copyright (C) 2017- Authors of BuckleScript
+#1 "ext_namespace.ml"
+
+(* 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
@@ -7937,96 +8089,94 @@ end = struct
 
 
 
-let ninja_ansi_forced = lazy 
-  (try Sys.getenv "NINJA_ANSI_FORCED" with 
-    Not_found  ->""
-  )  
-let color_enabled = lazy (Unix.isatty Unix.stdout)
 
-(* same logic as [ninja.exe] *)
-let get_color_enabled () = 
-  let colorful = 
-    match ninja_ansi_forced with 
-    | lazy "1" -> true     
-    | lazy ("0" | "false") -> false
-    | _ ->
-      Lazy.force color_enabled  in 
-  colorful 
 
+let rec rindex_rec s i  =
+  if i < 0 then i else
+    let char = String.unsafe_get s i in
+    if Ext_filename.is_dir_sep char  then -1 
+    else if char = Literals.ns_sep_char then i 
+    else
+      rindex_rec s (i - 1) 
 
+let change_ext_ns_suffix name ext =
+  let i = rindex_rec name (String.length name - 1)  in 
+  if i < 0 then name ^ ext
+  else String.sub name 0 i ^ ext (* FIXME: micro-optimizaiton*)
 
-let color_functions : Format.formatter_tag_functions = {
-  mark_open_tag = (fun s ->  if get_color_enabled () then  Ext_color.ansi_of_tag s else Ext_string.empty) ;
-  mark_close_tag = (fun _ ->  if get_color_enabled () then Ext_color.reset_lit else Ext_string.empty);
-  print_open_tag = (fun _ -> ());
-  print_close_tag = (fun _ -> ())
-}
-
-(* let set_color ppf =
-  Format.pp_set_formatter_tag_functions ppf color_functions *)
-
-
-let setup () = 
-  begin 
-    Format.pp_set_mark_tags Format.std_formatter true ;
-    Format.pp_set_mark_tags Format.err_formatter true;
-    Format.pp_set_formatter_tag_functions 
-      Format.std_formatter color_functions;
-    Format.pp_set_formatter_tag_functions
-      Format.err_formatter color_functions
-  end
-
-type level = 
-  | Debug
-  | Info 
-  | Warn
-  | Error 
+let try_split_module_name name = 
+  let len = String.length name in 
+  let i = rindex_rec name (len - 1)  in 
+  if i < 0 then None 
+  else 
+    Some (String.sub name (i+1) (len - i - 1),
+          String.sub name 0 i )
 
-let int_of_level (x : level) = 
-  match x with 
-  | Debug -> 0 
-  | Info -> 1 
-  | Warn -> 2 
-  | Error -> 3 
 
-let log_level = ref Warn
 
-let verbose () =
-   log_level := Debug
-let dfprintf level fmt = 
-  if int_of_level level >= int_of_level  !log_level then 
-    Format.fprintf fmt 
-  else Format.ifprintf fmt  
+  
 
-type 'a fmt = 
-  Format.formatter -> ('a, Format.formatter, unit) format -> 'a
-type 'a log = 
-  ('a, Format.formatter, unit) format -> 'a
+let js_name_of_modulename s (case : Ext_js_file_kind.case) suffix : string = 
+  let s = match case with 
+    | Little -> 
+      Ext_string.uncapitalize_ascii s
+    | Upper -> s  in 
+  change_ext_ns_suffix s  (Ext_js_suffix.to_string suffix)
 
-let debug fmt = dfprintf  Debug Format.std_formatter fmt 
-let info fmt = dfprintf Info Format.std_formatter fmt
-let warn fmt = dfprintf Warn Format.err_formatter fmt 
-let error fmt = dfprintf Error Format.err_formatter fmt
+(* https://docs.npmjs.com/files/package.json 
+   Some rules:
+   The name must be less than or equal to 214 characters. This includes the scope for scoped packages.
+   The name can't start with a dot or an underscore.
+   New packages must not have uppercase letters in the name.
+   The name ends up being part of a URL, an argument on the command line, and a folder name. Therefore, the name can't contain any non-URL-safe characters.
+*)
+let is_valid_npm_package_name (s : string) = 
+  let len = String.length s in 
+  len <= 214 && (* magic number forced by npm *)
+  len > 0 &&
+  match String.unsafe_get s 0 with 
+  | 'a' .. 'z' | '@' -> 
+    Ext_string.for_all_from s 1 
+      (fun x -> 
+         match x with 
+         |  'a'..'z' | '0'..'9' | '_' | '-' -> true
+         | _ -> false )
+  | _ -> false 
 
 
-let info_args (args : string array) = 
-  if int_of_level Info >= int_of_level !log_level then 
-    begin
-      for i  = 0 to Array.length args - 1 do
-        Format.pp_print_string Format.std_formatter (Array.unsafe_get args i) ;
-        Format.pp_print_string Format.std_formatter Ext_string.single_space;
-      done ;
-      Format.pp_print_newline Format.std_formatter ()
-    end
-  else ()
-  
+let namespace_of_package_name (s : string) : string = 
+  let len = String.length s in 
+  let buf = Ext_buffer.create len in 
+  let add capital ch = 
+    Ext_buffer.add_char buf 
+      (if capital then 
+         (Char.uppercase_ascii ch)
+       else ch) in    
+  let rec aux capital off len =     
+    if off >= len then ()
+    else 
+      let ch = String.unsafe_get s off in
+      match ch with 
+      | 'a' .. 'z' 
+      | 'A' .. 'Z' 
+      | '0' .. '9'
+      | '_'
+        ->
+        add capital ch ; 
+        aux false (off + 1) len 
+      | '/'
+      | '-' -> 
+        aux true (off + 1) len 
+      | _ -> aux capital (off+1) len
+  in 
+  aux true 0 len ;
+  Ext_buffer.contents buf 
 
 end
-module Bsb_real_path : sig 
-#1 "bsb_real_path.mli"
-
-(* Copyright (C) 2020- Authors of BuckleScript
- *
+module Bsb_package_specs : sig 
+#1 "bsb_package_specs.mli"
+(* Copyright (C) 2017 Authors of BuckleScript
+ * 
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
@@ -8044,90 +8194,41 @@ module Bsb_real_path : sig
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
- *
+ * 
  * You should have received a copy of the GNU Lesser General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
-
-val is_same_paths_via_io : string -> string -> bool 
-
-end = struct
-#1 "bsb_real_path.ml"
-let (//) = Filename.concat
-
-
-
-let normalize_exn (s : string) : string = 
-  let old_cwd = Sys.getcwd () in 
-  Unix.chdir s ;
-  let normalized = Sys.getcwd () in 
-  Unix.chdir old_cwd; 
-  normalized
-
-let real_path p =
-  match Sys.is_directory p with
-  | exception _ ->
-    let rec resolve dir =
-      if Sys.file_exists dir then normalize_exn dir else
-      let parent = Filename.dirname dir in
-      if dir = parent then dir
-      else  (resolve parent) // (Filename.basename dir)
-    in
-    let p =
-      if Filename.is_relative p then (Sys.getcwd ()) // p
-      else p
-    in
-    resolve p
-  | true -> normalize_exn p
-  | false ->
-    let dir = normalize_exn (Filename.dirname p) in
-    match Filename.basename p with
-    | "." -> dir
-    | base -> dir // base
+type t
 
 
-let is_same_paths_via_io a b =
-  if a = b
-  then true
-  else (real_path a) = (real_path b)
 
-end
-module Ext_util : sig 
-#1 "ext_util.mli"
-(* 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
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- * 
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
+val from_map:
+  cwd:string ->
+  Ext_json_types.t Map_string.t -> t 
 
- 
-val power_2_above : int -> int -> int
+val get_list_of_output_js : 
+  t -> 
+  string -> 
+  string list
 
+(**
+  Sample output: {[ -bs-package-output commonjs:lib/js/jscomp/test]}
+*)
+val package_flag_of_package_specs : 
+  t -> 
+  dirname:string -> 
+  string
 
-val stats_to_string : Hashtbl.statistics -> string 
+(* used to ensure each dir does exist *)
+val list_dirs_by :   
+  t -> 
+  (string -> unit) -> 
+  unit
 end = struct
-#1 "ext_util.ml"
-(* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+#1 "bsb_package_specs.ml"
+(* Copyright (C) 2017 Authors of BuckleScript
  * 
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -8151,419 +8252,380 @@ end = struct
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
-(**
-   {[
-     (power_2_above 16 63 = 64)
-       (power_2_above 16 76 = 128)
-   ]}
-*)
-let rec power_2_above x n =
-  if x >= n then x
-  else if x * 2 > Sys.max_array_length then x
-  else power_2_above (x * 2) n
-
-
-let stats_to_string ({num_bindings; num_buckets; max_bucket_length; bucket_histogram} : Hashtbl.statistics) = 
-  Printf.sprintf 
-    "bindings: %d,buckets: %d, longest: %d, hist:[%s]" 
-    num_bindings 
-    num_buckets 
-    max_bucket_length
-    (String.concat "," (Array.to_list (Array.map string_of_int bucket_histogram)))
-end
-module Hash_gen
-= struct
-#1 "hash_gen.ml"
-(***********************************************************************)
-(*                                                                     *)
-(*                                OCaml                                *)
-(*                                                                     *)
-(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
-(*                                                                     *)
-(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
-(*  en Automatique.  All rights reserved.  This file is distributed    *)
-(*  under the terms of the GNU Library General Public License, with    *)
-(*  the special exception on linking described in file ../LICENSE.     *)
-(*                                                                     *)
-(***********************************************************************)
 
-(* Hash tables *)
+let (//) = Ext_path.combine 
 
 
 
+(* TODO: sync up with {!Js_packages_info.module_system}  *)
+type format = Ext_module_system.t = 
+  | NodeJS | Es6 | Es6_global
 
-(* We do dynamic hashing, and resize the table and rehash the elements
-   when buckets become too long. *)
-
-type ('a, 'b) bucket =
-  | Empty
-  | Cons of {
-      mutable key : 'a ; 
-      mutable data : 'b ; 
-      mutable next :  ('a, 'b) bucket
-    }
-
-type ('a, 'b) t =
-  { mutable size: int;                        (* number of entries *)
-    mutable data: ('a, 'b) bucket array;  (* the buckets *)
-    initial_size: int;                        (* initial array size *)
-  }
-
-
-
-let create  initial_size =
-  let s = Ext_util.power_2_above 16 initial_size in
-  { initial_size = s; size = 0; data = Array.make s Empty }
-
-let clear h =
-  h.size <- 0;
-  let len = Array.length h.data in
-  for i = 0 to len - 1 do
-    Array.unsafe_set h.data i  Empty  
-  done
-
-let reset h =
-  h.size <- 0;
-  h.data <- Array.make h.initial_size Empty
-
-
-let length h = h.size
-
-let resize indexfun h =
-  let odata = h.data in
-  let osize = Array.length odata in
-  let nsize = osize * 2 in
-  if nsize < Sys.max_array_length then begin
-    let ndata = Array.make nsize Empty in
-    let ndata_tail = Array.make nsize Empty in 
-    h.data <- ndata;          (* so that indexfun sees the new bucket count *)
-    let rec insert_bucket = function
-        Empty -> ()
-      | Cons {key; next} as cell ->
-        let nidx = indexfun h key in
-        begin match Array.unsafe_get ndata_tail nidx with 
-        | Empty -> 
-          Array.unsafe_set ndata nidx cell
-        | Cons tail ->
-          tail.next <- cell  
-        end;
-        Array.unsafe_set ndata_tail nidx cell;
-        insert_bucket next
-    in
-    for i = 0 to osize - 1 do
-      insert_bucket (Array.unsafe_get odata i)
-    done;
-    for i = 0 to nsize - 1 do 
-      match Array.unsafe_get ndata_tail i with 
-      | Empty -> ()  
-      | Cons tail -> tail.next <- Empty
-    done   
-  end
+type spec = {
+  format : format;
+  in_source : bool;
+  suffix : Ext_js_suffix.t 
+}
 
+(*FIXME: use assoc list instead *)
+module Spec_set = Set.Make( struct type t = spec 
+    let compare = Pervasives.compare 
+  end)
 
+type t = {
+  modules : Spec_set.t;
+  runtime: string option;  
+  (* This has to be resolved as early as possible, since 
+    the path will be inherited in sub projects
+  *)
+}
 
-let iter h f =
-  let rec do_bucket = function
-    | Empty ->
-      ()
-    | Cons l  ->
-      f l.key l.data; do_bucket l.next in
-  let d = h.data in
-  for i = 0 to Array.length d - 1 do
-    do_bucket (Array.unsafe_get d i)
-  done
+let (.?()) = Map_string.find_opt 
 
-let fold h init f =
-  let rec do_bucket b accu =
-    match b with
-      Empty ->
-      accu
-    | Cons l ->
-      do_bucket l.next (f l.key l.data accu) in
-  let d = h.data in
-  let accu = ref init in
-  for i = 0 to Array.length d - 1 do
-    accu := do_bucket (Array.unsafe_get d i) !accu
-  done;
-  !accu
+let bad_module_format_message_exn ~loc format =
+  Bsb_exception.errorf ~loc "package-specs: `%s` isn't a valid output module format. It has to be one of:  %s, %s or %s"
+    format
+    Literals.commonjs
+    Literals.es6
+    Literals.es6_global
 
-let to_list h f =
-  fold h [] (fun k data acc -> f k data :: acc)  
+let supported_format (x : string) loc = 
+  if x = Literals.commonjs then NodeJS
+  else if x = Literals.es6 then Es6
+  else if x = Literals.es6_global then Es6_global
+  else bad_module_format_message_exn ~loc x 
 
+let string_of_format (x : format) =
+  match x with 
+  | NodeJS -> Literals.commonjs
+  | Es6 -> Literals.es6
+  | Es6_global -> Literals.es6_global
 
 
+let rec from_array suffix (arr : Ext_json_types.t array) : Spec_set.t =
+  let spec = ref Spec_set.empty in
+  let has_in_source = ref false in
+  Ext_array.iter arr (fun x ->
+      let result = from_json_single suffix x  in
+      if result.in_source then 
+        (
+          if not !has_in_source then
+            has_in_source:= true
+          else 
+            Bsb_exception.errorf 
+              ~loc:(Ext_json.loc_of x) 
+              "package-specs: we've detected two module formats that are both configured to be in-source." 
+        );
+      spec := Spec_set.add result !spec
+    );
+  !spec
 
-let rec small_bucket_mem (lst : _ bucket) eq key  =
-  match lst with 
-  | Empty -> false 
-  | Cons lst -> 
-    eq  key lst.key ||
-    match lst.next with
-    | Empty -> false 
-    | Cons lst -> 
-      eq key lst.key  || 
-      match lst.next with 
-      | Empty -> false 
-      | Cons lst -> 
-        eq key lst.key  ||
-        small_bucket_mem lst.next eq key 
+(* TODO: FIXME: better API without mutating *)
+and from_json_single suffix (x : Ext_json_types.t) : spec =
+  match x with
+  | Str {str = format; loc } ->    
+      {format = supported_format format loc  ; in_source = false ; suffix }    
+  | Obj {map; loc} ->
+    begin match map .?("module") with
+      | Some(Str {str = format}) ->
+        let in_source = 
+          match map.?(Bsb_build_schemas.in_source) with
+          | Some (True _) -> true
+          | Some _
+          | None -> false
+        in        
+        let suffix = 
+          match map.?("suffix") with
+          | Some (Str {str = suffix; loc}) ->
+            let s = Ext_js_suffix.of_string suffix in 
+            if s = Unknown_extension then 
+              Bsb_exception.errorf ~loc "expect .js,.bs.js,.mjs or .cjs"
+            else  s 
+          | Some _ -> 
+            Bsb_exception.errorf ~loc:(Ext_json.loc_of x) "expect a string field"
+          | None -> suffix in   
+        {format = supported_format format loc ; in_source ; suffix}        
+      | Some _ ->
+        Bsb_exception.errorf ~loc
+          "package-specs: when the configuration is an object, `module` field should be a string, not an array. If you want to pass multiple module specs, try turning package-specs into an array of objects (or strings) instead."      
+      | None ->
+        Bsb_exception.errorf ~loc
+          "package-specs: when the configuration is an object, the `module` field is mandatory."
+    end
+  | _ -> Bsb_exception.errorf ~loc:(Ext_json.loc_of x)
+           "package-specs: we expect either a string or an object."
 
+let  from_json suffix (x : Ext_json_types.t) : Spec_set.t =
+  match x with
+  | Arr {content ; _} -> from_array suffix content
+  | _ -> Spec_set.singleton (from_json_single suffix x )
 
-let rec small_bucket_opt eq key (lst : _ bucket) : _ option =
-  match lst with 
-  | Empty -> None 
-  | Cons lst -> 
-    if eq  key lst.key then Some lst.data else 
-      match lst.next with
-      | Empty -> None 
-      | Cons lst -> 
-        if eq key lst.key then Some lst.data else 
-          match lst.next with 
-          | Empty -> None 
-          | Cons lst -> 
-            if eq key lst.key  then Some lst.data else 
-              small_bucket_opt eq key lst.next
+let bs_package_output = "-bs-package-output"
+[@@@warning "+9"]
+(** Assume input is valid 
+    coordinate with command line flag 
+    {[ -bs-package-output commonjs:lib/js/jscomp/test:.js ]}    
+*)
+let package_flag ({format; in_source; suffix } : spec) dir =
+  Ext_string.inter2
+    bs_package_output 
+    (Ext_string.concat5
+       (string_of_format format)
+       Ext_string.single_colon
+       (if in_source then dir else
+        Bsb_config.top_prefix_of_format format // dir)
+      Ext_string.single_colon  
+      (Ext_js_suffix.to_string suffix)
+    )
 
+(* FIXME: we should adapt it *)    
+let package_flag_of_package_specs (package_specs : t) 
+    ~(dirname : string ) : string  = 
+  let res = Spec_set.fold (fun format acc ->
+      Ext_string.inter2 acc (package_flag format dirname )
+    ) package_specs.modules Ext_string.empty in 
+  match package_specs.runtime with 
+  | None -> res
+  | Some x -> 
+    res ^ " -runtime " ^ x 
+let default_package_specs suffix = 
+  Spec_set.singleton 
+    { format = NodeJS ; in_source = false; suffix  }
 
-let rec small_bucket_key_opt eq key (lst : _ bucket) : _ option =
-  match lst with 
-  | Empty -> None 
-  | Cons {key=k;  next} -> 
-    if eq  key k then Some k else 
-      match next with
-      | Empty -> None 
-      | Cons {key=k; next} -> 
-        if eq key k then Some k else 
-          match next with 
-          | Empty -> None 
-          | Cons {key=k; next} -> 
-            if eq key k  then Some k else 
-              small_bucket_key_opt eq key next
 
 
-let rec small_bucket_default eq key default (lst : _ bucket) =
-  match lst with 
-  | Empty -> default 
-  | Cons lst -> 
-    if eq  key lst.key then  lst.data else 
-      match lst.next with
-      | Empty -> default 
-      | Cons lst -> 
-        if eq key lst.key then  lst.data else 
-          match lst.next with 
-          | Empty -> default 
-          | Cons lst -> 
-            if eq key lst.key  then lst.data else 
-              small_bucket_default eq key default lst.next
+(**
+    [get_list_of_output_js specs "src/hi/hello"]
 
-let rec remove_bucket 
-    h  (i : int)
-    key 
-    ~(prec : _ bucket) 
-    (buck : _ bucket) 
-    eq_key = 
-  match buck with   
-  | Empty ->
-    ()
-  | Cons {key=k; next }  ->
-    if eq_key k key 
-    then begin
-      h.size <- h.size - 1;
-      match prec with
-      | Empty -> Array.unsafe_set h.data i  next
-      | Cons c -> c.next <- next
-    end
-    else remove_bucket h i key ~prec:buck next eq_key
+*)
+let get_list_of_output_js 
+    (package_specs : t)
+    (output_file_sans_extension : string)
+    = 
+  Spec_set.fold 
+    (fun (spec : spec) acc ->
+        let basename =  
+          Ext_namespace.change_ext_ns_suffix
+             output_file_sans_extension
+             (Ext_js_suffix.to_string spec.suffix)
+        in 
+        (if spec.in_source then Bsb_config.rev_lib_bs_prefix basename
+        else Bsb_config.lib_bs_prefix_of_format spec.format // basename) 
+       :: acc
+    ) package_specs.modules []
 
-let rec replace_bucket key data (buck : _ bucket) eq_key = 
-  match buck with   
-  | Empty ->
-    true
-  | Cons slot ->
-    if eq_key slot.key key
-    then (slot.key <- key; slot.data <- data; false)
-    else replace_bucket key data slot.next eq_key
 
-module type S = sig 
-  type key
-  type 'a t
-  val create: int -> 'a t
-  val clear: 'a t -> unit
-  val reset: 'a t -> unit
+let list_dirs_by
+  (package_specs : t)
+  (f : string -> unit)
+  =  
+  Spec_set.iter (fun (spec : spec)  -> 
+    if not spec.in_source then     
+      f (Bsb_config.top_prefix_of_format spec.format) 
+  ) package_specs.modules 
+  
+type json_map = Ext_json_types.t Map_string.t 
 
-  val add: 'a t -> key -> 'a -> unit
-  val add_or_update: 
-    'a t -> 
-    key -> 
-    update:('a -> 'a) -> 
-    'a -> unit 
-  val remove: 'a t -> key -> unit
-  val find_exn: 'a t -> key -> 'a
-  val find_all: 'a t -> key -> 'a list
-  val find_opt: 'a t -> key  -> 'a option
+let extract_bs_suffix_exn (map : json_map) : Ext_js_suffix.t =  
+  match map.?(Bsb_build_schemas.suffix) with 
+  | None -> Js  
+  | Some (Str {str; loc}) -> 
+    let s =  Ext_js_suffix.of_string str  in 
+    if s = Unknown_extension then 
+      Bsb_exception.errorf ~loc
+        "expect .bs.js, .js, .cjs, .mjs here"
+    else s     
+  | Some config -> 
+    Bsb_exception.config_error config 
+      "expect a string exteion like \".js\" here"
 
-  (** return the key found in the hashtbl.
-      Use case: when you find the key existed in hashtbl, 
-      you want to use the one stored in the hashtbl. 
-      (they are semantically equivlanent, but may have other information different) 
-  *)
-  val find_key_opt: 'a t -> key -> key option 
+let from_map ~(cwd:string) map =  
+  let suffix = extract_bs_suffix_exn map in   
+  let modules = match map.?(Bsb_build_schemas.package_specs) with 
+  | Some x ->
+    from_json suffix x 
+  | None ->  default_package_specs suffix in 
+  let runtime = 
+    match map.?(Bsb_build_schemas.external_stdlib) with
+    | None -> None 
+    | Some(Str{str; _}) ->
+       Some (Bsb_pkg.resolve_bs_package ~cwd (Bsb_pkg_types.string_as_package str))
+    | _ -> assert false in   
+  {
+    runtime;  
+    modules 
+  }
 
-  val find_default: 'a t -> key -> 'a -> 'a 
 
-  val replace: 'a t -> key -> 'a -> unit
-  val mem: 'a t -> key -> bool
-  val iter: 'a t -> (key -> 'a -> unit) -> unit
-  val fold: 
-    'a t -> 'b ->
-    (key -> 'a -> 'b -> 'b) ->  'b
-  val length: 'a t -> int
-  (* val stats: 'a t -> Hashtbl.statistics *)
-  val to_list : 'a t -> (key -> 'a -> 'c) -> 'c list
-  val of_list2: key list -> 'a list -> 'a t
 end
+module Bsb_package_kind
+= struct
+#1 "bsb_package_kind.ml"
+(* Copyright (C) 2020- Authors of ReScript 
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * In addition to the permissions granted to you by the LGPL, you may combine
+ * or link a "work that uses the Library" with a publicly distributed version
+ * of this file to produce a combined library or application, then distribute
+ * that combined work under the terms of your choosing, with no requirement
+ * to comply with the obligations normally placed on you by section 4 of the
+ * LGPL version 3 (or the corresponding section of a later version of the LGPL
+ * should you choose to use a later version).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
-
-
+type t = 
+    | Toplevel
+    | Dependency of Bsb_package_specs.t 
+    | Pinned_dependency of Bsb_package_specs.t 
+        (*  This package specs comes from the toplevel to 
+            override the current settings
+        *)
 
 end
-module Hash : sig 
-#1 "hash.mli"
-
-
-module Make (Key : Hashtbl.HashedType) : Hash_gen.S with type key = Key.t
-
-end = struct
-#1 "hash.ml"
-# 22 "ext/hash.cppo.ml"
-module Make (Key : Hashtbl.HashedType) = struct 
-  type key = Key.t 
-  type 'a t = (key, 'a)  Hash_gen.t 
-  let key_index (h : _ t ) (key : key) =
-    (Key.hash  key ) land (Array.length h.data - 1)
-  let eq_key = Key.equal   
-
+module Bsc_warnings
+= struct
+#1 "bsc_warnings.ml"
+(* Copyright (C) 2020- Authors of BuckleScript 
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * In addition to the permissions granted to you by the LGPL, you may combine
+ * or link a "work that uses the Library" with a publicly distributed version
+ * of this file to produce a combined library or application, then distribute
+ * that combined work under the terms of your choosing, with no requirement
+ * to comply with the obligations normally placed on you by section 4 of the
+ * LGPL version 3 (or the corresponding section of a later version of the LGPL
+ * should you choose to use a later version).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 
-# 33 "ext/hash.cppo.ml"
-type ('a, 'b) bucket = ('a,'b) Hash_gen.bucket
-let create = Hash_gen.create
-let clear = Hash_gen.clear
-let reset = Hash_gen.reset
-let iter = Hash_gen.iter
-let to_list = Hash_gen.to_list
-let fold = Hash_gen.fold
-let length = Hash_gen.length
-(* let stats = Hash_gen.stats *)
+ *
+ * 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. *)
 
 
 
-let add (h : _ t) key data =
-  let i = key_index h key in
-  let h_data = h.data in   
-  Array.unsafe_set h_data i (Cons{key; data; next=Array.unsafe_get h_data i});
-  h.size <- h.size + 1;
-  if h.size > Array.length h_data lsl 1 then Hash_gen.resize key_index h
+(**
+  See the meanings of the warning codes here: https://caml.inria.fr/pub/docs/manual-ocaml/comp.html#sec281
 
-(* after upgrade to 4.04 we should provide an efficient [replace_or_init] *)
-let add_or_update 
-  (h : 'a t) 
-  (key : key) 
-  ~update:(modf : 'a -> 'a) 
-  (default :  'a) : unit =
-  let rec find_bucket (bucketlist : _ bucket) : bool =
-    match bucketlist with
-    | Cons rhs  ->
-      if eq_key rhs.key key then begin rhs.data <- modf rhs.data; false end
-      else find_bucket rhs.next
-    | Empty -> true in
-  let i = key_index h key in 
-  let h_data = h.data in 
-  if find_bucket (Array.unsafe_get h_data i) then
-    begin 
-      Array.unsafe_set h_data i  (Cons{key; data=default; next = Array.unsafe_get h_data i});
-      h.size <- h.size + 1 ;
-      if h.size > Array.length h_data lsl 1 then Hash_gen.resize key_index h 
-    end
+  - 30 Two labels or constructors of the same name are defined in two mutually recursive types.
+  - 40 Constructor or label name used out of scope.
 
-let remove (h : _ t ) key =
-  let i = key_index h key in
-  let h_data = h.data in 
-  Hash_gen.remove_bucket h i key ~prec:Empty (Array.unsafe_get h_data i) eq_key
+  - 6 Label omitted in function application.
+  - 7 Method overridden.
+  - 9 Missing fields in a record pattern. (*Not always desired, in some cases need [@@@warning "+9"] *)
+  - 27 Innocuous unused variable: unused variable that is not bound with let nor as, and doesn’t start with an underscore (_) character.
+  - 29 Unescaped end-of-line in a string constant (non-portable code).
+  - 32 .. 39 Unused blabla
+  - 44 Open statement shadows an already defined identifier.
+  - 45 Open statement shadows an already defined label or constructor.
+  - 48 Implicit elimination of optional arguments. https://caml.inria.fr/mantis/view.php?id=6352
+  - 101 (bsb-specific) unsafe polymorphic comparison.
+*) 
 
-(* for short bucket list, [find_rec is not called ] *)
-let rec find_rec key (bucketlist : _ bucket) = match bucketlist with  
-  | Empty ->
-    raise Not_found
-  | Cons rhs  ->
-    if eq_key key rhs.key then rhs.data else find_rec key rhs.next
 
-let find_exn (h : _ t) key =
-  match Array.unsafe_get h.data (key_index h key) with
-  | Empty -> raise Not_found
-  | Cons rhs  ->
-    if eq_key key rhs.key then rhs.data else
-      match rhs.next with
-      | Empty -> raise Not_found
-      | Cons rhs  ->
-        if eq_key key rhs.key then rhs.data else
-          match rhs.next with
-          | Empty -> raise Not_found
-          | Cons rhs ->
-            if eq_key key rhs.key  then rhs.data else find_rec key rhs.next
+(*
+  The purpose of default warning set is to make it strict while
+  not annoy user too much
 
-let find_opt (h : _ t) key =
-  Hash_gen.small_bucket_opt eq_key key (Array.unsafe_get h.data (key_index h key))
+  -4 Fragile pattern matching: matching that will remain complete even if additional con- structors are added to one of the variant types matched.
+  We turn it off since common pattern
+  {[
+    match x with | A -> .. |  _ -> false
+  ]}
 
-let find_key_opt (h : _ t) key =
-  Hash_gen.small_bucket_key_opt eq_key key (Array.unsafe_get h.data (key_index h key))
+  -9 Missing fields in a record pattern.
+  only in some special cases that we need all fields being listed
+
+  We encourage people to write code based on type based disambigution
+  40,41,42 are enabled for compatiblity reasons  
+  -40 Constructor or label name used out of scope
+  This is intentional, we should never warn it
+  - 41 Ambiguous constructor or label name.
+  It is turned off since it prevents such cases below:
+  {[
+    type a = A |B 
+    type b = A | B | C
+  ]}
+  - 42 Disambiguated constructor or label name (compatibility warning).
   
-let find_default (h : _ t) key default = 
-  Hash_gen.small_bucket_default eq_key key default (Array.unsafe_get h.data (key_index h key))
+  - 50 Unexpected documentation comment.
 
-let find_all (h : _ t) key =
-  let rec find_in_bucket (bucketlist : _ bucket) = match bucketlist with 
-    | Empty ->
-      []
-    | Cons rhs  ->
-      if eq_key key rhs.key
-      then rhs.data :: find_in_bucket rhs.next
-      else find_in_bucket rhs.next in
-  find_in_bucket (Array.unsafe_get h.data (key_index h key))
+  - 102 Bs_polymorphic_comparison
+*)
+let defaults_w = "+a-4-9-20-40-41-42-50-61-102"
+let defaults_warn_error = "-a+5+6+101+109";;
+(*TODO: add +10*)
+
+end
+module Bsb_warning : sig 
+#1 "bsb_warning.mli"
+(* Copyright (C) 2017 Authors of BuckleScript
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * In addition to the permissions granted to you by the LGPL, you may combine
+ * or link a "work that uses the Library" with a publicly distributed version
+ * of this file to produce a combined library or application, then distribute
+ * that combined work under the terms of your choosing, with no requirement
+ * to comply with the obligations normally placed on you by section 4 of the
+ * LGPL version 3 (or the corresponding section of a later version of the LGPL
+ * should you choose to use a later version).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 
-let replace h key data =
-  let i = key_index h key in
-  let h_data = h.data in 
-  let l = Array.unsafe_get h_data i in
-  if Hash_gen.replace_bucket key data l eq_key then 
-    begin 
-      Array.unsafe_set h_data i (Cons{key; data; next=l});
-      h.size <- h.size + 1;
-      if h.size > Array.length h_data lsl 1 then Hash_gen.resize key_index h;
-    end 
 
-let mem (h : _ t) key = 
-  Hash_gen.small_bucket_mem 
-    (Array.unsafe_get h.data (key_index h key))
-    eq_key key 
 
+type t
 
-let of_list2 ks vs = 
-  let len = List.length ks in 
-  let map = create len in 
-  List.iter2 (fun k v -> add map k v) ks vs ; 
-  map
+(** Extra work is need to make merlin happy *)
+val to_merlin_string : t  -> string
 
-# 143 "ext/hash.cppo.ml"
-end
 
-end
-module Bsb_pkg : sig 
-#1 "bsb_pkg.mli"
 
-(* Copyright (C) 2015-2016 Bloomberg Finance L.P.
- * 
+val from_map : Ext_json_types.t Map_string.t -> t 
+
+(** [to_bsb_string not_dev warning]
+*)
+val to_bsb_string : 
+  package_kind:Bsb_package_kind.t -> 
+  t  -> 
+  string
+
+val use_default : t
+end = struct
+#1 "bsb_warning.ml"
+(* Copyright (C) 2017 Authors of BuckleScript
+ *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
@@ -8581,35 +8643,112 @@ module Bsb_pkg : sig
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU Lesser General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 
-(** [resolve cwd module_name], 
-    [cwd] is current working directory, absolute path
-    Trying to find paths to load [module_name]
-    it is sepcialized for option [-bs-package-include] which requires
-    [npm_package_name/lib/ocaml]
+type warning_error =
+  | Warn_error_false
+  (* default [false] to make our changes non-intrusive *)
+  | Warn_error_true
+  | Warn_error_number of string
 
-    it relies on [npm_config_prefix] env variable for global npm modules
-*)
+type t0 = {
+  number : string option;
+  error : warning_error
+}
 
-(** @raise  when not found *)
-val resolve_bs_package : 
-    cwd:string ->  Bsb_pkg_types.t -> string 
+type nonrec t = t0 option 
 
+let use_default = None
 
-val to_list:    
-  (Bsb_pkg_types.t  ->
-   string ->
-   'a
-  ) -> 'a list
-end = struct
-#1 "bsb_pkg.ml"
+let prepare_warning_concat ~(beg : bool) s =
+  let s = Ext_string.trim s in 
+  if s = "" then s 
+  else 
+    match s.[0] with 
+    | '0' .. '9' -> if beg then "-w +" ^ s else "+" ^ s 
+    | 'a' .. 'z' -> 
+      if beg then "-w " ^ s else "-" ^ s 
+    | 'A' .. 'Z' -> 
+      if beg then "-w " ^ s else "+" ^ s  
+    | _ -> 
+      if beg then "-w " ^ s else s
+
+let to_merlin_string x =
+  "-w " ^ Bsc_warnings.defaults_w
+  ^
+  (let customize = (match x with
+       | Some {number =None}
+       | None ->  Ext_string.empty
+       | Some {number = Some x} -> 
+         prepare_warning_concat ~beg:false x 
+     ) in 
+   if customize = "" then customize
+   else customize ^ "-40-42-61") 
+(* see #4406 to avoid user pass A
+   Sync up with {!Warnings.report}
+*)
+
+
+   
+let from_map (m : Ext_json_types.t Map_string.t) =
+  let number_opt = Map_string.find_opt m Bsb_build_schemas.number in
+  let error_opt = Map_string.find_opt m  Bsb_build_schemas.error in
+  match number_opt, error_opt  with
+  | None, None -> None
+  | _, _ ->
+    let error  =
+      match error_opt with
+      | Some (True _) -> Warn_error_true
+      | Some (False _) -> Warn_error_false
+      | Some (Str {str ; })
+        -> Warn_error_number str
+      | Some x -> Bsb_exception.config_error x "expect true/false or string"
+      | None -> Warn_error_false
+      (** To make it less intrusive : warning error has to be enabled*)
+    in
+    let number =
+      match number_opt with
+      | Some (Str { str = number}) -> Some number
+      | None -> None
+      | Some x -> Bsb_exception.config_error x "expect a string"
+    in
+    Some {number; error }
 
-(* Copyright (C) 2017- Authors of BuckleScript
+
+let to_bsb_string ~(package_kind: Bsb_package_kind.t) warning =
+  match package_kind with 
+  | Toplevel 
+  | Pinned_dependency _ -> 
+    (match warning with
+    | None -> Ext_string.empty
+    | Some warning ->     
+      (match warning.number with
+       | None ->
+         Ext_string.empty
+       | Some x ->
+         prepare_warning_concat ~beg:true x  
+      ) ^
+      (
+        match warning.error with
+        | Warn_error_true ->
+          " -warn-error A"
+        | Warn_error_number y ->
+          " -warn-error " ^ y
+        | Warn_error_false ->
+          Ext_string.empty
+      ))
+  | Dependency _ ->  " -w a" 
+  (* TODO: this is the current default behavior *)
+
+end
+module Bsb_config_types
+= struct
+#1 "bsb_config_types.ml"
+(* 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
@@ -8633,174 +8772,62 @@ end = struct
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
-let (//) = Filename.concat
-
-type t = Bsb_pkg_types.t
-
-(* TODO: be more restrict 
-  [bsconfig.json] does not always make sense, 
-  when resolving [ppx-flags]
-*)
-let make_sub_path (x : t) : string = 
-  Literals.node_modules // Bsb_pkg_types.to_string x
-
-let node_paths : string list Lazy.t =     
-  lazy (try Ext_string.split (Sys.getenv "NODE_PATH")
-              (if Sys.win32 then ';' else ':')   
-        with _ -> [])
-(** It makes sense to have this function raise, when [bsb] could not resolve a package, it used to mean
-    a failure
-*)
-let check_dir dir =
-  match Sys.file_exists dir with
-  | true -> Some(dir)
-  | false -> None
-
-let  resolve_bs_package_aux  ~cwd (pkg : t) =
-  (* First try to resolve recursively from the current working directory  *)
-  let sub_path = make_sub_path pkg   in
-  let rec aux  cwd  =
-    let abs_marker =  cwd // sub_path in
-    if Sys.file_exists abs_marker then abs_marker
-    else
-      let another_cwd = Filename.dirname cwd in (* TODO: may non-terminating when see symlinks *)
-      if String.length another_cwd < String.length cwd then
-        aux    another_cwd
-      else (* To the end try other possiblilities [NODE_PATH]*)
-        (match Ext_list.find_opt (Lazy.force node_paths)
-                 (fun dir -> check_dir (dir // Bsb_pkg_types.to_string pkg))  with
-        | Some(resolved_dir) -> resolved_dir
-        | None -> Bsb_exception.package_not_found ~pkg ~json:None)    
-  in
-   aux cwd 
-    
-    
-    
-    
-    
-
-module Coll = Hash.Make(struct
-  type nonrec t = t 
-  let equal = Bsb_pkg_types.equal
-  let hash (x : t) = Hashtbl.hash x     
-end)
 
+type dependency = 
+  {
+    package_name : Bsb_pkg_types.t ; 
+    package_install_path : string ; 
+  }
+type dependencies = dependency list 
 
-let cache : string Coll.t = Coll.create 0
 
 
-let to_list cb  =   
-  Coll.to_list cache  cb 
-  
-(* Some package managers will implement "postinstall" caches, that do not
- * keep their build artifacts in the local node_modules. Similar to
- * npm_config_prefix, bs_custom_resolution allows these to specify the
- * exact location of build cache, but on a per-package basis. Implemented as
- * environment lookup to avoid invasive changes to bsconfig and mandates. *)
-let custom_resolution = lazy
-  (match Sys.getenv "bs_custom_resolution" with
-  | exception Not_found  -> false
-  | "true"  -> true
-  | _ -> false)
 
-let pkg_name_as_variable package =
-  Bsb_pkg_types.to_string package
-  |> fun s -> Ext_string.split s '@'
-  |> String.concat ""
-  |> fun s -> Ext_string.split s '_'
-  |> String.concat "__"
-  |> fun s -> Ext_string.split s '/'
-  |> String.concat "__slash__"
-  |> fun s -> Ext_string.split s '.'
-  |> String.concat "__dot__"
-  |> fun s -> Ext_string.split s '-'
-  |> String.concat "_"
+type reason_react_jsx = 
+  | Jsx_v3
+  (* string option  *)
 
-(** TODO: collect all warnings and print later *)
-let resolve_bs_package ~cwd (package : t) =
-  if Lazy.force custom_resolution then
-  begin
-    Bsb_log.info "@{<info>Using Custom Resolution@}@.";
-    let custom_pkg_loc = pkg_name_as_variable package ^ "__install" in
-    let custom_pkg_location = lazy (Sys.getenv custom_pkg_loc) in
-    match Lazy.force custom_pkg_location with
-    | exception Not_found ->
-        begin
-          Bsb_log.error
-            "@{<error>Custom resolution of package %s does not exist in var %s @}@."
-            (Bsb_pkg_types.to_string package)
-            custom_pkg_loc;
-          Bsb_exception.package_not_found ~pkg:package ~json:None
-        end
-    | path when not (Sys.file_exists path) ->
-        begin
-          Bsb_log.error
-            "@{<error>Custom resolution of package %s does not exist on disk: %s=%s @}@."
-            (Bsb_pkg_types.to_string package)
-            custom_pkg_loc
-            path;
-          Bsb_exception.package_not_found ~pkg:package ~json:None
-        end
-    | path ->
-      begin
-        Bsb_log.info
-          "@{<info>Custom Resolution of package %s in var %s found at %s@}@."
-          (Bsb_pkg_types.to_string package)
-          custom_pkg_loc
-          path;
-        path
-      end
-    end
-  else
-    match Coll.find_opt cache package with
-    | None ->
-      let result = resolve_bs_package_aux ~cwd package in
-      Bsb_log.info "@{<info>Package@} %a -> %s@." Bsb_pkg_types.print package result ;
-      Coll.add cache package result ;
-      result
-    | Some x
-      ->
-      let result = resolve_bs_package_aux ~cwd package in
-      if not (Bsb_real_path.is_same_paths_via_io result x) then
-        begin
-          Bsb_log.warn
-            "@{<warning>Duplicated package:@} %a %s (chosen) vs %s in %s @." 
-              Bsb_pkg_types.print package x result cwd;
-        end;
-      x
+type refmt = string option
 
+type gentype_config = {
+  path : string (* resolved *)
+}
+type command = string
 
-(** The package does not need to be a bspackage
-    example:
-    {[
-      resolve_npm_package_file ~cwd "reason/refmt";;
-      resolve_npm_package_file ~cwd "reason/refmt/xx/yy"
-    ]}
-    It also returns the path name
-    Note the input [sub_path] is already converted to physical meaning path according to OS
-*)
-(* let resolve_npm_package_file ~cwd sub_path = *) 
-(*   let rec aux  cwd  =  *)
-(*     let abs_marker =  cwd // Literals.node_modules // sub_path in  *)
-(*     if Sys.file_exists abs_marker then Some abs_marker *)
-(*     else  *)
-(*       let cwd' = Filename.dirname cwd in  *)
-(*       if String.length cwd' < String.length cwd then   *)
-(*         aux cwd'  *)
-(*       else  *)
-(*         try  *)
-(*           let abs_marker =  *)
-(*             Sys.getenv "npm_config_prefix"  *)
-(*             // "lib" // Literals.node_modules // sub_path in *)
-(*           if Sys.file_exists abs_marker *)
-(*           then Some  abs_marker *)
-(*           else None *)
-(*             (\* Bs_exception.error (Bs_package_not_found name) *\) *)
-(*         with  *)
-(*           Not_found -> None *)
-(*           (\* Bs_exception.error (Bs_package_not_found name)           *\) *)
-(*   in *)
-(*   aux cwd *)
+type ppx = {
+  name : string;
+  args : string list
+}
+type t = 
+  {
+    package_name : string ; 
+    (* [captial-package] *)
+    namespace : string option; 
+    (* CapitalPackage *)
+    external_includes : string list ; 
+    bsc_flags : string list ;
+    ppx_files : ppx list ;
+    pp_file : string option;
+    bs_dependencies : dependencies;
+    bs_dev_dependencies : dependencies;
+    pinned_dependencies : Set_string.t;
+    built_in_dependency : bool; 
+    warning : Bsb_warning.t;
+    (*TODO: maybe we should always resolve bs-platform 
+      so that we can calculate correct relative path in 
+      [.merlin]
+    *)
+    refmt : refmt;
+    js_post_build_cmd : string option;
+    package_specs : Bsb_package_specs.t ; 
+    file_groups : Bsb_file_groups.t;
+    files_to_install : Bsb_db.module_info Queue.t ;
+    generate_merlin : bool ; 
+    reason_react_jsx : reason_react_jsx option; (* whether apply PPX transform or not*)
+    generators : command Map_string.t ; 
+    cut_generators : bool; (* note when used as a dev mode, we will always ignore it *)    
+    gentype_config : gentype_config option;
+  }
 
 end
 module Ext_json_parse : sig 
@@ -11119,48 +11146,26 @@ let extract_package_name_and_namespace
     - the running bsb and vendoring bsb is the same
     - the running bsb need delete stale build artifacts
       (kinda check npm upgrade)
-*)
-let check_version_exit (map : json_map) stdlib_path =   
-  match Map_string.find_exn map Bsb_build_schemas.version with 
-  | Str {str } -> 
-    if str <> Bs_version.version then 
-      begin
-        Format.fprintf Format.err_formatter
-          "@{<error>bs-platform version mismatch@} Running bsb @{<info>%s@} (%s) vs vendored @{<info>%s@} (%s)@."
-          Bs_version.version
-          (Filename.dirname (Filename.dirname Sys.executable_name))
-          str
-          stdlib_path 
-        ;
-        exit 2
-      end
-  | _ -> assert false
 
-let check_stdlib (map : json_map) cwd (*built_in_package*) =  
+      Note if the setup is correct: 
+      the running compiler and node_modules/bs-platform
+      should be the same version, 
+      The exact check is that the running compiler should have a 
+      compatible runtime version installed, the location of the
+      compiler is actually not relevant.
+      We disable the check temporarily
+      e.g,
+      ```
+      bsc -runtime runtime_dir@version
+      ```
+*)  
+let check_stdlib (map : json_map) (*built_in_package*) : bool =  
   match map.?( Bsb_build_schemas.use_stdlib) with      
-  | Some (False _) -> None    
+  | Some (False _) -> false
   | None 
-  | Some _ ->
-    begin
-      let current_package : Bsb_pkg_types.t = Global !Bs_version.package_name in  
-      if Sys.getenv_opt "RES_SKIP_STDLIB_CHECK" = None then begin 
-        let stdlib_path = 
-          Bsb_pkg.resolve_bs_package ~cwd current_package in 
-        let json_spec = 
-          Ext_json_parse.parse_json_from_file
-            (* No exn raised: stdlib  has package.json *)
-            (Filename.concat stdlib_path Literals.package_json) in 
-        match json_spec with 
-        | Obj {map}  -> 
-          check_version_exit map stdlib_path;
-
-        | _ -> assert false
-      end;
-      Some {
-        Bsb_config_types.package_name = current_package;
-        package_install_path = Filename.dirname Bsb_global_paths.bsc_dir // Bsb_config.lib_ocaml;
-      }
-    end
+  | Some _ ->    
+    true
+
 
 
 
@@ -11384,7 +11389,7 @@ let interpret_json
          array from the bsconfig and set the backend_ref to the first entry, if any. *)
 
     (* The default situation is empty *)
-    let built_in_package = check_stdlib map per_proj_dir in
+    let built_in_package : bool = check_stdlib map  in
     
     let pp_flags : string option = 
       extract_string map Bsb_build_schemas.pp_flags (fun p -> 
@@ -11439,7 +11444,7 @@ let interpret_json
           js_post_build_cmd = (extract_js_post_build map per_proj_dir);
           package_specs = 
             (match package_kind with 
-             | Toplevel ->  Bsb_package_specs.from_map map                
+             | Toplevel ->  Bsb_package_specs.from_map ~cwd:per_proj_dir map                
              | Pinned_dependency x
              | Dependency x -> x);          
           file_groups = groups; 
@@ -11463,7 +11468,7 @@ let package_specs_from_bsconfig () =
   let json = Ext_json_parse.parse_json_from_file Literals.bsconfig_json in
   begin match json with
     | Obj {map} ->
-      Bsb_package_specs.from_map map,
+      Bsb_package_specs.from_map ~cwd:Bsb_global_paths.cwd map,
       extract_pinned_dependencies map
     | _ -> assert false
   end
@@ -12014,11 +12019,13 @@ let merlin_file_gen ~per_proj_dir:(per_proj_dir:string)
         Buffer.add_string buffer merlin_b;
         Buffer.add_string buffer path ;
       );      
-    Ext_option.iter built_in_dependency (fun package -> 
-        let path = package.package_install_path in 
-        Buffer.add_string buffer (merlin_s ^ path );
-        Buffer.add_string buffer (merlin_b ^ path)                      
-      );
+    if built_in_dependency then (
+      let path = 
+        (Filename.dirname Bsb_global_paths.bsc_dir) 
+        // "lib" //"ocaml" in 
+      Buffer.add_string buffer (merlin_s ^ path );
+      Buffer.add_string buffer (merlin_b ^ path)                      
+    );
     let bsc_string_flag = bsc_flg_to_merlin_ocamlc_flg bsc_flags in 
     Buffer.add_string buffer bsc_string_flag ;
     Buffer.add_string buffer (warning_to_merlin_flg  warning); 
@@ -12940,7 +12947,8 @@ let make_custom_rules
     if read_cmi <> `is_cmi then begin 
       Ext_buffer.add_string buf " -bs-package-name ";
       Ext_buffer.add_string buf package_name;
-      Ext_buffer.add_string buf (Bsb_package_specs.package_flag_of_package_specs package_specs "$in_d")
+      Ext_buffer.add_string buf 
+        (Bsb_package_specs.package_flag_of_package_specs package_specs ~dirname:"$in_d")
     end;
     begin match bs_dependencies, bs_dev_dependencies with 
     | [], [] -> ()
@@ -13757,7 +13765,7 @@ let output_ninja_and_namespace_map
       ~gentype_config
       ~has_postbuild:js_post_build_cmd 
       ~pp_file
-      ~has_builtin:(built_in_dependency <> None)
+      ~has_builtin:built_in_dependency 
       ~reason_react_jsx
       ~package_specs
       ~namespace
diff --git a/lib/4.06.1/unstable/all_ounit_tests.ml b/lib/4.06.1/unstable/all_ounit_tests.ml
index 2e3e0b94a5..10bb490351 100644
--- a/lib/4.06.1/unstable/all_ounit_tests.ml
+++ b/lib/4.06.1/unstable/all_ounit_tests.ml
@@ -7500,7 +7500,10 @@ let string_as_package (s : string) : t =
   if v = '@' then 
     let scope_id = 
         Ext_string.no_slash_idx s in 
-    assert (scope_id > 0);
+    assert (scope_id > 0); 
+    (* better-eror message for invalid scope package:
+      @rescript/std
+    *)
     Scope(
       String.sub s (scope_id + 1) (len - scope_id - 1),
       String.sub s 0 scope_id
diff --git a/lib/4.06.1/unstable/bspack.ml b/lib/4.06.1/unstable/bspack.ml
index c632307ae1..a212d52572 100644
--- a/lib/4.06.1/unstable/bspack.ml
+++ b/lib/4.06.1/unstable/bspack.ml
@@ -11956,7 +11956,7 @@ val no_export: bool ref
 val as_ppx : bool ref 
 
 val mono_empty_array : bool ref
-
+val customize_runtime : string option ref 
 end = struct
 #1 "js_config.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
@@ -12051,7 +12051,7 @@ let as_ppx = ref false
 
 let mono_empty_array = ref true
 
-
+let customize_runtime = ref None 
 end
 module Map_gen : sig 
 #1 "map_gen.mli"
diff --git a/lib/4.06.1/unstable/js_compiler.ml b/lib/4.06.1/unstable/js_compiler.ml
index 730c8a208f..0af1f973a7 100644
--- a/lib/4.06.1/unstable/js_compiler.ml
+++ b/lib/4.06.1/unstable/js_compiler.ml
@@ -17892,7 +17892,7 @@ val no_export: bool ref
 val as_ppx : bool ref 
 
 val mono_empty_array : bool ref
-
+val customize_runtime : string option ref 
 end = struct
 #1 "js_config.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
@@ -17987,7 +17987,7 @@ let as_ppx = ref false
 
 let mono_empty_array = ref true
 
-
+let customize_runtime = ref None 
 end
 module Bs_cmi_load
 = struct
@@ -92280,7 +92280,19 @@ let runtime_test_package_specs : t = {
   name = Pkg_runtime; 
   module_systems = []
 }
-let same_package_by_name (x : t) (y : t) = x.name = y.name 
+
+let same_package_by_name (x : t) (y : t) =
+  match x.name with 
+  | Pkg_empty -> 
+    y.name = Pkg_empty
+  | Pkg_runtime -> 
+    y.name = Pkg_runtime 
+  | Pkg_normal s -> 
+    begin match y.name with 
+    | Pkg_normal y -> s = y
+    | Pkg_empty | Pkg_runtime -> false
+    end
+   
 
 let is_runtime_package (x : t) = 
     x.name = Pkg_runtime
@@ -98653,7 +98665,12 @@ let get_runtime_module_path
           (*Invariant: the package path to bs-platform, it is used to 
             calculate relative js path
           *)
-          ((Filename.dirname (Filename.dirname Sys.executable_name)) // dep_path // js_file)  
+          (match !Js_config.customize_runtime with 
+           | None ->
+             ((Filename.dirname (Filename.dirname Sys.executable_name)) // dep_path // js_file)
+           | Some path -> 
+             path //dep_path // js_file 
+          )  
 
 
 
@@ -98715,6 +98732,9 @@ let string_of_module_id
                   which is guaranteed by [-bs-package-output]
               *)
           else  
+          if Js_packages_info.is_runtime_package dep_package_info then 
+            get_runtime_module_path dep_module_id current_package_info module_system
+          else 
             begin match module_system with 
               | NodeJS | Es6 -> 
                 dep_pkg.pkg_rel_path // js_file
diff --git a/lib/4.06.1/unstable/js_refmt_compiler.ml b/lib/4.06.1/unstable/js_refmt_compiler.ml
index 5d7c1e908d..d2d8c3ecc3 100644
--- a/lib/4.06.1/unstable/js_refmt_compiler.ml
+++ b/lib/4.06.1/unstable/js_refmt_compiler.ml
@@ -17892,7 +17892,7 @@ val no_export: bool ref
 val as_ppx : bool ref 
 
 val mono_empty_array : bool ref
-
+val customize_runtime : string option ref 
 end = struct
 #1 "js_config.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
@@ -17987,7 +17987,7 @@ let as_ppx = ref false
 
 let mono_empty_array = ref true
 
-
+let customize_runtime = ref None 
 end
 module Bs_cmi_load
 = struct
@@ -92280,7 +92280,19 @@ let runtime_test_package_specs : t = {
   name = Pkg_runtime; 
   module_systems = []
 }
-let same_package_by_name (x : t) (y : t) = x.name = y.name 
+
+let same_package_by_name (x : t) (y : t) =
+  match x.name with 
+  | Pkg_empty -> 
+    y.name = Pkg_empty
+  | Pkg_runtime -> 
+    y.name = Pkg_runtime 
+  | Pkg_normal s -> 
+    begin match y.name with 
+    | Pkg_normal y -> s = y
+    | Pkg_empty | Pkg_runtime -> false
+    end
+   
 
 let is_runtime_package (x : t) = 
     x.name = Pkg_runtime
@@ -98653,7 +98665,12 @@ let get_runtime_module_path
           (*Invariant: the package path to bs-platform, it is used to 
             calculate relative js path
           *)
-          ((Filename.dirname (Filename.dirname Sys.executable_name)) // dep_path // js_file)  
+          (match !Js_config.customize_runtime with 
+           | None ->
+             ((Filename.dirname (Filename.dirname Sys.executable_name)) // dep_path // js_file)
+           | Some path -> 
+             path //dep_path // js_file 
+          )  
 
 
 
@@ -98715,6 +98732,9 @@ let string_of_module_id
                   which is guaranteed by [-bs-package-output]
               *)
           else  
+          if Js_packages_info.is_runtime_package dep_package_info then 
+            get_runtime_module_path dep_module_id current_package_info module_system
+          else 
             begin match module_system with 
               | NodeJS | Es6 -> 
                 dep_pkg.pkg_rel_path // js_file
diff --git a/lib/4.06.1/whole_compiler.ml b/lib/4.06.1/whole_compiler.ml
index 48d268230a..8efb087b8b 100644
--- a/lib/4.06.1/whole_compiler.ml
+++ b/lib/4.06.1/whole_compiler.ml
@@ -294325,7 +294325,7 @@ val no_export: bool ref
 val as_ppx : bool ref 
 
 val mono_empty_array : bool ref
-
+val customize_runtime : string option ref 
 end = struct
 #1 "js_config.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
@@ -294420,7 +294420,7 @@ let as_ppx = ref false
 
 let mono_empty_array = ref true
 
-
+let customize_runtime = ref None 
 end
 module Ast_config : sig 
 #1 "ast_config.mli"
@@ -370595,7 +370595,19 @@ let runtime_test_package_specs : t = {
   name = Pkg_runtime; 
   module_systems = []
 }
-let same_package_by_name (x : t) (y : t) = x.name = y.name 
+
+let same_package_by_name (x : t) (y : t) =
+  match x.name with 
+  | Pkg_empty -> 
+    y.name = Pkg_empty
+  | Pkg_runtime -> 
+    y.name = Pkg_runtime 
+  | Pkg_normal s -> 
+    begin match y.name with 
+    | Pkg_normal y -> s = y
+    | Pkg_empty | Pkg_runtime -> false
+    end
+   
 
 let is_runtime_package (x : t) = 
     x.name = Pkg_runtime
@@ -381238,7 +381250,12 @@ let get_runtime_module_path
           (*Invariant: the package path to bs-platform, it is used to 
             calculate relative js path
           *)
-          ((Filename.dirname (Filename.dirname Sys.executable_name)) // dep_path // js_file)  
+          (match !Js_config.customize_runtime with 
+           | None ->
+             ((Filename.dirname (Filename.dirname Sys.executable_name)) // dep_path // js_file)
+           | Some path -> 
+             path //dep_path // js_file 
+          )  
 
 
 
@@ -381300,6 +381317,9 @@ let string_of_module_id
                   which is guaranteed by [-bs-package-output]
               *)
           else  
+          if Js_packages_info.is_runtime_package dep_package_info then 
+            get_runtime_module_path dep_module_id current_package_info module_system
+          else 
             begin match module_system with 
               | NodeJS | Es6 -> 
                 dep_pkg.pkg_rel_path // js_file
@@ -435915,7 +435935,18 @@ let setup_error_printer (syntax_kind : [ `ml | `reason | `rescript ])=
 
 
   
-  
+let setup_runtime_path path = 
+  let u0 = Filename.dirname path in 
+  let std = Filename.basename path in 
+  let _path = Filename.dirname u0 in 
+  let rescript = Filename.basename u0 in 
+  (match rescript.[0] with 
+   | '@' -> 
+     Bs_version.package_name := rescript ^ "/" ^ std;
+   | _ -> Bs_version.package_name := std
+   | exception _ -> 
+     Bs_version.package_name := std);
+  Js_config.customize_runtime := Some path
 
 let handle_reason (type a) (kind : a Ml_binary.kind) sourcefile ppf  = 
   setup_error_printer `reason;
@@ -436324,6 +436355,8 @@ let buckle_script_flags : (string * Bsc_args.spec * string) array =
     "<list>  Enable or disable error status for warnings according\n\
          to <list>.  See option -w for the syntax of <list>.\n\
          Default setting is " ^ Bsc_warnings.defaults_warn_error;    
+    "-runtime",string_call setup_runtime_path,     
+    "*internal* Set the runtime directory";
     "-make-runtime", unit_call Js_packages_state.make_runtime,
     "*internal* make runtime library";  
     "-make-runtime-test", unit_call Js_packages_state.make_runtime_test,