Add [@@@js.require]

VALUES.md

@@ -363,6 +363,22 @@ For instance, the following annotated modules will generate the same code:
   end [@js.scope "inner"] [@js.scope "outer"]
 ```
 
+Require
+-------
+
+The signature attribute `[@@@js.require "name"]` is equivalent to making the
+current global object the result of `require("name")`. This is useful to bind
+Node libraries. For instance,
+
+```ocaml
+module[@js.require "crypto"] C: sig
+  type hash
+  val create_hash: unit -> hash [@@js.global]
+end
+```
+
+will bind the `createHash` function of the Node library `crypto`.
+
 First-class modules
 -------------------
 

examples/test/test_bindings.mli

@@ -356,3 +356,14 @@ end
 module Dict : sig
   type t = { h : ((string * int) list [@js.dict]) }
 end
+
+module X : sig
+  [@@@js.require "foo"]
+
+  val x : int -> int [@@js.global]
+  val y : string [@@js.global]
+end
+
+module[@js.require "crypto"] Crypto : sig
+  val z : int [@@js.global]
+end

ppx-lib/gen_js_api_ppx.ml

@@ -895,6 +895,9 @@ let ojs_set o s v =
   else
     ojs "set_prop" [o; ojs "string_to_js" [str s]; v]
 
+let node_require e =
+  ojs "apply" [ojs "variable" [str "require"]; Exp.array [ojs "string_to_js" [e]]]
+
 let select_path o s =
   let rec select_path o = function
     | [] -> assert false
@@ -1605,13 +1608,16 @@ let process_fields ctx ~global_attrs l =
   jsname, (* JS name *)
   parse_typ ctx ~global_attrs typ
 
-
 let global_object ~global_attrs =
   let rec traverse = function
     | [] -> ojs_global
     | hd :: tl ->
         begin match get_expr_attribute "js.scope" [hd] with
-        | None -> traverse tl
+        | None ->
+            begin match get_expr_attribute "js.require" [hd] with
+            | None -> traverse tl
+            | Some exp -> node_require exp
+            end
         | Some {pexp_desc=Pexp_constant (Pconst_string (prop, _, _)); _} -> ojs_get (traverse tl) prop
         | Some {pexp_desc=Pexp_tuple path; _} ->
           let init = traverse tl in