Re: [Caml-list] js_of_ocaml with node

["Mauricio Fernández" <mfp@acm.org>]

On Wed, Apr 29, 2015 at 05:03:21PM -0500, Helmut Brandl wrote:
> Thanks to all for the hints.
> 
> I think I have to dig into the documentation of js_of_ocaml to
> resolve the problem.

I've got some bindings for nodejs stuff including FS operations, sockets,
events, processes, etc.; will try to publish it tomorrow. Note that some
nodejs functions require variadic callbacks as supported by the patches
available at https://github.com/ocsigen/js_of_ocaml/issues/273

The hand-written bindings look like this (just a sneak peek):

node_require.eliom:

    {client{
    let require x =
      let require = Js.Unsafe.eval_string "require" in
        require##call(require, Js.string x)
    }}

    (* vim: set ft=ocaml: *)


node_fs.eliom:


    {client{
    open Printf
    open Lwt

    class type error =
    object
      method message : Js.js_string Js.t Js.prop
    end

    type maybe_error = error Js.t Js.opt

    class type stats =
    object
      method dev     : int Js.readonly_prop
      method ino     : int Js.readonly_prop
      method mode    : int Js.readonly_prop
      method nlink   : int Js.readonly_prop
      method uid     : int Js.readonly_prop
      method gid     : int Js.readonly_prop
      method rdev    : int Js.readonly_prop
      method size    : float Js.t Js.readonly_prop
      method blksize : int Js.readonly_prop
      method blocks  : int Js.readonly_prop
      method atime   : Js.date Js.t Js.readonly_prop
      method mtime   : Js.date Js.t Js.readonly_prop
      method ctime   : Js.date Js.t Js.readonly_prop
    end

    and watch_options =
    object
      method persistent : bool Js.t Js.prop
    end

    class type fs =
    object
      method existsSync : Js.js_string Js.t -> bool Js.t Js.meth
      method exists : Js.js_string Js.t -> (bool Js.t -> unit) Js.callback -> unit Js.meth

      method readFile :
        Js.js_string Js.t ->
        (maybe_error -> Node_net.buffer Js.t -> unit) Js.callback -> unit Js.meth

      method readFileSync : Js.js_string Js.t -> Node_net.buffer Js.t Js.meth

      method readdirSync : Js.js_string Js.t -> Js.js_string Js.t Js.js_array Js.t Js.meth

      method statSync : Js.js_string Js.t -> stats Js.t Js.opt Js.meth
      method lstatSync : Js.js_string Js.t -> stats Js.t Js.opt Js.meth

      method mkdir :
        Js.js_string Js.t -> int -> (maybe_error -> unit) Js.callback -> unit Js.meth
      method mkdirSync : Js.js_string Js.t -> int -> unit Js.meth

      method unlink : Js.js_string Js.t -> (maybe_error -> unit) Js.callback -> unit Js.meth
      method unlinkSync : Js.js_string Js.t -> unit Js.meth

      method watch : 'a. Js.js_string Js.t -> (#watch_options as 'a) Js.t ->
                     (Js.js_string -> Js.js_string -> unit) Js.callback -> unit Js.meth
    end

    let fs : fs Js.t = Node_require.require "fs"


    let err_callback1 u err =
      match Js.Opt.to_option err with
          None -> Lwt.wakeup_later u ()
        | Some err -> Lwt.wakeup_later_exn u (Failure (Js.to_string err##message))

    let bool_callback1 u b = Lwt.wakeup_later u (Js.to_bool b)

    let wrap_async1 callback f =
      let t, u = Lwt.wait () in
        f (Js.wrap_callback (callback u));
        t

    let exists s = wrap_async1 bool_callback1 (fun cb -> fs##exists(Js.string s, cb))
    let unlink s = wrap_async1 err_callback1 (fun cb -> fs##unlink(Js.string s, cb))

    let read_file fname =
      let t, u = Lwt.wait () in

      let on_read err data =
        if Js.Opt.test err then
          Lwt.wakeup_later_exn u (Failure (sprintf "could not read %S" fname))
        else Lwt.wakeup_later u (Js.to_string data##toString())
      in
        fs##readFile(Js.string fname, Js.wrap_callback on_read);
        t
    }}
    (* vim: set ft=ocaml: *)

-- 
Mauricio Fernández