How to easier to rewrite code to work with binary data?

[mryau]

Hello,
I want to work with structured messages packed to protocol buffers.
Is it right way to parametrize Router module by message type or you do not interested in such patches?

[hcarty]

Do you have an example of what you would want the interface to look like? I could see something along the lines of the following being simple but useful wrappers:

val make_send : ('a -> string list) -> _ Lwt_zmq.Socket.t -> ('a -> unit Lwt.t)
val make_recv : (string list -> 'a) -> _ Lwt_zmq.Socket.t -> (unit -> 'a Lwt.t)

val make_send_s : ('a -> string list Lwt.t) -> _ Lwt_zmq.Socket.t -> ('a -> unit Lwt.t)
val make_recv_s : (string list -> 'a Lwt.t) -> _ Lwt_zmq.Socket.t -> (unit -> 'a Lwt.t)

make_send to_message socket would return a function which sends values over socket, serialized by to_message.

make_recv of_message socket would return a function which received values over socket, deserialized by of_message.

The _s versions would take a cooperative function for the (de)serialization process.

[mryau]

Hello,

currently I need only properly typed messages on zmq bus so I prefer following modification of your code with functor:

module type IDType = sig
  type t
  val to_string : t -> string
  val of_string : string -> t
end

module FLSocket(DType : IDType) = struct

  type 'a t = {
    socket : 'a ZMQ.Socket.t;
    fd : Lwt_unix.file_descr;
  }

...
  let recv s =
    wrap (fun s -> let r = ZMQ.Socket.recv ~block:false s in DType.of_string r) s

  let send ?more s m =
    wrap (fun s -> ZMQ.Socket.send ?more ~block:false s (DType.to_string m)) s
...
end

type vlan = int list [@@deriving protobuf { protoc }]
type io =
        | Port of int [@key 1]
        | Agg of int [@key 2]
        | Vlan of vlan [@key 3]
        [@@deriving protobuf { protoc }]

type router = io list [@@deriving protobuf { protoc }]

module LSocket =
  FLSocket(struct
    type t = router
    let to_string = Protobuf.Encoder.encode_exn router_to_protobuf
    let of_string = Protobuf.Decoder.decode_exn router_from_protobuf
  end)

I don't know should I send such modification as pull request to your repository?