(* An example with session types, including choice. (Type error) *)

#load "libthread"
#load "libsessiontype"

open SessionType

type 'a protocol = !'a; !'a; ?'a; 1
                   |+|
                   !'a; ?'a; 1

let server =
  fun c : int protocol dual channel ->
    match follow c with
    | Left c ->
        let (x, _) = recv c in
        let (y, c) = recv c in
          send c (x + y);
          ()
    | Right c ->
        let (x, c) = recv c in
          send c (0 - x);
          ()

let client =
  fun c : int protocol channel ->
    fun (x : int) (y : int) ->
      let c = sel1 c in
      let c = send c x in
      let c = send c y in
      let (r, _) = recv c in
        r

let main =
  fun (x : int) (y : int) ->
    let rv = newRendezvous[int protocol] () in
      AThread.fork (fun () -> server (accept rv));
      client (request rv) x y

in print (main 3 4)