#lang racket

(require "os-big-bang.rkt")
(require "os-udp.rkt")

(define counter
  (os-big-bang 0
    (send-message `(request create-echo-socket (udp new 5678 65536)))
    (subscribe/fresh sub
      (message-handlers current-counter
	[`(reply create-echo-socket ,sname)
	 (transition current-counter
	   (unsubscribe sub)
	   (subscribe 'packet-handler
	     (message-handlers current-counter
	       [(udp-packet source (== sname) #"get")
		(transition (+ current-counter 1)
		  (send-message
		   (udp-packet sname source
			       (integer->integer-bytes current-counter 8 #f))))])))]))))

(ground-vm
 (os-big-bang 'none
   (spawn udp-driver)
   (spawn counter)))