;; ,open threads rendezvous rendezvous-channels

(define (display-message-rv rv ack-message nack-message)
  (with-nack (lambda (nack)
	       (spawn 
		(lambda ()
		  (sync nack)
		  (display nack-message)
		  (newline)))
	       (wrap rv (lambda (ignore)
			  (display ack-message)
			  (newline))))))

(define (numbers n)
  (let lp ((n n) (lst '()))
    (if (zero? n)
	lst
	(lp (- n 1) (cons n lst)))))

(define (make-channel-list n)
  (map (lambda (n)
	 (cons n (make-channel)))
       (numbers n)))

(define (ack-message n)
  (string-append "ack " (number->string n)))

(define (nack-message n)
  (string-append "nack " (number->string n)))

(define (wait-for-data channels)
  (spawn 
   (lambda ()
     (let lp ()
       (apply select 
	      (map (lambda (n.ch)
		     (display-message-rv 
		      (receive-rv (cdr n.ch))
		      (ack-message (car n.ch))
		      (nack-message (car n.ch))))
		   channels))
       (lp)))))