;; Speicherzellen in CML mit selektiver Kommunikation

(define-record-type :cell
  (really-make-cell ref-channel set!-channel)
  cell?
  (ref-channel cell-ref-channel)
  (set!-channel cell-set!-channel))

(define (make-cell value)
  (let ((ref-channel (make-channel))
	(set!-channel (make-channel)))
    (spawn
     (lambda ()
       (let loop ((value value))
	 (select
	  (list
	   (wrap (send-rv ref-channel value)
		 (lambda (ignore)
		   (loop value)))
	   (wrap (receive-rv set!-channel)
		 loop))))))
    (really-make-cell ref-channel set!-channel)))

(define (cell-ref cell)
  (receive (cell-ref-channel cell)))

(define (cell-set! cell value)
  (send (cell-set!-channel cell) value))