;; csp. processes are represented as delayed functions

(define (STOP) (delay 'bleep))

(define (prefix c P)
  (lambda (x)
    (if (eq? x c) 
	P
	'bleep)))

(define (choise2 c P d Q)
  (lambda (x)
    (if (eq? x c)
	P
	(if (eq? x d) 
	    Q
	    'bleep))))

(define (menu A P)
  (if (null? A)
      '()
      (if (eq? ((force P) (car A)) 'bleep)
	  (menu (cdr A) P)
	  (cons (car A) (menu (cdr A) P)))))

;; lazy eval?
(define VMS
  (delay 
    (prefix 'coin 
	    (prefix 'choc VMS))))