CS代考程序代写 ;(define (delay exp)

;(define (delay exp)
; (lambda () exp)) ;error b/c applicative order
;(define (force delayed-exp)
; (delayed-exp))

(define-syntax delay
(syntax-rules ()
((delay exp) (lambda() exp))))
(define-syntax force
(syntax-rules ()
((force exp)(exp))))

(define (foo x y)
(if (= x 0) x (force y)))
(foo (* 3 0) (delay (/ 3 0)))