product-prime-1-1000.scm

(define (product a next b)
  (define (iproduct p a next)
    (if (<= a b)
      (iproduct (* a p) (next a) next)
      p))
  (iproduct 1 a next))

(define (isprime? x)
  (define (iisprime? i)
    (cond ((> i (sqrt x)) #t)
          ((= (modulo x i) 0) #f)
          (else (iisprime? (+ i 1)))))
  (iisprime? 2))

(define (next-prime x)
  (define (f i)
    (if (isprime? i)
      i
      (f (+ i 1))))
  (f (+ x 1)))

(print (product 2 next-prime 1000))