2.40.scm

(load "./2.39")
(use math.prime)

(define (enumerate-interval low high)
  (if (> low high)
    nil
    (cons low (enumerate-interval (+ low 1) high))))

(define (flatmap proc seq)
  (accumulate append nil (map proc seq)))

(define (unique-pairs n)
  (flatmap (lambda (i)
             (map (lambda (j) (list i j))
                  (enumerate-interval 1 (- i 1))))
           (enumerate-interval 2 n)))

(define prime? miller-rabin-prime?)

(define (prime-sum? pair)
  (prime? (+ (car pair) (cadr pair))))

(define (make-pair-sum pair)
  (list (car pair) (cadr pair) (+ (car pair) (cadr pair))))

(define (prime-sum-pairs n)
  (map make-pair-sum
       (filter prime-sum?
               (unique-pairs n))))

(define (main args)
  (print (unique-pairs 5))
  (print (prime-sum-pairs 6))
  )