(define (cycle? list)
  (define parsed-pairs '())

  (define (add-pair! pair)
    (set! parsed-pairs (cons pair parsed-pairs)))

  (define (has? list)
    (cond
      [(null? list) #f]
      [(member list parsed-pairs) #t]
      [else
       (begin
         (add-pair! list)
         (has? (cdr list)))]))

  (has? list))