1 665c255d 2023-08-04 jrmu (define (cycle? x)
 2 665c255d 2023-08-04 jrmu   (define (compare end-index current-index z current-list)
 3 665c255d 2023-08-04 jrmu     (cond ((eq? end-index current-index) false)
 4 665c255d 2023-08-04 jrmu 	  ((eq? current-list z) true)
 5 665c255d 2023-08-04 jrmu 	  (else (compare end-index
 6 665c255d 2023-08-04 jrmu 			 (+ 1 current-index)
 7 665c255d 2023-08-04 jrmu 			 z
 8 665c255d 2023-08-04 jrmu 			 (cdr current-list)))))
 9 665c255d 2023-08-04 jrmu   (define (find-cycle z i)
10 665c255d 2023-08-04 jrmu     (cond ((null? z) false)
11 665c255d 2023-08-04 jrmu 	  ((compare i 0 z x) true)
12 665c255d 2023-08-04 jrmu 	  (else (find-cycle (cdr z) (+ 1 i)))))
13 665c255d 2023-08-04 jrmu   (if (not (pair? x))
14 665c255d 2023-08-04 jrmu       (error "Argument of cycle? must be a pair")
15 665c255d 2023-08-04 jrmu       (find cycle (cdr x) 1)))