Copying a List

(define (copy-list-1 l)
  (cond ((null? l) '())
	((pair? l)
	 (cons (copy-list-1 (car l))
	       (copy-list-1 (cdr l))))
	(else l)))

(define x '(a b c))
(define y (cons x x))
y                      ; ((a b c) a b c)
(eq? (car y) (cdr y))  ; #T
(define z (copy-list-1 y))
z                      ; ((a b c) a b c)
(eq? (car z) (cdr z))  ; #F

Jim Miller