Lisp---数列反转

> (define a (list 1 2 3 4))
> a
(1 2 3 4)
> (define (reverse items)
(define (cons-rev items ans)
(if (equal? items '( ))
ans
(cons-rev (cdr items) (append (list (car items)) ans))))
(cons-rev items '( )))
> (reverse a)
(4 3 2 1)
>