(define reverse
  (lambda (lst)
    (reverse-onto lst '())))

(define reverse-onto
  (lambda (lst tail)
    (if (null? lst)
        tail
        (reverse-onto (cdr lst)
                      (cons (car lst)
                            tail)))))

(define reverse!
  (lambda (lst)
    (reverse-onto! lst '())))

(define reverse-onto!
  (lambda (lst tail)
    (if (null? lst)
        tail
        (let ((the-first-pair lst)
              (the-rest-of-lst (cdr lst)))
          (set-cdr! the-first-pair tail)
          (reverse-onto! the-rest-of-lst
                         the-first-pair)))))