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Constructive Linked List: Reverse

reverse makes a new linked list whose elements are in the reverse order of the original list; the original is unchanged.

(reverse '(a b c))      ->  (c b a)
This function takes advantage of the fact that cons creates a list in the reverse order of the conses.

public static Cons reverse (Cons lst) {
  Cons answer = null;
  for ( ; lst != null; lst = rest(lst) )
    answer = cons( first(lst), answer );
  return answer; }

(defun reverse (lst)
  (let (answer)
    (setq answer '())
    (while (consp lst)
      (setq answer (cons (first lst) answer))
      (setq lst (rest lst)) )
    answer ))