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.
(defun reverse (lst)
(let (answer)
(setq answer '())
(while (consp lst)
(setq answer (cons (first lst) answer))
(setq lst (rest lst)) )
answer ))
public static Cons reverse (Cons lst) {
Cons answer = null;
while ( consp(lst) ) {
answer = cons( first(lst), answer );
lst = rest(lst); }
return answer; }