Destructive functions in Lisp often begin with n. nreverse reverses a list in place by turning the pointers around.
(nreverse (list 'a 'b 'c)) -> (c b a)
(defun nreverse (lst)
(let (last next)
(setq last nil)
(while (not (null lst))
(setq next (rest lst))
(setf (rest lst) last)
(setq last lst)
(setq lst next) )
last))
public static Cons nreverse (Cons lst) {
Cons last = null; Cons next;
while (lst != null)
{ next = rest(lst);
setrest(lst, last);
last = lst;
lst = next; };
return last; }