Lisp, iterating backwards

Question

Is there a way (with loop or iterate, doesn't matter) to iterate over sequence backwards?

Apart from (loop for i downfrom 10 to 1 by 1 do (print i)) which works with indexes, and requires length, or (loop for elt in (reverse seq)) which requires reversing sequence (even worse then the first option).

Answer 1

Iterate can do it:

(iterate (for x :in-sequence #(1 2 3) :downto 0)
         (princ x))
; => 321

As others have noted, this will be very inefficient if used on lists.