From Newsgroup: comp.lang.lisp

Pascal J. Bourguignon wrote:

(defun factorial (n)
(loop with result = 1
for i from 1 to n do
(setf result (* result i))
finally (return result)))

If you use loop, it's better to start multiplying the biggest integers
first, in case it goes into bignums:

cl-user> (defun factorial> (n)
(loop with result = 1
for i from 1 to n do
(setf result (* result i))
finally (return result)))

factorial>
cl-user> (defun factorial< (n)
(loop with result = 1
for i from n downto 1 do
(setf result (* result i))
finally (return result)))

(define (factorial n)
(do ((i n (- i 1))
(result 1 (* result i)))
((< i 1) result)))
--
The good news is, it's not Lisp that sucks, but Common Lisp. --- Paul Graham --- Synchronet 3.21a-Linux NewsLink 1.2