gistfile1.scm

(frdef gcd ()
       ; gcd's identity:
       () 0
       ((int? a))  (abs a)

       ; Make sure that they're sorted ascending
       (((curry both int? (curry ! <=)) *l)) (apply gcd (sort l))

       ; Trivial case:
       (a 0) (abs a) ; As making it here means a is negative.
       (0 a) a
       ; If there are more than two args, reduce:
       (a b (true *rest (1 -1))) (apply gcd (cons (gcd a b) rest))

       ; Handle negatives
       (((curry both int? (curry > 0)) a) b) (gcd (abs a) b)

       ; Oh, the actual math should probably happen somewhere.  Here's good.
       (a b) (gcd (% b a) a))

(frdef lcm ()
       () 1
       a (abs a)
       (a b) (/ (* a b) (gcd a b))
       (a b *rest) (apply lcm (cons (lcm a b) rest)))