RosettaCodeData/Task/Function-definition/Common-Lisp/function-definition-2.lisp

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Common Lisp
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2013-04-10 21:29:02 -07:00
(define-compiler-macro multiply (&whole expr a b)
(if (and (constantp a) (constantp b))
(* (eval a) (eval b))
expr)) ;; no macro recursion if we just return expr; the job is done!