(defun integer-power (n k) ;A highly "bummed" integer
(declare (integer n)) ; exponentiation routine
(declare (type (integer 0 *) k))
(labels ((expt0 (x k a)
(declare (integer x a) (type (integer 0 *) k))
(cond ((zerop k) a)
((evenp k) (expt1 (* x x) (floor k 2) a))
(t (expt0 (* x x) (floor k 2) (* x a)))))
(expt1 (x k a)
(declare (integer x a) (type (integer 1 *) k))
(cond ((evenp k) (expt1 (* x x) (floor k 2) a))
(t (expt0 (* x x) (floor k 2) (* x a))))))
(expt0 n k 1)))

不错啊~~~
真酷