;; Should test for "is in hash table", rather than NIL-ness
(defmacro defmemo (name lambda-list &rest body)
(let ((memo (make-hash-table :test #'equal)) (tmp (gensym)))
`(flet ((,tmp ,lambda-list ,@body))
(defun ,name (&rest args)
(or (gethash args, memo)
(setf (gethash args ,memo) (apply #',tmp args)))))))
