defmemo/int->int

defmemo.lisp

; depends on alexandria
; memoizes int->int functions in a mutable vec
(defmacro defmemo/int->int (size name (in) &body body)
  (let ((memo-name (read-from-string (format nil "~a-memo" name))))
    `(progn (defvar ,memo-name (make-array (+ 1 ,size) :initial-element nil))
            (defun ,name (,in)
              (if-let ((memo (aref ,memo-name ,in)))
                memo
                (setf (aref ,memo-name ,in) (progn ,@body)))))))