Dependent typing in common lisp

dependent-typed.lisp

;;--------------------------------------------------------------------
;;-- Types

;; slot-number type 
(defun within-slot-number-rangep (n)
  (not (or (< n 0) (> n 255))))

(deftype slot-number ()
  `(and fixnum (satisfies within-slot-number-rangep)))

;; vitality type
(defun within-vitality-rangep (v)
  (not (or (< v -1) (> v 65535))))

(deftype vitality ()
  `(and fixnum (satisfies within-vitality-rangep)))

;; field type
(deftype field ()
  `(or fixnum function))

(deftype field-application ()
  `(and function))

;;--------------------------------------------------------------------
;;-- Structures

;; slot structure
(defstruct slot
  (number   0          :type index)
  (field    #'identity :type field)
  (vitality 10000      :type vitality))