(define-syntax defclass (name members :rest body)
  "Macro for creatating classes."
  (defun underscore (sym)
    (string->symbol (concat-strings "_" (symbol->string sym))))

  (define underscored-members (map underscore members))

  ;; the wrapping let environment
  (define let-body (list 'let (zip members underscored-members)))

  ;; the body
  (map (lambda (fun) (append let-body fun)) body)

  ;; the dispatch function
  (append let-body (list 'special-lambda '(message :rest args)
                         "This is the docs for the handle"
                         '(eval (extend (list message) args))))


  ;; stuff it all in the constructor function
  (eval (list 'defun (string->symbol (concat-strings "make-" (symbol->string name))) underscored-members
              "This is the handle to an object of the class "
              let-body)))

;; (v1 print)
;; (v1 length)
;; (v1 get-x)
;; (v1 set-x 10)

(defclass vector3 (x y z)
  (defun get-x () x)
  (defun get-y () y)
  (defun get-z () z)

  (defun set-x  (new-x) (mutate x new-x))
  (defun set-y  (new-y) (mutate y new-y))
  (defun set-z  (new-z) (mutate z new-z))

  (defun length ()
    (** (+ (* x x) (* y y) (* z z)) 0.5))

  (defun scale (fac)
    (mutate x (* fac x))
    (mutate y (* fac y))
    (mutate z (* fac z))
    fac)

  (defun add (other)
    (make-vector3
     (+ x (other get-x))
     (+ y (other get-y))
     (+ z (other get-z))))

  (defun subtract (other)
    (make-vector3
     (- x (other get-x))
     (- y (other get-y))
     (- z (other get-z))))

  (defun scalar-product (other)
    (+ (* x (other get-x))
       (* y (other get-y))
       (* z (other get-z))))

  (defun cross-product (other)
    (make-vector3
     (- (* y (other get-z)) (* z (other get-y)))
     (- (* z (other get-x)) (* x (other get-z)))
     (- (* x (other get-y)) (* y (other get-x)))))

  (defun printout ()
    (printf "[vector3] (" x  y  z ")"))
  )

(define v1 (make-vector3 1 2 3))
(define v2 (make-vector3 3 2 1))