(define make-conses
  (lambda (xs)
    (if (eq xs nil)
        nil
        `(cons ,(car xs) ,(make-conses (cdr xs))))))

(define make-selectors
  (lambda (xs s)
    (if (eq nil xs)
        nil
        `(if (eq msg ',(car xs))
             (lambda (s) (car ,s))
             ,(make-selectors (cdr xs) `(cdr ,s))))))

(defmacro define-struct (name fields)
  `(let ((obj
          (lambda (msg)
            (if (eq msg 'new)
                (lambda ,fields
                  (cons ',name ,(make-conses fields)))
                ,(make-selectors fields '(cdr s))))))
     (defmacro ,name (msg)
       `(',obj ',msg))))