(defun sym (&rest things)
  (intern
   (string-upcase
    (with-output-to-string (s)
      (dolist (th things)
        (princ th s))))))

(defmacro lazy (args &body body)
  `(make-instance 'lazy-function
                  :fun (lambda ,args ,@body)))

(defmacro write-lazy (name)
  (let ((class-name (sym name "-function")))
    `(defmacro ,name (args &body body)
       `(make-instance ',',class-name
                       :fun (lambda ,args ,@body)))))

(write-lazy lazy)