another error in my tiny test program

[Steve Strassmann <straz@cambridge.apple.com>]

Date: Mon, 27 Jul 1992 11:36:29 -0500
To: Steve Strassmann <straz@cambridge.apple.com>
From: bill@cambridge.apple.com (Bill St. Clair)
Subject: Re: Error in my tiny test program

>(defun drop-ball (&optional (window *window*))
>  (let ((v 1)               ; vertical position
>        (h 1)               ; horizontal position
>        (size 10)           ; size of ball
>        (height 20))        ; initial height of ball
>    (while (< height 120)
>      (if (oddp h) 
>        (visible window)
>        (invisible window))
>      (paint-oval window h v (+ h size) (+ v size))
>      (setf v (+ v 3) 
>            h (+ h 5)
>            height (+ height v)))))

I have to thank Bill for pointing out some bugs in my
last message.

The WHILE macro is not part of CLtL2. It is available
in MCL 2.0 in the CCL package, but it is not exported.
So, if you want to use it, you have to say CCL::WHILE.

Also, PAINT-OVAL is part of the QUICKDRAW example file. 
You either need to (require "QUICKDRAW") or use the
#_paintoval trap directly.