[racket] overlay and overlay/xy

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Mon Jan 31 10:08:26 EST 2011

Yes, it is. Unfortunately I did not make this clear to at least 1
textbook author whose text now depends directly on 2htdp/image. I hope
to make this clear in the future to avoid these kinds of problems.


On Monday, January 31, 2011, Shriram Krishnamurthi <sk at cs.brown.edu> wrote:
> I thought our working principle was that textbook authors should
> create their own Teachpacks/language levels, not rely on those for
> HtDP being stable for their purposes.
> This would certainly be a good time to make that point clear.
> Shriram
> On Mon, Jan 31, 2011 at 6:58 AM, Robby Findler
> <robby at eecs.northwestern.edu> wrote:
>> In addition to these onlist replies, I have now heard one off-list
>> reply that is fairly strongly against changing it, pointing out that
>> people write books that depend on these details.
>> Possibly adding a new function is the most viable route?
>> Robby
>> On Sun, Jan 30, 2011 at 10:00 PM, Marc L. Smith <mlsmith at cs.vassar.edu> wrote:
>>> I taught from HtDP/2e last semester, using 2htdp/image, and had similar
>>> experiences with my students playing with overlay/xy. I must admit it wasn't
>>> what I expected after using overlay, and I agree with Don. With the caveat
>>> that I'm not concerned about backward compatibility, I would prefer to see
>>> overlay/xy updated to be consistent with overlay, in the way Don described.
>>> Short of this possibility, a revision to the documentation would also be
>>> helpful...  :-)
>>> Thanks to Don for articulating this behavior so well, and to Robby for
>>> soliciting further opinions!
>>> Marc
>>> On Sun, Jan 30, 2011 at 10:33 PM, <users-request at racket-lang.org> wrote:
>>> Message: 4
>>> Date: Sun, 30 Jan 2011 21:04:52 -0600
>>> From: Robby Findler <robby at eecs.northwestern.edu>
>>> To: Don Blaheta <dblaheta at monm.edu>
>>> Cc: "users at racket-lang.org" <users at racket-lang.org>
>>> Subject: Re: [racket] overlay and overlay/xy
>>> Message-ID:
>>>        <AANLkTinGAs=xM7GQyjj+q5BLmHMCjMiC_8TNxHn31xJD at mail.gmail.com>
>>> Content-Type: text/plain; charset=UTF-8
>>> I find this to be a compelling argument but I am worried about
>>> backwards compatibilty for others.
>>> The least I can do is a better job documenting this (and thanks to
>>> your message I think I'll be able to do that) but I'm not sure about
>>> changing the semantics.
>>> Do others that may depend on 2htdp/image have an opinion?
>>> Robby
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