[racket] overlay and overlay/xy

From: Shriram Krishnamurthi (sk at cs.brown.edu)
Date: Mon Jan 31 09:39:31 EST 2011

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.


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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