Fw: [plt-scheme] Mutable and immutable pairs in PLT Scheme

I should add that I have severeal PLT implementations of SRFI-41. My latest 
one does not use mutable pairs, but it deviates from the standard 
implementation by streams not being a distinct data type. I have asked 
private advice from someone I trust, on whether not this would be an a good 
idea.. I await his answer before deciding whether or not presenting it to 
this list. I also have an implementation that fully conforms to the standard 
SRFI 41 document, but it requires a generalizarion of PLT's implementation 
of SRFI 45 (which would include `define-promise-type' and  which I have 
prepared too, of course, and shall distribute if the PLT community is 
interested) I am not reluctant too distribute my code, but on the other hand 
I don't wish to spoil this mailing list with yet another idea of how to 
implement SRFI 45 or SRFI 41. Particularly SRFI 45 is a delicate piece of 
code, which should not be replaced by code that cannot fully be trusted. Oh 
yes, I trust my code, but would you?
Jos

----- Original Message ----- 
From: "Jos Koot" <jos.koot at telefonica.net>
To: "Tom Gordon" <thomas.gordon at fokus.fraunhofer.de>; "Matthew Flatt" 
<mflatt at cs.utah.edu>
Cc: "Abdulaziz Ghuloum" <aghuloum at cs.indiana.edu>; "PLT List" 
<plt-scheme at list.cs.brown.edu>
Sent: Wednesday, November 26, 2008 8:39 PM
Subject: Re: [plt-scheme] Mutable and immutable pairs in PLT Scheme


>
> ----- Original Message ----- 
> From: "Tom Gordon" <thomas.gordon at fokus.fraunhofer.de>
> To: "Matthew Flatt" <mflatt at cs.utah.edu>
> Cc: "Abdulaziz Ghuloum" <aghuloum at cs.indiana.edu>; "PLT List" 
> <plt-scheme at list.cs.brown.edu>
> Sent: Wednesday, November 26, 2008 4:14 PM
> Subject: Re: [plt-scheme] Mutable and immutable pairs in PLT Scheme
>
>
>>
>> On Nov 26, 2008, at 3:49 PM, Matthew Flatt wrote:
>>
>>>> While I can't claim any Scheme implementation (#3) or programming
>>>> language design experience (#2) when it comes to this topic, it does
>>>> seem pretty clear to me that taking this step would create a  marketing
>>>> nightmare for PLT.
>>>
>>> Well, the Scheme community being what it is, most any significant
>>> action creates PR and diplomacy problems. We can deal with them,
>>> though, if the action is otherwise useful enough.
>>>
>>> So, to help gauge usefulness for this potential action, I'll revise  the
>>> question:
>>>
>>> Does anyone actually use (and expect to continue to use) the `(rnrs
>>> mutable-pairs)' library in PLT Scheme's R6RS?
>>
>>
>> Our Carneades system <http://carneades.berlios.de> uses the following 
>> libraries which import and use the (rnrs mutable-pairs) library:
>>
>> 1. Alex Shinns' portable hygenic pattern matcher
>> 2. Dorai Sitaram's portable regular expressions library
>> 3. Busch, Holm, and Dickey's Portable Scheme Interface to the Tk GUI 
>> toolkit
>> 4. Olin Shiver's SRFI-1 List Processing Library
>> 5. Ray Dillinger's implementations of "write-with-shared-structure"  and 
>> "read-with-structure" for Larceny and Ypsilon, which is part of  his port 
>> of various SRFI's to R6RS.
>> 6. Philip Bewig's R6RS implementation of the SRFI-41 stream library.
>
> True, but it could as easily use immutable pairs of boxes.
> Conversion would not take more than an hour, I guess.
> I am willing and well prepared to do that.
>
> Jos
>
>>
>> Nonetheless, we are in favor of this idea.  We would much prefer  greater 
>> interoperability with the rest of PLT Scheme to retaining  support for 
>> the (rnrs mutable-pairs) library, even though this would  sacrifice some 
>> conformance with the standard.
>>
>> We are willing try to modify the libraries we use, listed above, to 
>> remove their dependencies on mutable pairs, in collaboration with  their 
>> authors.
>>
>> -Tom
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