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

From: Jos Koot (jos.koot at telefonica.net)
Date: Wed Nov 26 14:39:39 EST 2008

----- 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.


> 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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