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

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Wed Nov 26 09:49:04 EST 2008

At Wed, 26 Nov 2008 08:35:57 -0600, "Grant Rettke" wrote:
> On Wed, Nov 26, 2008 at 7:57 AM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> > At Tue, 25 Nov 2008 23:28:16 -0500, Abdulaziz Ghuloum wrote:
> >> This is what I'd thought would happen; ditch the (rnrs mutable-pairs)
> >> library for the sake of (1) more interoperability with the PLT modules,
> >> (2) more encouragement for people, even outside of PLT, to get rid of
> >> set-car! and set-cdr! in their code (which should be easy according to
> >> Matthews's blog), and (3) going through less hassle implementing what
> >> is effectively a parallel universe just for mutable pairs.
> >>
> >> So, I was surprised when I saw that Matthew picked interoperability
> >> with code that uses set-car!/set-cdr! (very little importance IMHO)
> >> over interoperability with the rest of the PLT code base.
> >
> > I imagined that users would be too unhappy with that level of
> > non-conformance, but it sounds like I may have been wrong.
> >
> > Does anyone here want PLT Scheme's R6RS support to include `(rnrs
> > mutable-pairs)'?
> Yes.
> 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

 Does anyone actually use (and expect to continue to use) the `(rnrs
 mutable-pairs)' library in PLT Scheme's R6RS?


Posted on the users mailing list.