On Wed, Nov 26, 2008 at 9:01 AM, Matthew Flatt <<a href="mailto:mflatt@cs.utah.edu">mflatt@cs.utah.edu</a>> wrote: <div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Just to be clear, this does not answer my question. You've addressed a more abstract question "What should be the relationship between the PLT Scheme implementation and standardized dialects of Scheme?" It's fine to answer that question, but it's not the question that currently interests me.</blockquote><div> Hi Matthew, I do not use mutable pairs either.  Besides answering your question, I do have a request and it is that whatever approach you choose, please do whatever you can (I know you already do - but I have to stress it) to keep compatibility. Quite a few planet packages I tried/used do not even install with PLT4, and there is no way to know from planet whether a package has been vetted.  Users bear the grunt of figuring things out the hard way here. As you know a healthy 3rd party code repository is important to attract and build developer community, breaking compatibility is thus costly, especially for industry developers.  For me, the cost of PLT4 is high(er than necessary). There of course will be tension with the need to innovate.  But if building a viable community is part of PLT's goal, then the decision should involve more than just technical merits.  I know I am preaching to the choir, but I feel it needs to be mentioned.  Thank you for all of the hard work in making PLT such a wonderful platform! :) Thanks, yc </div></div>