[R6RS] SYNTAX-CASE

[dyb at cs.indiana.edu]

> I don't think that we have agreed on including SYNTAX-CASE as is. 
> I was pushing in favor of a general pattern matching mechanism that could be
> applied to macros too. 

Since my October 19 note, where I laid out some of the difficulties,
I've done some research on existing general-purpose matchers and thought
really hard about how we might make this work.  While I still agree that a
unified matcher is a desirable goal in principle, I have become convinced
that it's highly unlikely that we can come up with a general-purpose
matcher that also doubles adequately as a domain-specific matcher for
syntactic abstraction.  At best, we could specify a straightforward
translation from something like syntax-case into a general-purpose
matcher, assuming some level of similarity.  Furthermore, given the
variety of matchers out there, I suspect we'd even have trouble agreeing
on a general-purpose matcher independently of syntactic abstraction.

I therefore propose that we standardize on syntax-case pretty much as
it is.

Kent