Andre van Tonder wrote:

> So unless the performance problem can be ameliorated, giving a practical
> and truly portable implementation based on SYNTAX-RULES, there may be a
> case for withdrawal.  Possible reasons for keeping it alive regardless
> of current performance are its conceptual simplicity (this remains a pure
> rewriting system, without the phase separation complexities of
> syntax-case), and the possibility that future additions to SYNTAX-RULES
> may enable a more efficient implementation (however, it seems more likely
> that something like SYNTAX-CASE will become part of the standard).

I'm less than thrilled with syntax-case, mainly because it is so poorly
specified.  In fact there is no specification, just a bunch of neat
examples of what you can do with it.  But as an example I haven't seen
any discussion of what is supposed to happen if a syntax transformer
references a run-time variable.  I've found the implementation and the
description of syntax-case hard to understand, and not at all intuitive.
  The "portable" implementation is far from a direct drop-in to an
existing implementation that aready supports macros, and figuring out
what needs to be changed is non-trivial.  I've started studying the
implementation more than once, and decided I decided I have more
important things to do.

On the other hand a syntax library like srfi-53 should be much easier to
incorporate, even if I have to add a few new primitives.
--
	--Per Bothner
xxxxxx@bothner.com   http://per.bothner.com/