On Thu, 26 May 2011 10:02:06 -0400, Jim Wise <jwise@draga.com> wrote:

> (And so it's clear, I don't have a dog in this fight -- I'm not an
> implementor, just a user who finds R6RS, as implemented in Chez and
> Racket, more pleasant to use than R5RS or R4RS, and worries that many of
> the features that made it so are in danger of being thrown out with the
> bathwater.)

The idea is that WG1 will provide a core language upon which WG2 may
subsequently develop a proper enhancement of R6RS. From my perspective,
the current issue with WG1 that we still have not adequately addressed is
how to ensure an attractive core language that satisfies people who do
want a more simple language while at the same time remaining *compatible*
with the language that will inevitably result from the WG2 efforts.
Therein lies the problem. It would be easy to fragment the two languages
apart. However, the WG1 has a difficult job precisely because the end goal
is still one single language. If WG1 introduces some semantics or feature
that "steps on the toes" of WG2, it will be very difficult for WG2 to do a
good job. On the other hand, it cannot simply become WG2.

Unfortunately, this particular issue does not receive as much attention as
I think it deserves. People may feel that WG1 should either be backwards
compatible with R6RS or should have no need to concern itself with
backwards compatibility with R6RS. I think the issue is more difficult
than that. WG1 must remain compatible with existing standards specifically
to enable WG2 to do its job. This is a more subtle and difficult thing to
achieve.

Others will disagree with my interpretation of the charters for the two
groups, we can split hairs on this, but the bottom line is that these
efforts are meant to unify Scheme around a unified standard, acknowledging
the diverse needs of the people who use Scheme. The key term there is
UNIFY. We cannot alienate R6RS users, and neither can we alienate those
who still remain opposed to R6RS. This is especially important for WG1,
since WG1 fuels WG2's efforts, and if we negligently resist the changes in
R6RS such that we make things incompatible or inherently difficult for
those sorts of implementations, we are doing ourselves no favors.

	Aaron W. Hsu

--
Programming is just another word for the lost art of thinking.

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