[r6rs-discuss] [scheme-reports] Scheme pattern matching & R*RS
cowan at mercury.ccil.org
Fri Jan 21 09:57:19 EST 2011
David Rush scripsit:
> Given the wide variety of things that get affected by pattern
> matching, while I admit that this is possible, I don't think it is
> advisable. Pattern matching is a powerfully expressive mechanism - if
> we are going to have it we should properly percolate its power all the
> way through the language.
You are making the best the enemy of the good, and saying "Because we
won't have deeply integrated pattern matching in R7RS, we shouldn't have
standardized pattern matching available on implementations that choose
to provide it." The whole idea of WG2 is to provide a large battery
of optional modules, such that if implementations choose to provide a
feature, users can rely on *how* it is provided, and thus write programs
that are portable across sufficiently powerful implementations.
> Are we really willing to go here? I'd be up for it, but I thought that
> the community was shying away from radical changes through
> standardization, and that deep innovation in the Scheme community was
> supposed to be led by implementations.
Quite so, for WG1. WG2 tracks implementations where they exist,
and attempts to provide them where they don't. This is a case where
implementations exist; all I've done is relabel them, which in a language
with modules is a fairly trivial thing to do.
One Word to write them all, John Cowan <cowan at ccil.org>
One Access to find them, http://www.ccil.org/~cowan
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And thus to Windows bind them. --Mike Champion
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