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List:       racket-dev
Subject:    [racket-dev] built-in syntax-parse syntax class for "match" patterns?
From:       samth () ccs ! neu ! edu (Sam Tobin-Hochstadt)
Date:       2011-03-31 12:22:52
Message-ID: AANLkTikZ-CrTWBuOLRunT12sjk18y0RKoj1c8+ArOZDw () mail ! gmail ! com
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On Thu, Mar 31, 2011 at 5:22 AM, Carl Eastlund <cce at ccs.neu.edu> wrote:
> Match patterns are macro-extensible. ?Just about any s-expression is a
> potential match pattern. ?I don't think there's anything for a syntax
> class to discern, just accept whatever someone puts there, and trust
> expansion to sort out any errors.

Technically, this isn't correct, because the syntax class could do
what `match' does, and look for uses of the `match' extension
mechanisms.  However, there aren't any syntax classes that do this.
I've experimented in the past with trying to write such a syntax class
for the implementation of `match', but it hasn't been finished, and
may require further extensions to `syntax-parse' before that happens.

When it does, I'll try to remember to export a syntax class as a
recognizer for others to use.  In the meantime, I recommend following
Carl's advice.

sam th

> 
> Carl Eastlund
> 
> On Thu, Mar 31, 2011 at 3:20 AM, John Clements
> <clements at brinckerhoff.org> wrote:
> > If I want to use syntax-parse to define a syntactic form that expands into a use \
> > of 'match', is there a built-in syntax class that recognizes 'match' patterns? \
> > Unfortunately, searching for 'match' and 'pattern' in the syntax-parse docs isn't \
> > so helpful... :). 
> > John
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> 



-- 
sam th
samth at ccs.neu.edu


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