[racket-dev] built-in syntax-parse syntax class for "match" patterns?

From: Sam Tobin-Hochstadt (samth at ccs.neu.edu)
Date: Thu Mar 31 08:22:52 EDT 2011

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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