[racket-dev] [plt] Push #25466: master branch updated

What is 'p' in this example?

On Wednesday, October 17, 2012, Sam Tobin-Hochstadt wrote:

> On Tue, Oct 16, 2012 at 7:55 PM, Stephen Bloch <bloch at adelphi.edu<javascript:;>>
> wrote:
> >>> Another data point: If "define/match" expands to a "define" of a
> procedure
> >>> that dispatches to a set of implementations based on a pattern-match of
> >>> actual arguments... then the name is exactly what I'd expect for such a
> >>> feature in a Scheme dialect.
> >>
> >> That is, in fact, exactly what it does.
> >
> > Cool!  My students have been writing code that way for years, and I've
> been telling them "There are languages in which that would work, but Scheme
> isn't one of them."
> >
> > (define (swap (make-posn x y))
> >     (make-posn y x))
>
> The syntax looks like:
>
>   (define/match (swap p)
>      [(posn x y) (posn y x)])
>
> --
> sam th
> samth at ccs.neu.edu <javascript:;>
> _________________________
>   Racket Developers list:
>   http://lists.racket-lang.org/dev
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