[racket-dev] [plt-scheme] Bug or misuse? match-expander ids not properly working (patch)

20 minutes ago, J. Ian Johnson wrote:
> That behavior would be really spooky to me. I would expect binding
> positions to not depend on any environmental information.

(It's still the same, only the definition of what is a binding
position is a bit different.)


> Perhaps have an (id _) form that would allow putting your special
> identifiers there.

And, Carl Eastlund wrote:
> If we add some kind of id expanders for match patterns, we need to
> add a way for pattern variables to shadow these names if the author
> really wants to.   Otherwise, every id expander defined eats up more
> namespace that match variables cannot bind.
> 
> We already have this issue with _ and ..., but at least that's a
> known set of constant size.

Some (id <name>) be possible, but definitely an overkill for the
purpose of `null' etc.  Like I said, there should be *very* few of
them in `#lang racket'.  The rest are for your own convenience, as in
Madoka's case (and in a few cases I ran into).  I could obviously
define and provide a match expander for `x' in my library that you'll
want to use -- but that's the same as providing you with my own `if'.

The bottom line is that if this change is done, then such an `id' form
would not be necessary -- either it's for obvious names (the few that
are done in the library), or for names that you defined which you're
supposed to know about.

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!