[racket] Unexpected error extracting value from request bindings.

From: Eli Barzilay (eli at barzilay.org)
Date: Mon Aug 1 12:28:51 EDT 2011

Five minutes ago, Hendrik Boom wrote:
> On Mon, Aug 01, 2011 at 01:08:27AM -0400, Neil Van Dyke wrote:
> > 
> > Esoterica #2: You'll see functions like "gensym" and "gentemp" in
> > some old Lisp dialects, and they will be used mostly to get around
> > problems of non-hygienic macros in that particular dialect.  I
> > don't recall seeing them used in real Racket or Scheme code,
> > however, probably because those languages have hygienic macros.
> I've used them extensively in programs doing theorem proving on
> formulas involving quantifiers.  This had noting to do with macros,
> hygienic or not.

That's really the same use as macros: it's the easiest way to get a
"completely fresh" value, which is frequently needed in such a world
(and can get hairy if you're restricted in a pure world).  IMO
uninterned symbols are actually a little *worse* for that purpose,
because besides the freshness, they have this confusing feature of
being printed like other symbols.

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

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