An hour ago, Andre van Tonder wrote:
> On Fri, 29 Apr 2011, John Cowan wrote:
>
> >> WG2 will have explicit renaming only.
> >
> > If you're curious: explicit renaming was voted up 4-0; syntactic
> > closures voted down 1-3; and syntax-case tied with 3-3 (with one
> > vote for sending it to a future WG), which means it failed.  There
> > were 11 WG members at the time, of which 2 did not vote at all.
>
> I hope the committee took into account that for systems like Racket
> and Chez that are based on a native psyntax-type macro
> implementation, providing ER macros would adversely affect the
> complexity class of such macros, because in these systems an extra
> code walk is necessary to fully unwrap each input to the ER
> transformer.

It's more than that for Racket, since all expressions are wrapped, and
an implementation of a macro transformer that deals with just plain
lists means that function application (`#%app', an important Racket
feature) becomes unhygienic.

(Obviously there's the question of "how can anyone sane suggest a
system with several different function applications".  Racket has
several answers to that in the form of features that would be
otherwise impossible.)

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

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