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Re: [Scheme-reports] [wg2] in support of single-arity procedural syntax transformers

On Wed, May 11, 2011 at 06:06:15PM +0200, Andy Wingo wrote:
> On Wed 11 May 2011 17:25, Peter Bex <Peter.Bex@x> writes:
> > The procedures or syntactic forms er-macro-transformer,
> > sc-macro-transformer, syntax-case and syntax-rules already
> > hide the implementation details well enough.
> That is true for all but syntax-case.

Of course, you're right.  But then that doesn't matter, if R7RS
only specifies what happens when you do

(define-syntax (syntax-rules ...)) or
(define-syntax (er-macro-transformer ...)) that doesn't shut out
the possibility of syntax-case, does it?

The other way around it does shut out implementations like Chicken
where the "er-macro-transformer" line is more or less optional
because that's its native system.

> You might decide that you don't like it, and that's cool, no
> need to implement it.

Yes, but you do need to restructure things unneccessarily then.
Of course it's a small change and shouldn't break programs
written with syntax extensibility in mind, but it *will* break
some programs I'm sure.

"The process of preparing programs for a digital computer
 is especially attractive, not only because it can be economically
 and scientifically rewarding, but also because it can be an aesthetic
 experience much like composing poetry or music."
							-- Donald Knuth

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