Re: macros, procedure->macro

[Dirk Herrmann <dirk@sallust.ida.ing.tu-bs.de>]

On 9 Jul 2002, Neil Jerram wrote:

>     Dirk> If all results are positive, I will go ahead and remove the support
>     Dirk> for "macros" from guile.  After that, I will take a close look at "acros"
>     Dirk> and we will play a similar game with "acros" again...
> 
> Before doing this, I think we need to state clearly when macro
> expansion will happen in the future Guile.
[...]
> (As far as I understand, the options are just after reading and just
> before memoization, but just-after-reading makes recursive macro
> definitions difficult, and just-before-memoization leads to rather
> lame execution-dependent expansion.

Hmmm, I don't quite understand you here - to me it seems that the big
difference is whether macro-expansion happens during execution, or before
execution.  If macro-expansion happens before execution, you could
basically have one big step "macro expansion + memoization/compilation"
which should cover both the just-after-reading and the
just-before-memoization options.  Sure, this big step is better separated
into different tasks, but that can be decided later.  Currently my focus
is on separating the big step from execution.

> Obviously, by definition, the exact timing only matters for
> non-hygienic macros; but my assumption is that an awful lot of people
> want non-hygienic macros.)

Could you give some examples for situations where the exact timing is
important?

Best regards,
Dirk Herrmann


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