On 29 Oct 2009, at 7:37 pm, John Cowan wrote:

> Alaric Snell-Pym scripsit:
>
>> First, some definitions. I think we can take it as a given that a
>> desirable feature of a macro system is that macro expansions should
>> be
>> decidable "before run time". It's overspecifying to call that
>> "compile
>> time", "link time", or "tea time";
>
> I just call it "macro-expansion time".  But no, there is a small but
> vocal minority that is absolutely opposed to this notion.

Aye... politics, eh? ;-)

>
>> That desire for being able to expand all the macros away before run
>> time, revealing a semantically equivalent program without any macros
>> in it (and from which all the macro definitions can therefore be
>> stripped or ignored), is part of what makes fexprs bad.
>
> Unfortunately, this argument is easily caricatured:
>
> # That desire for being able to expand all the typecases away before
> # run time, revealing a semantically equivalent program without any
> # polymorphism in it, is part of what makes dynamic typing bad.

Which is also a valid argument, albeit one that doesn't stand up so
well when considered in context ;-)

> Indeed, that's what alexpander is.  Alexpander is only written in
> Scheme
> for Al* Petrofsky's convenience: it could perfectly well be written in
> Cobol (only with extra added pain) and would work in exactly the
> same way.

For painful interpretations of "perfectly well", indeed!

ABS

--
Alaric Snell-Pym
Work: http://www.snell-systems.co.uk/
Play: http://www.snell-pym.org.uk/alaric/
Blog: http://www.snell-pym.org.uk/archives/author/alaric/




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