On Sat, 05 Sep 2009 18:17:01 -0400, John Cowan <[email protected]> wrote:
> Thomas Lord scripsit:
>
>> Would one approach be better than the other? I would only say that
>> first class environments are a natural fit for most interpretation
>> strategies, that they can be given a nice clean semantics, and that
>> they are a more general purpose tool than hygienic macros.
>
> I'd like to hear other people's views on this.
I would argue that environments are something entirely separate from
macros, and that we shouldn't conflate the two issues. Macros are for
transforming expressions to other expressions, and can be used to build
modules that control visibility of bindings, but they are compile time
entities, whereas environments are first-class encapsulations of bindings
that can be used and manipulated at run time to do things. At least,
that's how I think of environments. I've never really used environments
that much, but I can see places where I would use them, rather than
macros, and there are certainly places where I would use macros instead of
environments. Unless we're talking about two different things, here?
I think we should have both.
Aaron W. Hsu
--
Of all tyrannies, a tyranny sincerely exercised for the good of its
victims may be the most oppressive. -- C. S. Lewis
_______________________________________________
r6rs-discuss mailing list
[email protected]
http://lists.r6rs.org/cgi-bin/mailman/listinfo/r6rs-discuss
