Re: [Chicken-hackers] [PATCH] Fix meta evaluation (so that require-extension-for-syntax works properly)

[John Cowan]

Peter Bex scripsit:

> (currently all the macro environments are shared between all modules
> and there's only one level, which means you can't import a module for
> syntax which itself imports another module for syntax and have it see
> a clean environment).

Does it matter?  In Racket, you can have identifiers defined differently
at different levels, but in other R6RS systems (well, maybe not Chez, I
don't know Chez) the only "cleanness" you actually get is that identifiers
can be defined at some levels and not at others.

In exchange for this very dubious benefit, we have a situation in
which implementations are allowed to ignore phase information if it
is provided, but equally allowed to insist on its presence.  (If
conflicting definitions were allowed, obviously phasing information
would have to be explicit, as it is in Racket.)

I hope that in R7RS-large we are going to do without phasing declarations
and force the implementation to either put everything in one big phase
(and so what if some identifiers are defined when they are not needed)
or figure out the phases itself based on the library dependency graph.

-- 
Barry thirteen gules and argent on a canton azure           John Cowan
fifty mullets of five points of the second,             address@hidden
six, five, six, five, six, five, six, five, and six.
        --blazoning the U.S. flag           http://www.ccil.org/~cowan