From: Doug Evans <dje@sebabeach.org>
To: cgen@sourceware.org
Subject: Opinions wanted: What should (.list pmacro-name 42) do?
Date: Thu, 20 Aug 2009 17:30:00 -0000 [thread overview]
Message-ID: <4A8D8838.9090708@sebabeach.org> (raw)
Hi.
What should the output of
(define-pmacro (foo a) (add a 1))
(.list foo 42)
be?
Currently the result is (<pmacro> 42)
where <pmacro> is the pmacro object for "foo".
It's not ideal because it means that a pmacro object "escapes"
pmacro-processing and can be seen by, for example, rtl compilation.
However, it's not that unexpected. The user asked for a list containing
two objects, the pmacro and 42.
This is akin to saying (list + 42) in Scheme.
We *could* have the pmacro evaluator re-examine the result and if it
sees (<pmacro> mumble) then re-expand it. That's what we do for symbols
today (i.e. if the result of pmacro-expansion is a symbol that names a
pmacro, we re-evaluate it), but that has problems, e.g.
http://sourceware.org/ml/cgen/2009-q3/msg00052.html
and I'm leaning toward removing that behavior.
It's not clear to me what The Right Thing to do is.
Opinions?
next reply other threads:[~2009-08-20 17:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-20 17:30 Doug Evans [this message]
2009-08-20 17:44 ` Doug Evans
2009-08-20 18:24 ` Jim Blandy
2009-08-21 4:30 ` Doug Evans
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