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Re: issue DEFINING-MACROS-NON-TOP-LEVEL, version 5
- To: Jon L White <email@example.com>
- Subject: Re: issue DEFINING-MACROS-NON-TOP-LEVEL, version 5
- From: firstname.lastname@example.org (Sandra J Loosemore)
- Date: Fri, 30 Dec 88 14:33:00 MST
- Cc: email@example.com, firstname.lastname@example.org
- In-reply-to: Jon L White <email@example.com>, Wed, 21 Dec 88 20:40:59 PST
> Date: Wed, 21 Dec 88 20:40:59 PST
> From: Jon L White <firstname.lastname@example.org>
> I'm not at all comfortable tying in the definition of "toplevel" to READ.
> In particular, lots of so-called top-level forms are not explicitly read
> in, but rather are constructed up by macros which return something like
> `(PROGN (DEFUN ...) (DEFMACRO ...) ...<whatever>...)
The definition in the proposal is intended to cover this case; it does say
that the expansion of a top-level macro is also considered to be top-level.
Perhaps I can word this section better. How about:
- A form read by COMPILE-FILE from the input file is a top-level form.
- Forms within the body of a top-level PROGN or EVAL-WHEN are also
- The expansion of a top-level macro call is also a top-level form.
To me, this kind of recursive definition seems much simpler than
saying "null lexical environment" and then listing a zillion
exceptions. Top-level implies null lexical environment, but the
reverse is not true.
> re: Specify that top-level forms in a file being
> compiled are guaranteed to be processed sequentially, but the order in
> which subforms of a top-level form are processed by the compiler is
> explicitly left unspecified.
> I don't understand the motivation for saying anything at all about the
> order of processing the subforms; in particular, it conflicts with a
> perceived requirement that if (PROGN (A) (B)) is at toplevel, then (A)
> and (B) must be processed " at toplevel" and **in order**.
Oops, I guess I lost the rationale for this when I revised the
proposal. It's to allow compilers to perform certain kinds of
source-to-source transformations that may reorder subforms. In any
case, I think it's reasonable to specify that the bodies of top-level
PROGNs and EVAL-WHENs are processed in order, and the proposal should be
more explicit about that.