From: akater <nuclearspace@gmail.com>
To: "Basil L. Contovounesios" <contovob@tcd.ie>
Cc: emacs-devel@gnu.org
Subject: Re: defmacro with built-in gensym declaration and initialization
Date: Wed, 20 Jan 2021 19:28:06 +0000 [thread overview]
Message-ID: <878s8n76ih.fsf@gmail.com> (raw)
In-Reply-To: <87turbiuvr.fsf@tcd.ie>
[-- Attachment #1: Type: text/plain, Size: 2026 bytes --]
"Basil L. Contovounesios" <contovob@tcd.ie> writes:
> IMO, this minor convenience is insufficient motivation for
> conflating/complicating a macro's global arglist, i.e. its arity,
> calling convention, etc., with utilities for its local body. Is there
> some other motivation? Am I missing something?
My motivation mostly comes from CL where complicated lambda lists are
not considered an issue, and it didn't come to my mind it could be an
issue for Emacs Lisp users. In particular, &gensym does indeed follow
the design of &aux, described below as “hideous” (another surprise). I
use &aux regularly, and I find it a nice addition as it reduces the
nesting depth of defun and defmacro forms. &gensym does that and saves
some boilerplate on top of it, I tried it in real life macros, found it
useful, and that's pretty much it.
> conflating/complicating a macro's global arglist, i.e. its arity,
What's the arity of defmacro? This form already allows any number of
arguments so as far as I can see adding another keyword does not change
arity. Calling convention is backwards compatible. Again, Common Lisp
implementations are allowed to introduce their own lambda list keywords
so I didn't (and still don't) think extending lambda-list keywords set
is a big deal.
> Why not provide handy gensym/once-only local conveniences for macro
> authors instead (some of which already exist in one form or another,
> e.g. macroexp-let2, inline-letevals, and org-with-gensyms)?
I don't have much experience with macroexp-let2 which on the first
glance looks like an overcomplicated once-only that is mostly relevant
for functions that are meant to be byte-compiled. Since we're moving to
natively compiled Elisp, I was thinking it's going to become less
relevant in near future, and &gensym covers most use cases of once-only.
Again, org-with-gensyms is precisely something that's being replaced
here with an alternative that is less verbose and has a decreased
nesting depth.
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 865 bytes --]
next prev parent reply other threads:[~2021-01-20 19:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 8:15 defmacro with built-in gensym declaration and initialization akater
2021-01-20 13:46 ` Basil L. Contovounesios
2021-01-20 15:09 ` Stefan Monnier
2021-01-20 16:47 ` Robin Tarsiger
2021-01-20 19:28 ` akater [this message]
2021-01-20 20:55 ` Basil L. Contovounesios
2021-01-21 19:34 ` akater
2021-01-21 20:50 ` Stefan Monnier
2021-01-21 20:50 ` Basil L. Contovounesios
2021-01-21 21:05 ` Stefan Monnier
2021-01-21 21:23 ` Basil L. Contovounesios
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=878s8n76ih.fsf@gmail.com \
--to=nuclearspace@gmail.com \
--cc=contovob@tcd.ie \
--cc=emacs-devel@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.