On Mon, Dec 4, 2023, 8:20 AM Eli Zaretskii <
eliz@gnu.org> wrote:
> From: Lynn Winebarger <owinebar@gmail.com>
> Date: Mon, 4 Dec 2023 07:35:48 -0500
> Cc: Richard Stallman <rms@gnu.org>, schwab@linux-m68k.org,
> emacs-devel <emacs-devel@gnu.org>
>
> Elisp will happily evaluate the expression
> (if . ( t . (nil . (t . nil))))
>
> Would you, or anyone, say that reflects some flaw in the design of the "if" form?
No, but if someone writes such 'if' forms, I will ask them to rewrite
them.
IOW, the fact that the Lisp reader will happily read something does
not mean it is easily understandable by humans, or should freely be
used in Emacs.
Right, it's a style issue.
The issue Richard raised that I've begun to appreciate is that backquote is redefined in the context of patterns in a way that is not compatible with its definition everywhere else. I don't think the same could be said of the "," and ",@" read-syntax or symbols, because those symbols are not defined as macros themselves, only as auxiliary syntax in the context of quasiquotation. It should be fine to incorporate them as auxiliary syntax in the context of a destructuring macro, preferably with a reasonably consistent semantics.
Lynn