Re: Declaring Lisp function types

[Adam Porter <adam@alphapapa.net>]

Hi Andrea, et al,

> I'd like to progress on this but in order to do that we should pick a
> syntax.
> 
> Of the three most discussed syntaxes in this thread my order of
> preference is (by examples):
> 
> 1:
> 
> (defun sum (a b)
>   (declare (function (integer integer) integer))
>   (+ a b))

Please do not use this syntax.  As I've said on the list at 
<https://lists.gnu.org/archive/html/emacs-devel/2024-02/msg00790.html> 
and 
<https://lists.gnu.org/archive/html/emacs-devel/2024-02/msg00815.html>, 
and in this bug report 
<https://debbugs.gnu.org/cgi/bugreport.cgi?bug=69521>, and again on the 
list in this separate thread, as I was instructed 
<https://lists.gnu.org/archive/html/emacs-devel/2024-03/msg00118.html>, 
that would preclude the possibility of allowing DECLARE-FUNCTION forms 
to be placed inside DEFUNs' DECLARE forms as:

   (declare (function ...))

For some reason, I can't seem to get a response to that idea, either 
affirmative, negative, or neutral.  But I would ask that my proposal at 
least be considered and addressed before moving forward with that syntax 
for this other purpose.

> 2:
> 
> (defun sum (a b)
>   (declare (type (function (integer integer) integer)))
>   (+ a b))
> 
> 3:
> 
> (defun sum (a b)
>   (declare (type (integer integer) integer))
>   (+ a b))
> 
> For the reasons I've already expressed: 1 I like it, 2 I'm okay with it,
> 3 I very much dislike it.

Forgive me if I've missed it, but why do you dislike #3?  It seems 
concise and descriptive: it is DECLAREing the DEFUN's TYPEs, just as:

   (declare (debug ...))

DECLAREs the DEFUN's DEBUG instrumentation.  Whereas including 
"function" in the form seems redundant and occupies several extra 
characters.  The DECLARE form is specifically about the DEFUN, so what 
other TYPEs would it be about?

Thanks,
Adam