Re: Declaring Lisp function types

[Joost Kremers <joostkremers@fastmail.fm>]

On Tue, Mar 26 2024, Andrea Corallo wrote:
> Andrea Corallo <acorallo@gnu.org> writes:
>> 1:
>>
>> (defun sum (a b)
>>   (declare (function (integer integer) integer))
>>   (+ a b))
>>
>> 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.
>>
>> Maintainers WDYT?

I'm not a maintainer, so ignore this message if you like, but having just reread
the info node on `declare`, 2 doesn't make sense to me. `declare` takes an
argument SPECS, where "[e]ach element in SPECS should have the form ‘(PROPERTY
ARGS...)’". Using `type` as PROPERTY makes sense, but if its argument can be
`(function in-types out-type), you'd expect that it could also be `(macro
in-types out-type)`, possibly among other options (`closure`? `command`?).

For similar reasons, using `function` as the PROPERTY is also a bit strange.
(Unless this form would be restricted to actual functions? I didn't read that
anywhere in the thread.)

So `type` seems to make sense. Or, if that is too generic a term, why not use
`signature` instead?

-- 
Joost Kremers
Life has its moments