Re: Distinguishing `consp` and `functionp`

[João Távora]

On Mon, Jan 29, 2024 at 4:28 PM Stefan Monnier <monnier@iro.umontreal.ca> wrote:
>
> > I don't think there is much space for philosophy or debate in noting
> > for example, that a list as lambda won't get byte-compiled like a
> > true lambda form.
> >
> > (byte-compile '(let ((bla (lambda () (+ 42 42))))
> >                  (funcall bla))) ;; -> (byte-code "\300\211 \207" [#[0
> > "\300\207" [84] 1]] 2)
> >
> >
> > (byte-compile '(let ((bla '(lambda () (+ 42 42))))
> >                  (funcall bla)));; -> (byte-code "\300 \207" [(lambda
> > nil (+ 42 42))] 1)
>
> While it's in the vicinity, this is not directly related to my patch.

I know, your patch doesn't address this.  But if I understand
correctly it makes at least functionp return nil for the second one.
Or at least makes way for it.  And that's a plus in my book.

>
> >>     commit 9228fd983bb9e71d44d406433a46495b22640801
> >>     Author: Marten Lienen <marten.lienen@gmail.com>
> >>     Date:   Mon Jan 22 11:08:44 2024 +0100
> >>
> >>         * yasnippel.el (yas-buffer-local-condition): Check functionp 
> >> before consp to allow closures
> [...]
> > Stefan's patch moves us in the right direction if just for the guidance
> > it gives to ignorant Lispers like the one who introduced that bug circa 
> > 2009.
>
> FWIW, the bug fixed by the above commit was introduced a few days
> earlier by yours truly,

Alright.  I wouldn't be surprised if I wasn't passing lists as lambdas
around in that extension.  I used to do that, and saw many fall prety
to this, when their lisps allow it.  The result is harder to debug code
and harder to instrument.