Sv: Subrp returns nil for function objects and symbols? Is this a bug or me misunderstanding it?

[arthur miller <arthur.miller@live.com>]

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> > (subrp 'car) => nil
> > (subrp #'car) => nil
> > (subrp '+) => nil
> >
> > (subrp (symbol-function 'car)) => t
> >
> > According to the doc, subrp should tell me if "OBJECT" is a built-in
> > function or not. I would expect "car" to be that, since car is implemented
> > in the C source (in data.c).
> >
> > I also get the same behavior for compiled-function-p.
> >
> > Is it not valid to pass a symbol and function objects to those two
> > functions? Can we in that case clarify in the doc string expected
> > value(s) for OBJECT?
>
> At least it's documented in the Elisp manual (info "(elisp) What Is a
> Function"):

Yes. I see it now. I was just looking at function docs previously. Thanks.

>   Unlike ‘functionp’, the next functions do _not_ treat a symbol as its
>   function definition.
>
>    -- Function: subrp object
>        This function returns ‘t’ if OBJECT is a built-in function (i.e., a
>        Lisp primitive).
>
>             (subrp 'message)            ; ‘message’ is a symbol,
>                  ⇒ nil                 ;   not a subr object.
>             (subrp (symbol-function 'message))
>                  ⇒ t

Ok, they are explicit it does not look at function slot of a symbol itself
(2.4.15). However, I find the documentation a bit vague or perhaps outdated. In
particular regarding the "built-in" type. Perhaps this function
historically meant something else than how it works today (I think it did). I
guess built-in used to mean "implemented in C core", but since the native
compiler come in, it seems to rapport any machine-code compiled function as
"subr":

(defun test-fn () (message "hi"))
(native-compile 'test-fn)
(subrp (symbol-function 'test-fn)) => t

In other words, perhaps manual should be updated to say something along the line
that subrp tells if function is a function compiled to machine code. I see now
also that compiled-function-p repports if a function is both byte-code compiled
and machine-code compiled as "compiled" so those are not equal.
________________________________
Från: Stephen Berman <stephen.berman@gmx.net>
Skickat: den 13 augusti 2024 13:08
Till: arthur miller <arthur.miller@live.com>
Kopia: emacs-devel@gnu.org <emacs-devel@gnu.org>
Ämne: Re: Subrp returns nil for function objects and symbols? Is this a bug or me misunderstanding it?

On Tue, 13 Aug 2024 09:22:01 +0000 arthur miller <arthur.miller@live.com> wrote:

> (subrp 'car) => nil
> (subrp #'car) => nil
> (subrp '+) => nil
>
> (subrp (symbol-function 'car)) => t
>
> According to the doc, subrp should tell me if "OBJECT" is a built-in
> function or not. I would expect "car" to be that, since car is implemented
> in the C source (in data.c).
>
> I also get the same behavior for compiled-function-p.
>
> Is it not valid to pass a symbol and function objects to those two
> functions? Can we in that case clarify in the doc string expected
> value(s) for OBJECT?

At least it's documented in the Elisp manual (info "(elisp) What Is a
Function"):

  Unlike ‘functionp’, the next functions do _not_ treat a symbol as its
  function definition.

   -- Function: subrp object
       This function returns ‘t’ if OBJECT is a built-in function (i.e., a
       Lisp primitive).

            (subrp 'message)            ; ‘message’ is a symbol,
                 ⇒ nil                 ;   not a subr object.
            (subrp (symbol-function 'message))
                 ⇒ t

Steve Berman

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