From: Andrea Corallo <acorallo@gnu.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 73626@debbugs.gnu.org
Subject: bug#73626: 30.0.91; Type specifiers of functions
Date: Wed, 23 Oct 2024 18:29:06 -0400 [thread overview]
Message-ID: <yp1ttd2sbbh.fsf@fencepost.gnu.org> (raw)
In-Reply-To: <86msjkxdf5.fsf@gnu.org> (Eli Zaretskii's message of "Fri, 04 Oct 2024 15:25:50 +0300")
Hi Eli,
sorry for being late on this.
Eli Zaretskii <eliz@gnu.org> writes:
> To reproduce:
>
> emacs -Q
> C-h f sort-lines RET
>
> (That particular function is just an example, basically, any function
> should do.)
>
> Observe in the *Help* buffer:
>
> sort-lines is an autoloaded interactive byte-code-function in
> ‘sort.el’.
>
> (sort-lines REVERSE BEG END)
>
> If sort.el was native-compiled, you will see this instead:
>
> sort-lines is an autoloaded interactive native-comp-function in
> ‘sort.el’.
>
> (sort-lines REVERSE BEG END)
>
> So far so good, but in a long-running Emacs session I see this:
>
> sort-lines is an autoloaded interactive native-comp-function in
> ‘sort.el’.
>
> (sort-lines REVERSE BEG END)
>
> Inferred type: (function (t t t) t) <<<<<<<<<<<<<<<<<<<<<<
>
> and sometimes this:
>
> bobp is a primitive-function in ‘src/editfns.c’.
>
> (bobp)
>
> Declared type: (function nil boolean) <<<<<<<<<<<<<<<<<<<<<
>
> These Declared/Inferred type thingies are not documented anywhere,
> AFAICT. If one looks really hard, one can find in "Declare Form" the
> description of "(ftype TYPE &optional FUNCTION)", but still nothing
> about declared/inferred. I see in help-fns.el:help-fns--signature
> that we call comp-function-type-spec to get this information, and the
> doc string of comp-function-type-spec says:
>
> Return the type specifier of FUNCTION.
>
> But there are no matches for "type specifier" anywhere in the ELisp
> manual, and comp-function-type-spec itself is not documented there.
>
> Even after looking and finding all those pieces of the puzzle, the
> overall picture is not clear. The following is missing, and should be
> documented in the ELisp manual:
>
> . what is the importance of inferred vs declared type
The user get to know that the function type was computed by the compiler
or manually declared by the user.
> . how to read the type specifiers,
The format is the same described for type declarations ((elisp)Top >
Functions > Declare Form).
I agree we should probably better document this somewhere else, probably
in Lisp Data Types?
> and in particular what do those "t" members mean,
t is a type documented (elisp)Top > Lisp Data Types > Type Hierarchy
> and more generally, which forms can appear in the
> car of the cons cell returned by comp-function-type-spec
Hope I answered before.
> . why "C-h f" shows this information only for some functions and not
> for others, and what is the significance of that
C-h f does not show the inferred type if the functions has still to be
native compiled and loaded, the reason is simply that is the native
compiler computing the type.
> Bottom line: we decided that this information is important enough to
> show it in the *Help* buffer, so we should explain its arcane parts to
> make them useful.
Agree. Is '(elisp)Top > Lisp Data Types' a reasonable place for that?
Otherwise where should we do it?
Thanks
Andrea
next prev parent reply other threads:[~2024-10-23 22:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-04 12:25 bug#73626: 30.0.91; Type specifiers of functions Eli Zaretskii
2024-10-19 7:01 ` Eli Zaretskii
2024-10-23 22:29 ` Andrea Corallo [this message]
2024-10-24 15:47 ` Eli Zaretskii
2024-10-25 9:35 ` Andrea Corallo
2024-10-25 10:19 ` Eli Zaretskii
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