Eli Zaretskii <eliz@gnu.org> writes:

>> From: Andrea Corallo <acorallo@gnu.org>
>> Cc: 73626@debbugs.gnu.org
>> Date: Wed, 13 Nov 2024 19:27:52 -0500
>>
>> Okay this is what I'm working on.  I felt the need to add a more general
>> '(elisp)Type Specifiers' node as this was never documented and I think
>> deserves its own space.
>>
>> I referenced it from '(emacs)Name Help' where I mentioned we report
>> function type specifiers.  Also I could reference it from '(elisp)
>> Declare Form' so that the concept of type specifier (there already
>> mentioned) is explained.
>>
>> There are some mentions of type specifiers in cl.texi which I guess I'll
>> add some xref as well.
>>
>> WDYT?
>
> Thanks, some minor comments below.
>
>> diff --git a/doc/emacs/help.texi b/doc/emacs/help.texi
>> index f15b4c5e89d..0f85ff0c832 100644
>> --- a/doc/emacs/help.texi
>> +++ b/doc/emacs/help.texi
>> @@ -322,6 +322,13 @@ Name Help
>>  yet further information is often reachable by clicking or typing
>>  @key{RET} on emphasized parts of the text.
>>
>> +The function type, if known, is expressed with a function type specifier
>> +(@pxref{Type Specifiers,,,elisp, The Emacs Lisp Reference Manual}), it
>
> It would be good to have "function type specifier" in @dfn here, and
> also have a @cindex entry for that.
>
>> -@var{type} is a type specifier in the form @w{@code{(function
>> +@var{type} is a @ref{Type Specifier} in the form @w{@code{(function
>
> "Type Specifiers", in plural.  More importantly, using @ref in such a
> way is not a good idea in Texinfo, it looks good only in the HTML
> format.  For other formats, it is better to use the wordier
>
>   @var{type} is a @dfn{type specifier} (@pxref{Type Specifiers}) in
>   the form...
>
>> +@node Type Specifiers
>> +@subsection Type Specifiers
>
> Please add an index entry here
>
>   @cindex type specifier

>> +A type specifier is an expression that denotes a type. A type represents
>                                                         ^^
> Two spaces between sentences.
>
>> +a set of possible values.  Type specifiers can be classified in
>> +primitives and composites.
>
> Since type specifiers are mostly (only?) used for functions, perhaps
> the section should explicitly talk about "function type specifiers",
> or at least mention "function" in several places in the text?

They are also usable under `cl-the', 'cl-defstruct' and probably few
other cl facilities.  (BTW I'd like to have 'cl-the' or a new 'the'
wired to the compile machinery for the future).

>> +@subsubsection Primitive type specifiers.
>> +Primitive types specifiers are the basic types (i.e. not composed by other
>
> "i.e." needs a @: after it, since the period doesn't end a sentence.
>
>> +Built-in primitive types (like @code{integer}, @code{float},
>> +@code{string} etc) are listed in @xref{Type Hierarchy}.
>
> @ref, not @xref.  The latter is only pertinent at the beginning of a
> sentence, since it produces a capitalized "See".
>
>> +@subsubsection Composite type specifiers.
>> +Composite type specifiers allow the definition of complex types by
>> +combining simpler types.
>
> Instead of having @subsections here, I'd use a @table (with the
> composite type specifiers being a nested @table inside that).
>
> A
> @table is easier to read and grasp, and also can save you typing,
> since you can say
>
>   @table @code
>
> and avoid the need to use @code for each symbol.
>
>> +@item @code{and}
>> +
>> +Similarly the @code{and} type specifier describes a type that satisfies
>> +at all the given types.
>    ^^
> That "at" should be removed.
>
>> +The @code{function} type specifier in the form @w{@code{(function
>> +(ARG-1-TYPE ... ARG-N-TYPE) RETURN-TYPE)}} used to describe the argument
>
> The symbols you have in UPPER-CASE should be actually in @var and in
> lower-case, as we always do with meta-syntactic arguments (i.e., with
> symbols that stand for something other than themselves literally).
>
>> +types and return type of a function. Argument types can be interleaved
>                                       ^^
> Two spaces.
>
>> +The @code{integer} type specifier is used to define a subset of integers
>> +by specifying a range. This allows to precisely control which integers
>                         ^^
> Likewise.
>
>> +are valid for a given type.
>> +
>> +The general form is:
>> +@example
>> +(integer lower-bound upper-bound)
>> +@end example
>> +Where @code{lower-bound} is the minimum integer value in the range and
>> +@code{upper-bound} the maximum.  It is possible to use @code{*} to
>> +indicate no lower or uper limit.
>> +
>> +The following represents all integers from -10 to 10.
>> +@example
>> +(integer -10 10)
>> +@end example
>> +
>> +The following represents 10.
>> +@example
>> +(integer 10 10)
>> +@end example
>> +
>> +The following represents all integers from negative infinity to 10.
>> +@example
>> +(integer * 10)
>> +@end example
>
> I wonder whether the description of the 'integer' type should be in
> the "primitive types" part, since 'integer' is a primitive type, and
> mentioned there?

'integer' is a primitive type when used alone, but is a compound one if
used as (integer min max).  I think I've clarified that.

> A general note: I miss some higher-level background information here,
> which would explain how these types are generated and how and for what
> purposes they are used.  Such background doesn't have to be too
> detailed or too technical, but it is important to provide the
> rationale for this feature.

Okay I tried to add some brief context.

Attached the latest version where I tried to implement the suggestions.

Thanks!

  Andrea