Re: [OFFTOPIC] Re: Invoking a function from a list of functions

[Eli Zaretskii <eliz@gnu.org>]

> From: Yuri Khan <yurivkhan@gmail.com>
> Date: Thu, 29 Nov 2018 01:15:41 +0700
> Cc: help-gnu-emacs <help-gnu-emacs@gnu.org>
> 
> > That's debatable: the Unicode Standard says to act according to
> > canonical equivalence only in text, whereas the above are symbol
> > names.  We do display them the same (if the font supports that), but
> > we aren't under any obligation to map them to the same symbols, IMO.
> 
> Standard Annex 31 deals with identifiers in programming languages, and
> recommends considering identifiers equivalent if they are the same
> under Normalization Form C for case-sensitive languages (such as
> Python and Elisp).

  "Implementations that take normalization and case into account have
  two choices: to treat variants as equivalent, or to disallow
  variants."

So there's a choice.

> (It suggests using Normalization Form KC for case-insensitive
> languages, although I do not see how compatibility decomposition is
> similar to case folding.)

Case-folding is considered a special case of character folding.

> > > ELISP>  (list Α A)
> > > ("hi" "there")
> >
> > Why bad?  Those characters are not canonically equivalent.
> 
> They are not even compatibility equivalent.

I didn't say they were.

> > If you
> > want to go by compatibility equivalence, you will enter a slippery
> > slope, where, for example, Ⅰ and 1 will yield the same symbol or even
> > the same number.
> 
> No they won’t. Compatibility decomposition of U+2160 ROMAN NUMERAL ONE
> is U+0073 LATIN CAPITAL LETTER I.

Yes, a mistaken example, sorry.  But the idea is clear, I hope.  E.g.,
the compatibility decomposition of ⁵ is 5, and the compatibility
decomposition of ⑴, a single character, is (1), which is a list in
Emacs.

That way lies madness, IMO.