[tex-hyphen] Hyphenation of Uyghur

[Arthur Rosendahl]

On Fri, Feb 26, 2021 at 11:00:17PM +0100, Yannis Haralambous wrote:
> Arthur said he would have a different solution.

  Never mind, it doesn’t work :-)  I was toying with the idea of giving
a single character the behaviour of “join before, then display a visible
hyphen”, and I wanted to do that by making \hyphenchar active and
\def’ing to being two characters, but that doesn’t work (I just tested):
\hyphenchar really has to ultimately expand to a number, which is then
used as a glyph index in the current font.

  Nonetheless, the initial part of my idea can possibly be reused, since
there is a Unicode character with almost exactly the behaviour I
described, namely U+2010 HYPHEN (contrasting with U+2011 NON-BREAKING
HYPHEN).  So a possible solution would simply be to implement that
behaviour into TeX engines.

  The above for the pre-break line; for the post-break line I don’t
think we need to do anything because it should probably look as if it
started with the second part of the word: that’s what happens with every
other language.  If you start reading a line just after a hyphenating
break there is no typographical cue to tell you if this really is a
whole word or just part of one -- quite different from before the break.

	Arthur