On 2/13/2016 10:10 PM, Reinhard Kotucha wrote:
On 2016-02-12 at 21:32:40 +0700, Igor Liferenko wrote:
> Can anybody explain why and how luatex hyphenates on ligatures? Is
> this incompatibility with TeX intentional, or is it just a bug
> which has not been fixed?
I don't think that it's deprecated to hyphenate at ligatures in
general. This heavily depends on the language and maybe other
constraints.
when luatex hyphenates it just looks at a sequence of characters ..
ligatures don't relate to that as they are a property of turning
character sequences into glyphs (and we have not only pattern driven
hyphenation points but also explicit hyphens and such + pre/post hyphen
characters to deal with)
so what happens after that is up to the font handler
A problem is that TeX doesn't know when a ligature is appropriate
or not. At least in German, ligatures are deprecated at boundaries of
composed words.
i sometimes wonder what would have happened if letterboxes had have
10000 slots and we'd have thousands of combinations in lead ... that not
having happened in turn makes me wonder if we could do without the
(somewhat traditionally small set of f* ligatures) ... what if we'd
never had a dot on the i ... so, this is why i don't worry too much
about missing a few (after all fonts are not always having all the f*
ones either)
Consider the German word Auflage. The fl-ligature is deprecated and
LaTeX users write
\usepackage[german]{babel}
....
Auf"|lage
in order to avoid the ligature. Nevertheless, Auf-lage is a good
hyphenation point despite the ligature, even if it wasn't disabled
manually.
within some constraints the discretionary mechanism can deal with it (it
gets hairy when there are several ligatures in a row
On the other hand I suppose that the Dutch ij-ligature shall never be
hyphenated. But with proper hyphenation patterns it won't happen
anyway.
worse: ij is indeed not so much a ligature as a sound thingie but in
fijn you definitely don't want a fi ligature and preferably some ij
kerning at least ... latin modern actually has a f i j contextual lookup
for nld for that reason
Hans
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