[tex-hyphen] hyphenation different in xelatex?

[Élie Roux]

>>> I strongly believe that an unchanging system has great value, even 
>>> though it is axiomatic that any complex system can be improved. 
>>> Therefore I believe that it is unwise to make further
>>> “improvements” to the systems called TEX and METAFONT.

Oh, so you are probably one of the few persons on Earth using the TeX82
engine?

>>> Let us
>>> regard these systems as fixed points, which should give the same
>>> results 100 years from now that they produce today

Let me precise my point: if you use something else than TeX primitives,
your document has no guarantee whatsoever to compile with TeXLive 2115,
whatever the good will of Karl and others. And even if you use TeX
primitives, the command "tex" of TeXLive 2115 might point to TeX2115
which fixes a bug somewhere that might make your document not compile,
plus it might ship en_2115 patterns for the new English language, and it
will be the default because nobody cares anymore about the dead language
of 2015.

So yes, like with all softwares, if you compile the code of 1982 in the
environment of 1982, that should work. But that's not a very interesting
statement.

So it's all based on definitions: yes, documents written with TeX82
primitives should probably compile with the TeX82 engine, and the "tex"
command privided by TeXLive should probably be something 100% compatible
with the TeX82 engine (is it even the case? I'm not sure it may include
some evil eTeX primitives!). But is "TeX" the TeX82 engine? I don't
think so... For me (and 99% of "TeX" users, though not for people on
this list I'm sure) TeX is a kind of odd language with many different
implementations and ecosystems with which you can produce PDFs.

Thank you,
-- 
Elie