Re: LaTeX export: when is it more useful to use LuaTeX instead of pdfTeX?

[Juan Manuel Macías]

Hi Uwe,

Uwe Brauer writes:

> Thanks for that list.
>
> Well I have felt in the past the same about pdftex, but I have partially
> switched to xetex precisely on the reasons you list.
>
> I have not have the time, to really try out Luatex. Did you have the
> time to compare it with XeTeX?

First of all, if you feel comfortable with xetex, my advice is to use
XeTeX. I've been using XeTeX for a long time, before fully migrating to
LuaTeX, and I think it's great. In fact, XeTeX was a great revolution in
the TeX ecosystem, for being able to use system fonts in a simple way.
LuaTeX came later.

The first TeX engine I ever used was Omega, an experimental engine
(later forked as "Aleph") that was the first TeX engine with full Unicode
support. But it still produced dvi files, not pdf. LuaTeX has evolved
from pdfTeX and has incorporated the more advanced and sophisticated
features of Omega/Aleph.

Any LaTeX document that you compile in XeTeX can be easily compiled in
LuaTeX. There may be some small incompatibilities, for example if you
include some native xetex primitives. You can do the test. The reverse
path is also possible, as long as the document does not contain Lua
code or luatex primitives.

In general, for an average user, moving from xetex to luatex does not
make any visible changes. The advanced features of LuaTeX, as I said,
are more on the developer side. Of course, if the user programs in Lua,
he/she can switch LaTeX code with lua code, use callbacks and pre/post
process lua filters, which offer enormous control over the document. But
it is not necessary. But keep in mind that you can get a lot of control
over the low-level gears of TeX by the Lua scripting, which is much
simpler and lighter than pure TeX.

The essential differences between luatex and xetex are in the last two
points on my list. The last point is important to keep in mind, as
more and more packages (some tremendously useful) are coming out that
only work in LuaTeX.

On the other hand, LuaTeX is an evolutionary step from pdfTeX (xetex
would be a separate branch), so luatex is meant to be the default or
"official" engine and replace pdfTeX, just as pdfTeX replaced TeX in its
day.

Best regards,

Juan Manuel