As previously mentioned, TeX Live 2010 will contain the first version of fontspec to support LuaTeX.

This has been made possible by a partial port of the ConTeXt OpenType font handling system by Khaled Hosny and Elie Roux in their luaotfload package (links: CTAN, Github). This package allows users to load OpenType fonts in plain LuaTeX is much the same way as in plain XeTeX:

\font\tenrm="name:Adobe Garamond Pro:+onum" at 10pt
\tenrm ...

Fonts may also be loaded by filename, as well.

\font\tenrm="file:AGaramondPro-Regular.otf:+onum" at 10pt
\tenrm ...

fontspec uses these features to provide the same interface in LuaTeX for loading fonts for LaTeX use:

\setmainfont[Numbers=OldStyle]{Adobe Garamond Pro} ...

Important comment #1: Before luaotfload can load fonts by name as in the example above, it must first create a database of installed fonts in the operating system and in the TeX distribution. This performed by executing the following script included with luaotfload

mkluatexfontdb.lua

(Use the --help option for further info.) It will take a couple of minutes the first time it is run, is quite fast to execute subsequently. This script must be run whenever a font is added or removed from your system. Work is ongoing to automate this process, but for now it still requires manual attention.

When using fontspec with XeLaTeX, it is usually recommended to load the xltxtra package, which addresses some infelicities of LaTeX (and related packages) to ensure the output using unicode fonts is as good as it should be (or even working at all).

Important comment #2: For LuaTeX, we’ve decided that there’s no point requiring a separate package to do these things, so the core of xltxtra has been simplified and included within fontspec itself. For backwards compatibility, XeTeX users should continue to use the xltxtra package, however.

Some parts of xltxtra have not been incorporated into fontspec itself. The most important feature that has not been included is automatic access to OpenType superscripts and subscripts. This feature of xltxtra has caused several headaches over the years with problems related to poor font support and conflicts with other packages that also redefine sub/superscript commands (especially related to footnotes). This feature will be released as a separate package in the near future.

A similar philosophy has been taken with Ross Moore’s xunicode package. This package defines LaTeX interfaces for a wide variety of accents, accented letters, and symbols for unicode fonts. For example, writing ’ \"u ’ to output ’ u ‘, and so on. This is the function that is usually performed transparently (for 8-bit TeX fonts) by LaTeX’s “font encoding” definitions. At the moment, xunicode is restricted to running under XeTeX only. Therefore, for LuaTeX support, we have decided (for now, at least) to incorporate the functionality of xunicode within the unicode font encoding definition used by fontspec to load its fonts (see the euenc package if you’re interested in the details).

This might be a decision we reverse or revisit later. But for now, important comment #3 is to avoid loading the xunicode package when using LuaTeX.

TeX users are long accustomed to using shorthand ligatures to type quotes and other punctuation while restricted to ASCII keyboard characters. For example, writing ’ --- ’ for an em-dash. In XeLaTeX, the standard way to achieve this same behaviour was to load the tex-text input mapping:

\setmainfont[Mapping=tex-text]{...}

Important comment #4: In LuaLaTeX, a different notation is used. Instead, you must write

\setmainfont[Ligatures=TeX]{...}

If you use the XeLaTeX syntax in LuaLaTeX, a warning will be issued but the correct behaviour will still result. The new syntax (Ligatures=TeX) is supported under XeLaTeX as well.

In summary of the above, when using LuaLaTeX simply load fontspec without any other packages:

\usepackage{fontspec}

And remember to run mkluatexfontdb.lua to keep the font database in sync.

LuaTeX support for fontspec is very new and still undergoing development. We might change the way some things currently work, and there might still be rough edges in the current behaviours. Ongoing development for LuaLaTeX is discussed on the lualatex-dev mailing list. Your feedback with suggesting improvements and reporting bugs is greatly appreciated.