LuaTeX has a great abilitiy compared to regular TeX: you are able to access the internal data structures of TeX. See my article about TeX without \TeX at <a href="http://wiki.luatex.org/index.php/TeX_without_TeX" rel="nofollow">http://wiki.luatex.org/index.php/TeX_without_TeX</a>.<p>With this access you can read and write (and create,...) these "nodes". This makes it possible to completely circumvent TeX's input language, which can be a pain to program with (sometimes it is very nice though). Now that easy access to data structures and the rather nice (simple) programming language of Lua makes it easy to build rather complex programs on top of TeX.<p>A shameless plug is my database Publishing software (see <a href="https://speedata.github.io/publisher/index.html" rel="nofollow">https://speedata.github.io/publisher/index.html</a>) which I believe takes this approach to an extreme: I can use TeX's algorithms like paragraph building, hyphenation, PDF writing and such (they are of excellent quality) and build my own software around it. I don't say that this is done on a weekend or so, but the posibilities are much, much, much greater than they were before LuaTeX was available.
It's interesting to see the trajectory of Lua adoption. The determining factor of the popularity of most languages was at the fate of large companies, (AT&T/C, Netscape/JavaScript, Microsoft/C++, Google/Python). On the flip side, Lua seems to slowly gain more and more popularity over the years. It's more "organic", for lack of a better term.<p>I really hope a big company doesn't pick Lua up, because I think the fact that it hasn't reached "Eternal September" yet is what makes it such a good language. It has room to breathe.<p>(The fact that it's beginner friendly, has an ANSI C89 implementation, and has the best/fastest JIT/FFI doesn't hurt either though :P)
Can anyone shine a light on what LuaTex actually is?<p>"an extended version of pdfTeX using Lua as an embedded scripting language" doesn't help me that much.<p>What's the advantage over (La)Tex?
A brief introduction to what you can do with LuaTeX:<p><a href="http://lwn.net/Articles/657157/" rel="nofollow">http://lwn.net/Articles/657157/</a>
If you think about it, TeX is just a compiler, right? It operates on trees, and translates some input to some output. I'd love to see the equivalent of LLVM for TeX: a modern, modular implementation that implements known best practices and is easy to integrate into other environments.<p>Maybe this is something like what LuaTeX is trying to do? It's hard to tell from their web page.