Using LuaTeX as a replacement for pdfTeX

Question

In this question Differences between LuaTeX, ConTeXt and XeTeX various differences between LuaTeX and XeTeX (and ConTeXt) are discussed. And in this question Using XeLaTeX instead of pdfLaTeX a recipe for switching from pdfLaTeX to XeLaTeX is given. In this question, I would like a similar recipe for using LuaLaTeX. I'm particularly interested in the degree to which LuaTeX can be used as a drop-in replacement for pdfTeX. I'm not interested in things that LuaTeX can do that pdfTeX can't.

So the question is:

What do I need to do to use LuaLaTeX instead of pdfLaTeX to compile existing or new documents?

Some specific sub-questions:

1. What packages are compatible with pdfLaTeX but not with LuaLaTeX?
2. Are there any packages specific to LuaLaTeX that should be loaded in most LuaLateX documents?

Answer 1

I think we don't need to do much. The only incompatible thing I know is the UTF-8 encoding.

To answer the sub-questions:

1. Any package related to input encodings and font encodings:

   • inputenc. You should always use UTF-8 encoding to input the text. For backward compatibility, use luainputenc instead.
   • fontenc. Don't use it with fontspec explictly.
   • textcomp. Use xunicode instead, which is loaded by fontspec.
   • Most old font packages (esp. for text fonts) are better not to be used. For example, use XITS, TeX Gyre Termes or Linux Libertine O fonts with fontspec instead of times package, and use Unicode fonts for main text together with mathptmx and txfonts (font math fonts only) to get proper text fonts.
   • CJK is not compatible with LuaTeX. Today only a few unofficial LaTeX packages in Korea and Japan are available. This may be not very important for western users.

2. fontspec. To load TrueType/OpenType fonts. This is the only necessary one, I think. Also, luacode and unicode-math are useful.

Answer 2

One thing you need to consider is:

If you are using (either directly or indirectly) pdftex primitives like e.g. \pdffilemoddate (see the pdftex manual) with LuaLaTeX then you need to load Heiko Oberdiek's pdftexcmds package which adds all these commands currently missing in LuaTeX. However, these are provided as macros not as primitives and therefore do not react 100% the same way. For example \pdffilemoddate requires one expansion step more. I programmed my filemod package accordantly to load it automatically for LuaLaTeX, but other packages might not check these commands so strictly.

I don't think this is an huge issue for most documents, but definitively worth mentioning.

Answer 3

From the front lines:

I switched to LuaLaTeX in mid 2013 because I wanted TTF fonts. I am strictly using *TeX through a Makefile that has been evolving for 20 years (actually 22, if memory serves correctly).

To make the switch I ultimately converted all my framework's files to UTF8 and switched to using UTF8 only. First of course I changed the Makefile to use lualatex instead of pdftex.

To make it work I had to add:

\RequirePackage{ifluatex}
\ifluatex
   \PassOptionsToPackage{usenames,dvipsnames}{color}
   \RequirePackage{fontspec} % will load color
   \RequirePackage[latin1]{luainputenc}
\else
   \RequirePackage[latin1]{inputenc}
   \RequirePackage{times}
\fi

and then of course the font thingy:

\ifluatex
   \setmainfont[%
           UprightFont = *-regular,
           BoldFont    = *-bold,
           ItalicFont  = *-italic,
           BoldItalicFont  = LMRoman10-Bolditalic,
           SmallCapsFont = lmromancaps10-regular,
           SmallCapsFeatures = {Scale=MatchUppercase},
           SlantedFont = LMRomanslant12-Regular,
           BoldSlantedFont = LMRomanslant10-Bold,
           Renderer=Basic
      ]{lmroman12}
   \fontspec[FakeBold=4]{Latin Modern Roman Caps}
   \setsansfont[Scale=MatchUppercase,
           UprightFont = {* Regular},
           BoldFont    = {* Bold},
           ItalicFont  = {* Regular Italic},
           BoldItalicFont = {* Bold Italic}
      ]{Nimbus Sans L}
   \setmonofont[Scale=MatchLowercase]{Source Code Pro Light}
\else
\usepackage[scaled=.9]{helvet}
\fi

That's it. My framework has been working ever since. There is only one thing I haven't fixed yet (too minor): With lualatex I always get a little space in the result when I do --.

So for me it has been serving as a drop in replacement for 3 years already. Yes it can always squeak a little when UTF8 vs latin1 happens, but apart from that it just works.

A compile run with lualatex takes considerably longer than pdftex. Therefore I often used to use pdftex while writing and switch to lualatex when appearance becomes more important. However, my new Laptop has an SSD. Haven't used pdftex since ...

---

Edit 2016-06-07

I found some other caveat(s) I apparently came across while using LaTeX beamer.

\iflualatex
    \RequirePackage{newunicodechar}
    \newcommand{\DeclareUnicodeCharacter[2]{%
        \begingroup\lccode`|=\string"#1\relax
        \lowercase{\endgroup\newunicodechar{|}}{#2}%
    }
    \LoadClass[color={usenames,dvipsnames},17pt,xcolor=table]{beamer}
\else
    \LoadClass[utf8,color={usenames,dvipsnames},17pt,xcolor=table]{beamer}
\fi
\RequirePackage{eurosym}
\DeclareUnicodeCharacter{20AC}{\euro}

So when using LaTeX beamer the utf8 issue is solved differently and apparently pdftex knows \DelcareUnicodeCharacter while lualatex does not. Chances are I got the solution from this site ...

Answer 4

AFAIK, the recipe is the same as for "Using XeLaTeX instead of pdfLaTeX". Generally, what works in XeLaTeX should work in luaLaTeX also. Some packages are not fully compatible between them, some new packages for XeLaTeX are still missing from luaLaTeX, but they stay as close as possible (with exception of access to lua of course).