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Lua eXtended

Lua eXtended

luax is a Lua interpreter and REPL based on Lua 5.4, augmented with some useful packages. luax can also produce executable scripts from Lua scripts.

luax runs on several platforms with no dependency:

luax can « compile1 » scripts from and to any of these platforms.

luaxc compiles2 scripts into a single executable containing the LuaX runtime and the Lua scripts. The target platform can be explicitly specified to cross-compile scripts for a supported platform.

Getting in touch

Requirements

Compilation

luax is written in C and Lua. The build system uses Ninja and Zig (automatically downloaded by the Ninja file).

Just download luax (https://github.com/CDSoft/luax), generate build.ninja and run ninja:

$ git clone https://github.com/CDSoft/luax
$ cd luax
$ ninja -f bootstrap.ninja  # compile Lua and generate build.ninja
$ ninja             # compile LuaX
$ ninja test        # run tests
$ ninja doc         # generate LuaX documentation

Note: ninja will download a Zig compiler.

If the bootstrap stage fails, you can try:

  1. to use another C compiler:
  2. or install Lua and generate build.ninja manually:

Compilation options

Option Description
bang -- fast Optimized for speed
bang -- small Optimized for size
bang -- debug Debug symbols kept, not optimized
bang -- san Compiled with ASan and UBSan (implies clang)
bang -- zig Compile LuaX with Zig
bang -- gcc Compile LuaX with gcc
bang -- clang Compile LuaX with clang

bang must be run before ninja to change the compilation options.

lua tools/bang.lua can be used instead of bang if it is not installed.

The default compilation options are fast and zig.

Zig is downloaded by the ninja file. gcc and clang must be already installed.

Compilation in debug mode

LuaX can be compiled in debug mode (less optimization, debug symbols kept in the binaries). With the san option, the tests are executed with ASan and UBSan. They run slower but this helps finding tricky bugs.

$ git clone https://github.com/CDSoft/luax
$ cd luax
$ tools/bang.lua -- debug san # generate build.ninja in debug mode with sanitizers
$ ninja                       # compile LuaX
$ ninja test                  # run tests on the host

Cross-compilation

When compiled with Zig, ninja will compile luax and luaxc.

luaxc is a Bash script containing precompiled libraries for all supported targets. This script can bundle Lua scripts and link them with the LuaX runtime of the specified target.

E.g.: to produce an executable containing the LuaX runtime for linux-x86_64 and hello.lua:

$ luaxc -t linux-x86_64-musl -o hello hello.lua

Precompiled LuaX binaries

In case precompiled binaries are needed (GNU/Linux, MacOS, Windows), some can be found at cdelord.fr/hey. These archives contain LuaX as well as some other softwares more or less related to LuaX.

Warning: There are Linux binaries linked with musl and glibc. The musl binaries are platform independent but can not load shared libraries. The glibc binaries can load shared libraries but may depend on some specific glibc versions on the host.

Installation

$ ninja install                 # install luax to ~/.local/bin and ~/.local/lib
$ PREFIX=/usr ninja install     # install luax to /usr/bin and /usr/lib

luax is a single autonomous executable. It does not need to be installed and can be copied anywhere you want.

LuaX artifacts

ninja install installs:

Usage

luax is very similar to lua and adds more options to compile scripts:

usage: luax [options] [script [args]]

General options:
  -h                show this help
  -v                show version information
  --                stop handling options

Lua options:
  -e stat           execute string 'stat'
  -i                enter interactive mode after executing
                    'script'
  -l name           require library 'name' into global 'name'
  -l g=name         require library 'name' into global 'g'
  -l _=name         require library 'name' (no global variable)
  -                 stop handling options and execute stdin
                    (incompatible with -i)

Compilation options:
  -t target         name of the targetted platform
  -t list           list available targets
  -o file           name the executable file to create
  -q                quiet compilation (error messages only)

Scripts for compilation:
  file.lua          name of a Lua package to add to the binary.
  file.xxx          file embeded as a module
                    returning the content of the file.

Lua and Compilation options can not be mixed.

Environment variables:

  LUA_INIT_5_4, LUA_INIT
                    code executed before handling command line
                    options and scripts (not in compilation
                    mode). When LUA_INIT_5_4 is defined,
                    LUA_INIT is ignored.

  PATH              PATH shall contain the bin directory where
                    LuaX is installed

  LUA_PATH          LUA_PATH shall point to the lib directory
                    where the Lua implementation of LuaX
                    lbraries are installed

  LUA_CPATH         LUA_CPATH shall point to the lib directory
                    where LuaX shared libraries are installed

PATH, LUA_PATH and LUA_CPATH can be set in .bashrc or .zshrc
with « luax env ».
E.g.: eval $(luax env)

« luax env » can also generate shell variables from a script.
E.g.: eval $(luax env script.lua)

When compiling scripts (options -t and -o), the scripts shall contain tags (e.g. in comments) showing how the script is used by LuaX:

Scripts without tags are classified using a simplistic heuristic:

This heuristic should work for most of the Lua scripts but explicit tags are recommended.

LuaX can also embed files that are not Lua scripts. These files are embedded as Lua modules that return the file content as a string. In this case, the module name if the file name.

Note for Windows users: since Windows does not support shebangs, a script script shall be explicitly launched with luax (e.g.: luax script). If script is not found, it is searched in the installation directory of luax or in $PATH.

Examples

# Compilation (standalone executable script for LuaX)
$ luax -o executable main.lua lib1.lua lib2.lua
$ ./executable      # equivalent to luax main.lua

# Compilation for Lua
$ luax -o executable -t lua main.lua lib1.lua lib2.lua
$ ./executable      # equivalent to lua main.lua

# Compilation for Pandoc Lua
$ luax -o executable -t pandoc main.lua lib1.lua lib2.lua
$ ./executable      # equivalent to pandoc lua main.lua

# Available targets
$ luax -t list
lua
luax
pandoc

Built-in modules

The luax runtime comes with a few builtin modules.

Some modules are heavily inspired by BonaLuna and lapp.

Shared libraries

LuaX is also available as a shared library. This shared library is a Lua module that can be loaded with require. It provides the same modules than the LuaX executable and can be used by a regular Lua interpreter (e.g.: lua, pandoc, …).

E.g.:

$ lua -l libluax
Lua 5.4.6  Copyright (C) 1994-2023 Lua.org, PUC-Rio
> F = require "F"
> F.range(100):sum()
5050
> F.show({x=1, y=2})
{x=1, y=2}
> F.show({x=1, y=2}, {indent=4})
{
    x = 1,
    y = 2,
}

Pure Lua modules

LuaX modules also provide pure Lua implementations (no LuaX dependency). The script lib/luax.lua can be reused in pure Lua programs:

License

luax is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

luax is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with luax.  If not, see <https://www.gnu.org/licenses/>.

For further information about luax you can visit
http://cdelord.fr/luax

luax uses other third party softwares:


  1. luax is actually not a « compiler ».

    It just bundles Lua scripts into a single script that can be run everywhere LuaX is installed.↩︎

  2. luaxc uses zig to link the LuaX runtime with the Lua scripts but the Lua scripts are actually not compiled. Contrary to luax, luaxc produces executables that do not require LuaX to be installed.↩︎