LadyLua

Single static executable, batteries-included, Lua 5.1 interpreter. A fat GopherLua amalgamation of modules in Go and Lua.

Table of Contents

• Changelog
• Why?
• Reference
• Standalone programs
• Modules
  • Available modules
  • Extensions
  • DSL modules
• Documentation and Testing
• Uses
  • SAMPLE: shell script converted to Lua
  • Declarative scripting
  • DSL modules
• FAQ
  • Why not base off Lua 5.2+?
• Statistics and numbers
  • Bloat tracker
  • Benchmark

Changelog

Next release: 0.11.0 Tarot Cruncher
+ string.trim fix
+ New module csv
+ Take STDIN as code

Current release: 0.10.0 Black Future
+ Aliases: list:push list:pop
+ Aliases: queue:push queue:pop queue:iterator
+ tuple module fixes and enhancements
+ Renamed tuple:elements to tuple:iterator
+ Renamed bimap module to map
+ Renamed deque module to queue
+ New module: state
+ New module: graph
+ New module: object
+ New module: ssh_config
+ New module: date
+ New functions: refmt.toml_to_json and refmt.json_to_toml
+ Removed rr module

Old releases:
0.9.0 Scared Shrapnel
+ Loading plain Lua source is now done through package.loaders
+ Faster VM startup time; From 18ms to <1ms in a test machine
+ Now a module to support ./cmd builds
+ Easier standalone programs
+ Added crypto.random
+ Added crypto.fast_random
+ Removed kapow module
+ New module: guard
+ New module: deque
+ New module: bimap
+ New module: tuple
+ New module: argparse
+ New global function for extending modules: extend
+ Moved exec.cmd and exec.run to exec extensions module
+ Moved json.array and json.object to json extensions module
+ Moved string extensions to separate extensions module
+ Added table.clone
+ Added table.read_only
+ Bug fix: list
+ gopher-lua fixes for pcall, select, # operator, and string.gsub
+ Add bitcask.open configuration argument for maximum value size

0.8.0 Freckled Serpent
+ New setting for exec.*; timeout in seconds
+ New json functions, array and object iterators
+ New function: os.sleep
+ Removed password module
+ Replaced kapow.not_allowed with kapow.unprocessable
+ Removed html module
+ Stripped 1MiB by removing password and html modules
+ New module: list

0.7.0 Negligent Clamshell
+ New module: bitcask
+ New function: logger.time()
+ New DSL module: Lopper
+ Removed inspect module
+ New function: crypto.valid_hmac
+ DSL modules no longer embedded
+ New module: refmt
+ New module: rr
+ Rename module uid to ksuid
+ New module: uuid
+ New module: ulid
+ New function string.split
+ New function string.splitv
+ New function string.trim_end
+ New function string.trim_start
+ New function string.contains
+ table.find is now recursive
+ New function os.outbound_ip
+ New function password.strength

0.6.0 Gummy Mastiff
+ New module: telegram
+ New module: pushover
+ New module: slack
+ New module: logger
+ New module: fsnotify
+ redis: converted to object:method style
+ buildah: New NOTIFY settings

0.5.3 Epidural Dollop
+ buildah: Consolidate APK command

0.5.2 Yelling Petunia
+ buildah: Removed default cmd config in ENTRYPOINT()
+ buildah: Removed default arguments from MKDIR(), COPY(), ADD()

0.5.1 Failed Siesta
+ Fix buildah PUSH()

0.5.0 Surplus Siesta
+ New DSL module "buildah"
+ New module "lz4"
+ Selene configuration
+ Removed redundant string.line_to_list()
+ Added string.to_map()
+ Add fourth return value for exec.command

Why?

Lua is a good language but no one wants to use it for general-purpose scripting. Complaints are 1-based indexing and missing libraries. The latter is a valid concern. The 5.2+ split also does not help. I was convinced that GopherLua would be a good base for a kitchen-sink interpreter. Writing wrappers for the vast selection of Go packages would be a breeze.

Reference

Since GopherLua is an implementation of Lua 5.1, you can use the official Lua 5.1 reference manual: Lua 5.1 Manual. Other resources are also useful just make sure they do not target 5.2+ versions. Search for PDFs of Lua 5.1 cheatsheets. The Learn in in 15 minutes series also has an entry for Lua.

Standalone programs

See this → patch_tuesday Github repository for an example of a LadyLua standalone program.

Modules

Check the docs directory for more information about these modules.

Available modules

Module	Global	Type	Source	License
argparse	N	Lua	argparse	MIT
bimap	N	Lua	cw-lua	MIT
bitcask	N	Go		MIT
crypto	N	Go	gluacrypto	MIT
csv	N	Lua	ftcsv	MIT
date	N	Lua	date	MIT
deque	N	Lua	cw-lua	MIT
exec	Y	Go		MIT
fmt	N	Lua		MIT
fs	Y	Go	gopher-lfs	Unlicense
fsnotify	N	Go		MIT
graph	N	Lua	tsort	BSD2
guard	N	Lua	guard	MIT
http	N	Go	gluahttp	MIT
json	N	Go	gopher-json	Unlicense
ksuid	N	Go		MIT
list	N	Lua	linked_list.lua	MIT
logger	N	Go		MIT
lz4	N	Go		BSD3
mysql	N	Go	gluasql	MIT
object	N	Lua	object	Unlicense
pushover	N	Go		MIT
redis	N	Go		MIT
refmt	N	Go		MIT
rr	N	Go		MIT
slack	N	Go		MIT
ssh_config	N	Go	ssh_config	MIT
state	N	Lua	ahsm	MIT
telegram	N	Go		MIT
template	N	Lua	etlua	MIT
test	N	Lua	u-test	MIT
tuple	N	Lua	tuple.lua	MIT
ulid	N	Go		APL2
uuid	N	Go		MPL2

ℹ️	If it says N in the Global field, you need to require() it. Modules that are type Go should be loaded through ll.PreloadGo

Extensions

These extensions extends a global namespace or module.

Load by adding a call to extend. Example:

extend("json")

Extension
table
string
exec
json

DSL modules

Lua modules are single file Lua source that are loaded from the current working directory.

Module
buildah
lopper

Documentation and Testing

Tests are in the tests directory. We are using u-test. Within the test code is the documentation in AsciiDoc. Generated docs are in the docs directory. Check the scripts/docs directory for the command line to generate the docs.

Uses

Besides general purpose scripting, a more specific use for me right now is using Lua for writing web apps. You can write it dynamic style like PHP but instead you have Lua. Another idea is hooking Go packages that interface with DevOps things. Instead of YAML you can program DevOps tools in Lua.

SAMPLE: shell script converted to Lua

Check this diff to get a feel of the conversion from a shell script to Lua.

Declarative scripting

Using metatables you can hide the plumbing and present a declarative interface. The following snippet can be found under the scripts directory. It is used to run the MariaDB container under systemd for testing the in-tree mysql module.

require('podman'){
  NAME = 'mariadb';
  URL  = 'docker://docker.io/library/mariadb';
  TAG  = '10.5';
  CPUS = '1';
  UNIT = require 'systemd.mariadb';
  DIR  = '/srv/podman/mariadb';
  always_update      = false;
  overwrite_password = false;
}

DSL modules

Instead of HCL or Dockerfile instructions you can possibly abstract subsystems with Lua. See the buildah module for an example of a DSL module.

FAQ

Why not base off Lua 5.2+?

Sticking with 5.1 gets you a finished language. For general purpose scripting, the 5.2+ feature are not really useful. You also have access to a significant collection of plain Lua modules. Excellent tools from the Roblox side like Selene and Stylua still works with 5.1.

Statistics and numbers

Tests	188/188
Static executable bytes	9007104

Bloat tracker

Modules that adds significant bloat to the interpreter. If you don’t need these maybe you can trim them from your fork. Just estimates though. The later added modules may have dependencies shared with earlier modules.

http	3-4MiB
redis	800KiB
mysql	500KiB
slack	230KiB
refmt	300KiB

Benchmark

Wonder how it compares to PUC-Rio Lua 5.1.5 and LuaJIT2?

Here’s a benchmark for object access time. Check the bench/ directory for the code. The results are from the default 100M runs. GopherLua is fast enough for unconvoluted work. It also demonstrates that LuaJIT is too smart for these benchmarks.

Table 1. LadyLua

68.998712974	Standard (solid)
81.63775507999999	Standard (metatable)
73.37786640899998	Object using closures (PiL 16.4)
48.266743347000016	Object using closures (noself)
46.76494954999998	Direct Access
26.742789899	Local Variable

Table 2. Lua 5.1.5

12.906285	Standard (solid)
13.649843	Standard (metatable)
13.294447	Object using closures (PiL 16.4)
9.024326	Object using closures (noself)
5.618169	Direct Access
1.76135	Local Variable

Table 3. LuaJIT 2.1

0.200721	Standard (solid)
0.200649	Standard (metatable)
0.200672	Object using closures (PiL 16.4)
0.200635	Object using closures (noself)
0.200627	Direct Access
0.200628	Local Variable

Before you go disabling function inlining to reduce the executable size; here are the benchmarks for it.

Table 4. GopherLua (disabled function inlining)

97.82842299	Standard (solid)
117.51864293899999	Standard (metatable)
103.283447037	Object using closures (PiL 16.4)
66.51865570900003	Object using closures (noself)
69.64288394199997	Direct Access
37.33177725300004	Local Variable