Penlight Lua Libraries

Why a new set of libraries?

Penlight brings together a set of generally useful pure Lua modules, focusing on input data handling (such as reading configuration files), functional programming (such as map, reduce, placeholder expressions, etc), and OS path management. Much of the functionality is inspired by the Python standard libraries.

Module Overview

Paths, Files and Directories

path: queries like isdir,isfile,exists, splitting paths like dirname and basename
dir: listing files in directories (getfiles,getallfiles) and creating/removing directory paths
file: copy,move; read/write contents with read and write

Application Support

app: require_here to rebase require to work with main script path; simple argument parsing parse_args
lapp: sophisticated usage-text-driven argument parsing for applications
config: flexibly read Unix config files and Windows INI files
strict: check for undefined global variables - can use strict.module for modules
utils,compat: Penlight support for unified Lua 5.1/5.2 codebases
types: predicates like is_callable and is_integer; extended type function.

Extra String Operations

utils: can split a string with a delimiter using utils.split
stringx: extended string functions covering the Python string type
stringio: open strings for reading, and creating strings using standard Lua IO methods
lexer: lexical scanner for splitting text into tokens; special cases for Lua and C
text: indenting and dedenting text, wrapping paragraphs; optionally make % work as in Python
template: small but powerful template expansion engine
sip: Simple Input Patterns - higher-level string patterns for parsing text

Extra Table Operations

tablex: copying, comparing and mapping over
pretty: pretty-printing Lua tables, and various safe ways to load Lua as data
List: implementation of Python 'list' type - slices, concatenation and partitioning
Map, Set, OrderedMap: classes for specialized kinds of tables
data: reading tabular data into 2D arrays and efficient queries
array2d: operations on 2D arrays
permute: generate permutations

Iterators, OOP and Functional

seq: working with iterator pipelines; collecting iterators as tables
class: a simple reusable class framework
func: symbolic manipulation of expressions and lambda expressions
utils: utils.string_lambda converts short strings like '|x| x^2' into functions
comprehension: list comprehensions: C'x for x=1,4'()=={1,2,3,4}

Versioning

Penlight is strictly versioned according to Semantic Versioning.

In scope of the version:

functionality provided by Penlight modules/classes
based on stock Lua PuC-Rio or LuaJIT

Not in scope of the version:

Documentation
Error messages (textual changes)
Deprecation warnings (by default to stderr)

Deprecating functionality

Any version may deprecate functionality. So new deprecation notices may appear in major, minor, and patch releases. Final removal of functionality (assuming it is a breaking change) will only be done in a major version.

It is strongly suggested to use the deprecation warning mechanism to test usage of deprecated functionalities when upgrading. This is done by enabling the warning system (in Lua 5.4, or the Penlight compatibility function for earlier versions):

require "pl.compat"
warn "@on"

See pl.utils.raise_deprecation for more info.

License

Penlight is distributed under the MIT license.

Installation

Using LuaRocks: simply run luarocks install penlight.

Manually: copy lua/pl directory into your Lua module path. It's typically /usr/local/share/lua/5.x on a Linux system and C:\Program Files\Lua\5.x\lua for Lua for Windows.

Dependencies

The file and directory functions depend on LuaFileSystem, which is installed automatically if you are using LuaRocks. Additionally, if you want dir.copyfile to work elegantly on Windows, then you need Alien. Both libraries are present in Lua for Windows.

Building the Documentation

Requires ldoc, which is available through LuaRocks. Then it's a simple matter of running ldoc . from the repo.

Contributing

Contributions are most welcome, please check the contribution guidelines.

Running tests

Execute lua run.lua tests to run the tests. Execute lua run.lua examples to run examples.

History

For a complete history of the development of Penlight, please check the changelog.

jazzmedley/Penlight