language-lua

Lua parser and pretty-printer

http://github.com/glguy/language-lua

LTS Haskell 24.16:0.11.0.2
Stackage Nightly 2025-07-14:0.11.0.2
Latest on Hackage:0.11.0.2

See all snapshots language-lua appears in

BSD-3-Clause licensed by Ömer Sinan Ağacan, Eric Mertens
Maintained by Eric Mertens
This version can be pinned in stack with:language-lua-0.11.0.2@sha256:5eedabf72cad2f286061b81ae2d6d8df1e9c9ed27e8924461aabb742aa9213ba,2328

Module documentation for 0.11.0.2

language-lua - Lua 5.3 lexer, parser and pretty-printer

Build Status Hackage

This package is just like any other language x packages. It provides lexer, parser and pretty-printer for Lua programming language.

Haddock documentation

Usage

This module provides 3 parsers.

  • chunk: Lua file parser.
  • exp: Lua expression parser.
  • stat: Lua statement parser.

Lexing is needed before running a parser. parseText function runs lexer before parsing. So if you want to parse a Lua expression, you can call parseText exp string, where string is the Lua expression to parse.

parseFile is a helper to parse Lua files. Example: parseFile "/path/to/lua/file". This is same as parseText chunk `fmap` readFile path.

Note that parseText may result with failure, so it’s return type is Either ParserError a.

Lexer

Lexer is not exported by top-level Language.Lua module. You need to import Language.Lua.Lexer. After that, llex string scans the string and returns token list. Tokens are defined in Language.Lua.Token.

Pretty-printer

Pretty-printer is still under development, and subject to lots of changes. It works, but lots of functionality will be added.

For now, you can use pprint syntax_tree to pretty-print a Lua syntax tree.

Changes

Changelog

0.11.0.2

  • Update to work with newer packages

0.11.0.1

  • Update to work with newer base

0.11.0

  • Migrates custom lexer logic to alex-tools package
  • Floating-point and integers distinguished in Exp type

0.10.0

  • Track the end positions of tokens and the AST in addition to the start

0.9.0

  • Transition to parsing Text using a simplified alex lexer and happy parser

0.8.0

  • We can now parse Unicode strings from UTF-8 encoded files. By default these literals are not interpreted, and we have StringLiteral.interpretStringLiteral for interpretation and StringLiteral.constructStringLiteral for constructing Lua string literals from UTF-8 encoded ByteStrings.

    Main invariant is that if you print a parsed Lua string, it should be printed the same way. (including long strings)

  • Empty statements(EmptyStat) are now printed by pretty printer to avoid ambiguous printing. Previously these two statements were printed the same:

    f();(f)()
f()(f)()

    But the first line does not have the parse ambiguity(3 function applications in one statement or two function application statements).

  • Forgotten Annotated instance for Name implemented.

  • Some warnings are fixed for GHC < 7.10.

0.7.1

  • Integer division parsing fixed.

0.7.0

  • language-lua now supports Lua 5.3.
  • Some warnings printed with base >= 4.8 are fixed.

0.6.3.3

  • Some bugs related with assignment statement parsing are fixed(#22).
  • Wrong error message for expected == operator is fixed(#23).

0.6.3.2

  • Build fixed for GHC 7.10.

0.6.3.1

  • Build-tools field is added to Cabal file.

0.6.3

  • Fixed some issues with string parsing. (#17)
  • Added named variant of text parsers to allow specifying source names. (#18)

0.6.2.1

  • Missing test files are added to Cabal package.

0.6.2

  • base dependency is relaxed for GHC 7.10. Note that alex version

    3.1.4 is required to compile with GHC 7.10.

0.6.1

  • Generic and NFData instances are implemented for syntax trees.

0.6.0

  • Fixed a long string literal parsing bug which was causing long strings to terminate at wrong points.
  • \z escape characters in strings are now scanned and interpreted correctly.
  • This is first version that parses all of Lua 5.2.2 test suite.

0.5.0

  • 2-years-old operator parsing bug fixed. Chained/nested operator expressions are now properly parsed.

0.4.6

  • Language.Lua.Annotated.Lexer module exposed.

0.4.5

  • Fixed a bug that made lexer accept invalid escape sequences in strings.
  • Strings are now interpreted -- string “\n” is now parsed to Haskell string “\n”, instead of “\\n”.
  • Fixed character code parsing.

0.4.4

  • Printer now takes operator precedences into account while printing Binop and Unop expressions and prints parenthesis as necessary.
  • Printer now does not put line break in Binop expressions.

0.4.3

  • Data and Typeable instances are implemented for syntax tree.

0.4.2

  • More tweaks in pretty printer.
  • Started using 2 spaces for indentation(instead of 4 as before).

0.4.1

  • Some tweaks in pretty-printer.

0.4.0

  • Table and FunDef nodes are removed from simplified syntax.

0.3.1

  • Fixed incorrectly exported name exp in Language.Lua.Parser module.

0.3.0

  • Added non-annotated syntax to make code-generation easier.

0.2.3

  • Minor internal changes.

0.2.2

  • Some tweaks in pretty-printer.

0.2.0

  • Syntax tree is annotated. All parsers(parseText, parseFile) annotate resulting tree with source positions.