lua-fmt is pretty-printer for Lua code, written in TypeScript and deeply inspired by prettier. lua-fmt provides an interface to format Lua code that conforms to a single and consistent standard.

While not implemented yet, the interface will be customizable to tailor the output to the user's preferences: linebreaks, string style, etc.

• npm install lua-fmt

import {formatText} from 'lua-fmt';
console.log(formatText('local hello = "Hello"; print(hello .. " world!")'))

Format a single file:

• luafmt test/lua-5.3.4-tests/calls.lua

Format a stream from stdin:

• cat test/lua-5.3.4-tests/calls.lua | luafmt --stdin

• Add support for a .luafmt preferences file

lua-fmt uses jest for automated testing.

Among the user-created tests in the test/ folder, a copy of the lua-5.3.4 tests are executed after formatting to ensure the code remains syntactically correct after formatting. For this reason, please do not modify the lua-5.3.4-tests folder unless updating with new tests from the official Lua tests. To run these tests, lua53 is expected to be available on the PATH.

When contributing changes, please consider writing tests to ensure they do not regress.

This project is licensed under the MIT License - see the LICENSE file for details.

• Oskar Schöldström - luaparse: A Lua parser written in JavaScript
• Christopher Chedeau - prettier: Prettier is an opinionated JavaScript formatter.
• Ben Newman - recast: JavaScript syntax tree transformer, nondestructive pretty-printer, and automatic source map generator.