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84 lines
7.0 KiB
Markdown
Luau  [](https://codecov.io/gh/luau-lang/luau)
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====
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Luau (lowercase u, /ˈlu.aʊ/) is a fast, small, safe, gradually typed embeddable scripting language derived from [Lua](https://lua.org).
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It is designed to be backwards compatible with Lua 5.1, as well as incorporating [some features](https://luau-lang.org/compatibility) from future Lua releases, but also expands the feature set (most notably with type annotations). Luau is largely implemented from scratch, with the language runtime being a very heavily modified version of Lua 5.1 runtime, with completely rewritten interpreter and other [performance innovations](https://luau-lang.org/performance). The runtime mostly preserves Lua 5.1 API, so existing bindings should be more or less compatible with a few caveats.
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Luau is used by Roblox game developers to write game code, as well as by Roblox engineers to implement large parts of the user-facing application code as well as portions of the editor (Roblox Studio) as plugins. Roblox chose to open-source Luau to foster collaboration within the Roblox community as well as to allow other companies and communities to benefit from the ongoing language and runtime innovation. As a consequence, Luau is now also used by games like Alan Wake 2 and Warframe.
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This repository hosts source code for the language implementation and associated tooling. Documentation for the language is available at https://luau-lang.org/ and accepts contributions via [site repository](https://github.com/luau-lang/site); the language is evolved through RFCs that are located in [rfcs repository](https://github.com/luau-lang/rfcs).
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# Usage
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Luau is an embeddable language, but it also comes with two command-line tools by default, `luau` and `luau-analyze`.
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`luau` is a command-line REPL and can also run input files. Note that REPL runs in a sandboxed environment and as such doesn't have access to the underlying file system except for ability to `require` modules.
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`luau-analyze` is a command-line type checker and linter; given a set of input files, it produces errors/warnings according to the file configuration, which can be customized by using `--!` comments in the files or [`.luaurc`](https://rfcs.luau-lang.org/config-luaurc) files. For details please refer to [type checking]( https://luau-lang.org/typecheck) and [linting](https://luau-lang.org/lint) documentation.
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# Installation
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You can install and run Luau by downloading the compiled binaries from [a recent release](https://github.com/luau-lang/luau/releases); note that `luau` and `luau-analyze` binaries from the archives will need to be added to PATH or copied to a directory like `/usr/local/bin` on Linux/macOS.
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Alternatively, you can use one of the packaged distributions (note that these are not maintained by Luau development team):
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- macOS: [Install Homebrew](https://docs.brew.sh/Installation) and run `brew install luau`
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- Arch Linux: From the AUR (Arch Linux User Repository), install one of these packages via a AUR helper or manually (by cloning their repo and using ``makepkg``): [luau](https://aur.archlinux.org/packages/luau) (manual build), [luau-git](https://aur.archlinux.org/packages/luau-git) (manual build by cloning this repo), or [luau-bin](https://aur.archlinux.org/packages/luau-bin) (pre-built binaries from releases)
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- Alpine Linux: [Enable community repositories](https://wiki.alpinelinux.org/w/index.php?title=Enable_Community_Repository) and run `apk add luau`
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- Gentoo Linux: Luau is [officially packaged by Gentoo](https://packages.gentoo.org/packages/dev-lang/luau) and can be installed using `emerge dev-lang/luau`. You may have to unmask the package first before installing it (which can be done by including the `--autounmask=y` option in the `emerge` command).
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After installing, you will want to validate the installation was successful by running the test case [here](https://luau-lang.org/getting-started).
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## Building
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On all platforms, you can use CMake to run the following commands to build Luau binaries from source:
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```sh
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mkdir cmake && cd cmake
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cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo
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cmake --build . --target Luau.Repl.CLI --config RelWithDebInfo
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cmake --build . --target Luau.Analyze.CLI --config RelWithDebInfo
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```
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Alternatively, on Linux/macOS you can use `make`:
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```sh
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make config=release luau luau-analyze
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```
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To integrate Luau into your CMake application projects as a library, at the minimum you'll need to depend on `Luau.Compiler` and `Luau.VM` projects. From there you need to create a new Luau state (using Lua 5.x API such as `lua_newstate`), compile source to bytecode and load it into the VM like this:
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```cpp
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// needs lua.h and luacode.h
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size_t bytecodeSize = 0;
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char* bytecode = luau_compile(source, strlen(source), NULL, &bytecodeSize);
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int result = luau_load(L, chunkname, bytecode, bytecodeSize, 0);
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free(bytecode);
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if (result == 0)
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return 1; /* return chunk main function */
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```
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For more details about the use of host API you currently need to consult [Lua 5.x API](https://www.lua.org/manual/5.1/manual.html#3). Luau closely tracks that API but has a few deviations, such as the need to compile source separately (which is important to be able to deploy VM without a compiler), or lack of `__gc` support (use `lua_newuserdatadtor` instead).
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To gain advantage of many performance improvements it's highly recommended to use `safeenv` feature, which sandboxes individual scripts' global tables from each other as well as protects builtin libraries from monkey-patching. For this to work you need to call `luaL_sandbox` for the global state and `luaL_sandboxthread` for each new script's execution thread.
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# Testing
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Luau has an internal test suite; in CMake builds it is split into two targets, `Luau.UnitTest` (for bytecode compiler and type checker/linter tests) and `Luau.Conformance` (for VM tests). The unit tests are written in C++, whereas the conformance tests are largely written in Luau (see `tests/conformance`).
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Makefile builds combine both into a single target and can be ran via `make test`.
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# Dependencies
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Luau uses C++ as its implementation language. The runtime requires C++11, whereas the compiler and analysis components require C++17. It should build without issues using Microsoft Visual Studio 2017 or later, or gcc-7 or clang-7 or later.
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Other than the STL/CRT, Luau library components don't have external dependencies. The test suite depends on [doctest](https://github.com/onqtam/doctest) testing framework, and the REPL command-line depends on [isocline](https://github.com/daanx/isocline).
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# License
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Luau implementation is distributed under the terms of [MIT License](https://github.com/luau-lang/luau/blob/master/LICENSE.txt). It is based on Lua 5.x implementation that is MIT licensed as well.
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When Luau is integrated into external projects, we ask to honor the license agreement and include Luau attribution into the user-facing product documentation. The attribution using [Luau logo](https://github.com/luau-lang/site/blob/master/logo.svg) is also encouraged.
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