Fast, Simple, Fully Typed JavaScript from the Future.

ReScript is a robustly typed language that compiles to efficient and human-readable JavaScript. It comes with a lightning fast compiler toolchain that scales to any codebase size.

• Fast and Simple. ReScript cares about a consistent and fast feedback loop for any codebase size. Refactor code, pull complex changes, or switch to feature branches as you please. No sluggish CI builds, stale caches, wrong type hints, or memory hungry language servers that slow you down.
• A Robust Type System. Every ReScript app is fully typed and provides reliable type information for any given value in your program. We prioritize simpler types over complex types for the sake of clarity and easy debugability. No any, no magic types, no surprise undefined.
• Seamless Integration. Use any library from JavaScript, export ReScript libraries to JavaScript, automatically generate TypeScript types. It's like you've never left the good parts of JavaScript at all.
• Tooling that just works out of the box. A builtin pretty printer, memory friendly VSCode & Vim plugins, a stable type system and compiler that doesn't require lots of extra configuration. ReScript brings all the tools you need to build reliable JavaScript, Node and ReactJS applications.
• Easy to adopt — without any lock-in. ReScript was made with gradual adoption in mind. If you ever want to go back to plain JavaScript, just remove all source files and keep its clean JavaScript output. Tell your coworkers that your project will keep functioning with or without ReScript!

ReScript is used by many companies to ship and maintain mission-critical products and is maintained by the ReScript community.

• Getting Started
• Documentation
• Upgrading
• How to Contribute
• License
• Acknowledgments

Follow the Installation Guide to set up a new ReScript project or integrate ReScript into your existing JavaScript project.

For more information on building React apps with ReScript, see the rescript-react documentation.

For React Native apps, see the rescript-react-native website.

The full documentation for the ReScript language can be found on our website.

The source for the ReScript documentation and website is hosted in a separate repo.

See the Upgrading Guide for instructions on upgrading to newer ReScript versions.

Read our Contributing Guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to ReScript.

The ReScript community has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.

You can learn more about our vision for ReScript in the Roadmap.

For discussions on ongoing development, see the Development section of the ReScript forum.

ReScript uses multiple licenses in this monorepo:

• compiler/: LGPL-3.0-or-later
• compiler/syntax/: MIT
• packages/@rescript/runtime/: MIT
• packages/@rescript/belt/: MIT
• rewatch/: MIT

See the repository license index in LICENSE and full license texts in COPYING.LESSER and LICENSE.MIT.

Native platform packages also contain third-party software. Their THIRD_PARTY_LICENSES files and the source inventory used to produce them are documented in licenses/README.md.

ReScript was originally created by Hongbo Zhang in 2015.

See CREDITS.md for further acknowledgements and project history.