reasonml/reason ? reverse-engineered prompt

Build me the Reason language project so I can compile and work with Reason code locally.

I want a repo that sets up the Reason toolchain, builds cleanly, and includes the usual developer workflow for installing dependencies, running the formatter, and running the test suite. It should feel like a real open source language project, with clear docs for contributors, a working command line experience, and support for the JavaScript and OCaml ecosystems as described in the README.

Please make sure the project is usable from a fresh clone, and that I can follow simple steps to get it running, test it, and make changes without guessing. If any current docs or setup details are needed, look them up online and use the latest recommended approach.