Noodles Practicing Medicine


    14.3.1 • Public • Published


    Node.js bindings for ReScript



    npm install rescript-nodejs


    yarn add rescript-nodejs

    Then add rescript-nodejs to bsconfig.json:

      "bs-dependencies": [

    Goal of this library

    Help all ReScript Node.js apps and libraries to be built faster by reducing the time spent on hand written bindings.


    • Have 100% coverage of Node.js api surface - Due to lack of testing and time for maintenance, it should only have enough surface to cover all common use cases. But it should have enough coverage that developers only rarely have to write a custom binding.
    • This library should be as low-level as possible (i.e. zero-cost) to allow for minimal context switching between offical Node.js documentation and the ReScript equilvalent. Due to the dynamic nature of the JS API, bending it to be idiomatic ReScript will lead to a ton of bikeshedding in design as well as sacrificing maintainability.


    • When available, prefer binding to the promise version of the library instead of the callback version to reduce binding surface. Js.Promise can be a bit of a pain, try the new Promise API.
    • Use subtyping only where the benefit is substantial. Subtyping is used for various APIs that implement Node Streams, such as HTTP Request and Response, FileSystem streams, Crypto streams, and etc. This provides a single set of functions to manipulate and combine streams across different modules. For example:

    Stream a file into stdout:

      ->Stream.onError(_ => Js.log("handleError"))

    Echo server:

    Http.createServer((request, response) => {
      request->Stream.onData(data => Js.log(data))


    We welcome and encourage anyone to contribute! In order to minimize confusion and avoid any wasted effort, here are some recommendations:

    • If you notice a bug or a typo feel free to create an issue or submit a PR to fix it.
    • If you want to request a feature/improvement, it's best to create an issue first and start a discussion. Don't spend a lot of valuable time and energy creating a pull request when it might not fit in with the project goals. Your PR may still be merged if it isn't based on an issue but expect to have a discussion first.
    • If you notice gaps in the documentation and want to help fill them in, feel free to go straight to PR. Or create an issue and provide a draft of the docs you want to add.
    • If you have concerns about implementation style or design decisions (e.g. type soundness, complexity, ergonomics, edge cases, etc.), please submit an issue voicing your concerns. Critique from the community is welcome. This library is only useful so long as it works for everyone!

    License and Credits

    All code is licensed as MIT. See LICENSE.

    This project was forked from reason-nodejs after it was (or appeared to be) abandoned. If the original authors would like to re-engage please email me.


    npm i rescript-nodejs

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