[ANN] ReScript 10.1.2 released

Hi everyone!

We are pleased to announce the latest 10.1 release, featuring our brand new async / await syntax and JSX v4 support.

To get started, install the latest rescript package with npm:

npm install rescript

Existing codebases should just work with the newest version, so feel free to upgrade right away and let us know if there’s any issues.

Check out our blog post for all the highlights and the Changelog for detailed changes.

We also released rescript/react@0.11 that works seamlessly with JSX v4 and React@18 (full changelog can be found here)

Relevant quick links:

The newest compiler is also available in our ReScript playground.

Feel free to try out the different JSX modes there as well.

Updates on the playground:

  • Starting from 10.1.2, it will automatically ship with rescript/react@0.11. Older versions will fall back to 0.10.
  • The playground will now load with a new template to allow easy JSX version manipulation
  • When sharing snippets, the playground will add the compiler version to the share url as well

This release will be a huge step towards a more convenient and productive language. We want to thank all our contributors and community members for building and testing the newest changes. Special thanks to @moondaddi for contributing the new JSX v4 transform! :clap:

Happy hacking


Hi @ryyppy

Thanks all contributors for the awesome release.

  1. There is spelling mistake in the link* rescript/react 0.11 documentation in the above post
    introductio-n → introduction
  2. According the requirements it states that rescript 10.1 require react 18. So we cannot use it rescript , rescript-react for react 17 apps. If so our production apps cannot be migrated to rescript 10.1. Any suggestions are appreciated


I think the react 18 requirement only applies to JSX V4. If you change nothing in your project configuration (so keep on using JSX V3), you should be able to keep on using react 17. @moondaddi is that correct?



@sriky27 You can keep using JSX V3 with the latest compiler and rescript-react v0.11. Please refer to the v3 compatible mode Migrate from JSX v3 | React


This isn’t entirely true. At least not without doing some adaptations if you’re using React.Context, since the new API isn’t entirely compatible with JSX v3. At the very least, context provider implementations need a makeProps function:

module Provider = {
  let makeProps = (~value, ~children, ()): React.Context.props<_> => {value, children}
  let make = React.Context.provider(context)

And in interface files, @react.component can’t be used, since the makeProps function it generates uses a JS object type, not a record type, so something like following needs to be used instead:

type context // placeholder for actual context type

module Provider: {
  let makeProps: (
    ~value: context,
    ~children: React.element,
  ) => React.Context.props<context>
  let make: React.Context.props<context> => React.element


One way to make this migration easier might be to use a functor or function returning a first-class module. Instead of writing:

module Provider = {
  let make = React.Context.provider(context)

One could write:

module Provider = React.Context.Provider({ let context = context })


module Provider = unpack(React.Context.provider(context))

Then, all that’s needed is be backwards compatible with V3 is to add a V3 namespace:

module Provider = unpack(React.Context.V3.provider(context))

which would generate a makeProps function in addition to make. And they’re both shorter than the current API to boot.

1 Like

More generally, the migration guide seems to have skipped interfaces entirely. It’s not entirely obvious what the signature for a context provider should be, for example.

One might think that this should work, since this is supposedly how you specify a props type that’s defined somewhere else:

@react.component(: React.Context.props<context>)
let make: (~value: context, ~children: React.element) => React.element

but maybe it just works for externals?

I’ve found that this works:

let make: React.Context.props<context> => React.element

but it’s a bit unfortunate that it obscures the actual props. Ideally I’d like the first example to work.

@glennsl With v3 compatible mode, you can use old react binding including React.Context API, if you open ReactV3 globally.

If you want to migrate the project from v3 to v4, then you need to rewrite some of implementations such as React.Context.
But it is not required in case you are going to keep using v3 with latest compiler and react binding.

Ah, I missed that. Thanks!

Hi @cristianoc, @moondaddi

We have successfully migrated to 10.1.2 with jsx: 3, it works with out any issues. Thanks a lot for efforts put behind this release.



Very happy to hear that!