server-reason-react

Native implementation of React's server-side rendering (SSR) and React Server Components (RSC) architecture for Reason.

Designed to be used with reason-react and Melange. Together it enables developers to write efficient React components using a single language, while target both native executable and JavaScript.

Features

• Server-side rendering HTML with ReactDOM.renderToString/ReactDOM.renderToStaticMarkup
• Server-side rendering streaming HTML with ReactDOM.renderToStream (similar to react@18 renderToReadableStream)
• Includes React.Suspense and React.use() implementations
• server-reason-react-ppx - A ppx transformation to support JSX on native
• All reason-react interface is either implemented or stubbed (some of the methods, like React.useState need to be stubbed because they aren't used on the server!)
• React Server Components - A ReactServerDOM module for streaming RSC payload, an esbuild plugin to enhance the bundle with client-components mappings, a Dream middleware to serve the RSC endpoint and a dummy implementation of a router (still work in progress)

Warning: This repo contains a few parts that are considered experimental and there's no guarantee of stability. Most of the stable parts are used in production at ahrefs.com, app.ahrefs.com and wordcount.com. Check each module's documentation for more details.

Why

There are plenty of motives for it, the main one is that ahrefs (the company I work for) needs it. We use OCaml for the backend and Reason (with React) for the frontend. We wanted to take advantage of the same features from React.js in the server as well.

Currently 100% of the public site (ahrefs.com), the shell part of the dashboard (app.ahrefs.com) and wordcount.com are rendered on the server with server-reason-react.

What made us create this library was mostly:

• Use the same language (Reason) for both server and client
• Embrace server-client integrations such as type-safe routing, JSON decoding/encoding, sharing types and logic, while keep enjoying functional programming patterns
• Native performance is better than JavaScript performance (Node.js, Bun, Deno)
• Writing React from a different language than JavaScript, but still using the brilliant pieces from the ecosystem
• Exploration of OCaml effects and React
• Further exploration with OCaml multicore, direct-style and concurrency with React features such as async components, React.use or Suspense

Explained more about the motivation in this blog post and also in my talk about Universal react in OCaml at fun-ocaml 2024 and Server side rendering React natively with Reason at ReactAlicante 2023

Other libraries inside this repo

Aside from the core (React, ReactDOM and ReactServerDOM), server-reason-react repo contains some common melange libraries to ensure components are universal. Some of them are reimplementations in native of those libraries, and others are new implementations. Currently they are part of the repository, but eventually will be moved out to their own opam packages and repositories.

Name	Description	Melange equivalent library
server-reason-react.browser_ppx	A ppx to discard code for each platform with different attributes: let%browser_only, switch%platform and @platform
server-reason-react.url_js and server-reason-react.url_native	Universal URL module: binds to window.URL in browser, implemented with opam-uri in native
server-reason-react.melange_ppx	A ppx to add the melange attributes to native code	melange.ppx
server-reason-react.promise	Vendored version of aantron/promise with melange support PR#80	promise
server-reason-react.belt	Implementation of Belt for native API reference	melange.belt
server-reason-react.js	Implementation of Js library for native (unsafe/incomplete)	melange.js
server-reason-react.fetch	Stub of fetch with browser_ppx to compile in native	melange.fetch
server-reason-react.webapi	Stub version of Webapi library for native code compilation	melange-webapi
server-reason-react.dom	Stub version of Dom library for native code compilation	melange-dom

Documentation

The documentation site is generated with odoc and hosted on GitHub Pages.

Demo

The demo folder contains a simple server to showcases the usages of `server-reason-react. Check the README for how to setup and run it.

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