OCaml
⚡️ Native, high-performance, cross-platform desktop apps - built with Reason!

Revery

Build native, high-performance, cross-platform desktop apps with reason!

🚧 NOTE: Revery is a work-in-progress and in active development! 🚧

Building & Installing

Install esy

esy is like npm for native code. If you don't have it already, install it by running:

npm install -g esy

Building

• esy install
• esy build

For macOS users

If your build takes too much time then you can pre-install some libraries:

• brew install cmake
• brew install libpng ragel

For Linux users

Install the following packages with your package manager of choice:

• cmake
• ragel

For Ubuntu you may need these additional packages

• libpng-dev
• libbz2-dev
• m4

For Windows native

No additional dependencies needed.

NOTE: esy requires building from an Administrator prompt (either cmd.exe or Powershell).

For Windows Subsystem for Linux (WSL)

• sudo apt install libpng-dev libbz2-dev m4 xorg-dev libglu1-mesa-dev

NOTE: Hardware acceleration is not enabled by default in WSL (instead, WSL will fall-back to a software renderer). This is problematic for performance - for that reason, we recommend building and running Revery natively on Windows instead of with WSL. For more info see: (https://github.com/Microsoft/WSL/issues/637 and a potential workaround)

Running

After building, you can run the example app by running:

• esy x Examples

Check out our examples to see how they work!

Tests

Tests can be run with:

• esy b dune runtest

Motivation

Today, Electron is one of the most popular tools for building desktop apps - using an HTML, JS, CSS stack. However, it has a heavy footprint in terms of both RAM and CPU - essentially packing an entire browser into the app. Even with that tradeoff, it has a lot of great aspects - it's the quickest way to build a cross-platform app & it provides a great development experience - as can be testified by its usage in popular apps like VSCode, Discord, and Slack.

Revery is kind of like super-fast, native Electron - with a bundled React, Redux, and a fast build system - all ready to go!

Revery is built with reasonml, which is a javascript-like syntax on top of OCaml This means that the language is accessible to JS developers.

Your apps are compiled to native code with the Reason / OCaml toolchain - with instant startup and performance comparable to native C code. Revery also features GPU-accelerated rendering. The compiler itself is fast, too!

Revery is an experiment - can we provide a great developer experience and help teams be productive, without making sacrifices on performance?

Design Decisions

• Consistent cross-platform behavior

A major value prop of Electron is that you can build for all platforms at once. You have great confidence as a developer that your app will look and work the same across different platforms. Revery is the same - aside from platform-specific behavior, if your app looks or behaves differently on another platform, that's a bug! As a consequence, Revery is like flutter in that it does not use native widgets. This means more work for us, but also that we have more predictable functionality cross-platform!

NOTE: If you're looking for something that does leverage native widgets, check out briskml. Another alternative is the cuite OCaml binding for Qt.

• High performance

Performance should be at the forefront, and not a compromise - we need to develop and build benchmarks that help ensure top-notch performance and start-up time.

• Type-safe, functional code

We might have some dirty mutable objects for performance - but our high-level API should be purely functional. You should be able to follow the React model of modelling your UI as a pure function of application state -> UI.

Quickstart

Check out revery-quick-start to get up and running with your own Revery app!

API Example

Here's a super simple Revery app, demonstrating the basic API surface:

/**
 * The 'main' function for our app.
 */
let init = app => {
  /* Create a window! */
  let win = App.createWindow(app, "test");

  /* Set up some styles */
  let textHeaderStyle =
    Style.make(
      ~backgroundColor=Colors.black,
      ~color=Colors.white,
      ~fontFamily="Roboto-Regular.ttf",
      ~fontSize=24,
      (),
    );

  /* Set up render function */
  let render = () => {
    <view
      style={Style.make(
        ~position=LayoutTypes.Absolute,
        ~bottom=10,
        ~top=10,
        ~left=10,
        ~right=10,
        ~backgroundColor=Colors.blue,
        (),
      )}>
      <view
        style={Style.make(
          ~position=LayoutTypes.Absolute,
          ~bottom=0,
          ~width=10,
          ~height=10,
          ~backgroundColor=Colors.red,
          (),
        )}
      />
      <image src="logo.png" style={Style.make(~width=128, ~height=64, ())} />
      <text style=textHeaderStyle> "Hello World!" </text>
      <view
        style={Style.make(
          ~width=25,
          ~height=25,
          ~backgroundColor=Colors.green,
          (),
        )}
      />
    </view>;
  };

  /* Start the UI */
  UI.start(win, render);
};

/* Let's get this party started! */
App.start(init);

Custom Components

TODO

Roadmap

It's early days for revery and we still have a lot of work ahead!

Some tentative work we need to do, in no particular order:

• UI Infrastructure
  • Styles
  • State management / Redux-like layer
  • Focus Management
  • Input handling
  • Animations
  • Gestures
  • Transforms
  • Compositing / Container
  • zIndex / layers
• UI Components
  • View
  • Image
  • Text
  • Input
  • Button
  • Slider
  • Checkbox
  • ScrollView
• Platform support
  • Windows
  • OSX
  • Linux
  • Web (JS + Wasm)
• Mobile support
  • Compilation to iOS
  • Compilation to Android
• Developer Experience
  • Hot reloading
  • 'Time travel' debugging across states
  • Integrated debugger
  • Integrated performance profiler
• Audio Support
  • Wav file playback
  • MP3 file playback
• Example apps
  • Quickstart / Hello World
  • Calculator
  • Todo List

License

Revery is provided under the MIT License.

Contributing

We'd love your help, and welcome PRs and contributions. Join us on Discord!

Some ideas for getting started:

• Help us build example apps,
• Help us implement missing features,
• Help us log bugs and open issues.

Special Thanks

revery would not be possible without a bunch of cool tech:

• ocaml made these tools possible - thanks Inria & OCaml Labs!
• reasonml made revery possible - thanks @jordwalke!
• flex by @jordwalke
• briskml
  • brisk-reconciler - the "native React" implementation.
• reason-glfw
  • GLFW
  • stb-image
• reason-fontkit
  • freetype2
  • harfbuzz
• reason-gl-matrix
  • gl-matrix
  • glm

revery was inspired by some awesome projects:

• react-native
• ReactMini
• cuite
• wall
• elm