styled-ppx

styled-ppx is the ppx that enables css-in-reason. Build on top of emotion, it allows you to style apps safe, quickly, performant and as you always done it.

Allows you to create React Components with type-safe CSS style definitions that don't rely on a specific DSL and great error messages:

BETA: This ppx is in an early stage ⚠️. Meaning that it doesn't support full functionality as emotion or styled-components. But you can safely use it, as it would respect Compatible Versioning. In case you want to know more, take a look at the ROADMAP, or feel free to chat on Discord: @davesnx#5641

Usage

styled-ppx implements a ppx that transforms [%styled] extensions points into [@react.component] modules with the additional styles converted to emotion.

This is how you can write components in ReasonML/OCaml/ReScript with this ppx:

Standard styled component

module StyledComponent = [%styled.div
  {|
  align-items: center;
  display: flex;
  height: 100vh;
  justify-content: center;
  width: 100vw;
|}
];

<StyledComponent> {React.string("- Middle -")} </StyledComponent>,

Dynamic styled component

module Dynamic = [%styled (~color, ~background) => {j|
  color: $color;
  background-color: $background;
|j}
];

<Dynamic color="#EB5757" background="#516CF0">
  {React.string("Hello!")}
</Dynamic>

Dynamic components are somehow not fully supported, and it's the reason why the project is still in BETA.

Inline css function

<span className=[%css "font-size: 32px"]> {React.string("Hello!")} </span>

For further detail, take a look in here.

Motivation

I love CSS and coming from the JavaScript world, writing React with styled-components. I found to be one of the best combos for writting scalable frontend UIs. When I arrived to Reason, it wasn't a thing, many people have been asking for it (a few times).

So I took the time to create it with help from @jchavarri 🙌.

If you want to know more about how it works or what are the benefits I recommend to watch my talk at ReasonSTHLM Meetup

Installation

The installation process refers to the stable NPM published version (v0.20) which differs from master (v1.x). In master we won't rely on bs-emotion, so this installation will be different.

This package depends on bs-emotion, ReasonReact and BuckleScript, make sure you follow their installations.

With esy on native projects

esy add davesnx/styled-ppx

With npm or yarn on BuckleScript projects

yarn add @davesnx/styled-ppx @ahrefs/bs-emotion
# Or
npm install @davesnx/styled-ppx @ahrefs/bs-emotion

Add the PPX in your bsconfig.json file:

{
  "bs-dependencies": [
    "reason-react",
    "@ahrefs/bs-emotion"
  ],
  "ppx-flags": ["@davesnx/styled-ppx/styled-ppx"]
}

Add the PPX in your bsconfig.json file under "ppx-flags"

{
  "ppx-flags": ["esy x styled-ppx.exe"]
}

If you want to try it out, just fork https://github.com/davesnx/try-styled-ppx and follow the instalation process there.

Editor Support

One of the fears of using a ppx is editor support, we belive that having compiling errors and syntax highlight would be an amazing experience. Install the VSCode extension:

VSCode Extension

• If you are interested on another editor, please fill an issue and we would consider.

Acknowledgement

Thanks to Javier Chávarri, for helping me understand all the world of OCaml and his knowledge about ppx's. It has been a great experience. Inspired by @astrada bs-css-ppx and his implementation of CSS Parser in OCaml.

Contributing

We would love your help improving styled-ppx, there's still a lot to do. The roadmap lives under the Projects in GitHub. Feel free to take a look, ask me for advise or pick any task that you want. I tried to keep "Tasks" well organized and hopefully clear.

You would need esy, you can install the latest version from npm:

yarn global add [email protected]
# Or
npm install -g [email protected]

Then run the esy command from this project root to install and build depenencies.

esy

Editor setup

Now you can run your editor within the environment (which also includes merlin) if you use vim like so: esy $EDITOR.

esy vim

If you use VSCode, make sure you have installed OCaml Platform, and just open the editor on the root of the project.

Workflow

After you make some changes to source code, you can re-run project's build again with the same simple esy build command and run the native tests with esy test.

If you want a faster feedback look, use esy watch where runs the build automatically every file changes.

This project uses Dune as a build system, if you add a dependency in the package.json, don't forget to add it to dune as well.

Running Tests

You can test any changes from the ppx generation with different test suites. Such as:

• Native tests running esy test_native
• Snapshot tests running esy test_snapshot
• BuckleScript tests (see below). This tests are more like an end to end tests, where we run the typechecker aganinst bs-css-emotion.

also there's tests related with internal libraries such as CSS Parser, CSS Lexer and CSS Spec Parser, and all of those run with a single command: esy test.

If you want to run Bucklescript's integration test instead, you can do:

esy
cd packages/ppx/test/bucklescript
yarn install
yarn build
yarn test

Happy reasoning!