(λx.x) Ben Hanna

Software Engineer and Functional Programming Enthusiast

Building an Elm project with Parcel


  • Wed 26 September 2018
  • Blog

Do you loathe setting up the same webpack configuration for every new elm project you start? Well, worry no more because parcel, a zero-configuration bundler, now officially supports elm assets.

In this tutorial we'll setup a new project from scratch to demonstrate just how easy the process is.

Create the project

Starting from scratch let's first create a new folder and initialize npm.

mkdir my-elm-app
cd my-elm-app
npm init

Next let's install parcel. Note this is only dependency we'll explicitly have to install. Development dependencies like elm and node-elm-compiler will automatically be added to your package.json when you run parcel.

npm install --save parcel

Let's create a new folder where we'll place all our source files (HTML, CSS, JavaScript, Elm).

mkdir src

The first file we'll create is src/index.html. This will serve as our entry point for the bundler. When run, parcel will automatically resolve any dependencies contained within.

<!DOCTYPE html>
<html>
  <head>
    <script defer src="main.js"></script>
  </head>
  <body>
    <main></main>
  </body>
</html>

Next let's create a simple Elm application and save it as src/Main.elm.

import Html

main =
  Html.text "Hello World"

And lastly we'll create src/main.js which is responsible for pulling in and initializing our Elm application.

const { Elm } = require('./Main.elm');

Elm.Main.init({
  node: document.querySelector('main')
});

Serving for development

Now that all our files are in place, serving the project for development is quite easy.

npx parcel src/index.html

Then just navigate to the address presented in the terminal and you should see Hello World displayed.

The initial load will take a little longer as it will install the dependencies for elm and also initialize the elm.json file. Once it's up and running, you can make changes to any of the source files and the bundle will automatically be rebuilt.

Building for production

When you're ready to build the application for production all you do is run the following.

npx parcel build src/index.html

Upon completion, the compiled production assets can be found in the dist folder.

Wrapping up

Hopefully this article gave you a good overview on how to use parcel with elm. The complete code for this tutorial is available at my elm-parcel-example repository.