Learn how to integrate Elm 0.19.1 into your Rails 6 application using Webpacker. Follow our step-by-step guide to enhance your app with Elm’s powerful features.

Integrating Elm 0.19.1 into a Rails 6 Application with Webpacker

Introduction

Elm is a functional programming language that compiles to JavaScript and is known for its robust architecture and excellent error messages. Integrating Elm into a Rails 6 application can significantly enhance your front-end development experience. In this guide, we will walk through the steps to add Elm 0.19.1 to a Rails 6 application that uses Webpacker.

Prerequisites

Before we begin, ensure you have a Rails 6 application set up with Webpacker. You can check if Webpacker is installed by looking for the config/webpacker.yml file in your Rails root directory. If you don’t have a Rails app yet, create one by running:

rails new my_app --webpack

Next, navigate into your Rails application:

cd my_app

Installing Elm and Elm Webpack Loader

To add Elm to your Rails application, you need to install the Elm programming language and the related Webpack loader. Start by adding Elm to your project. Use the following command to install Elm globally:

npm install -g elm

Next, install the elm-webpack-loader to enable Webpack to process Elm files. Run the following command:

yarn add elm-webpack-loader

Ensure that you also have elm as a dependency in your package.json file:

yarn add elm

Configuring Webpacker for Elm

Now that Elm is installed, you need to configure Webpacker to handle Elm files. Open the config/webpack/environment.js file and add the following code to configure the loader:

const { environment } = require('@rails/webpacker')
const elm = require('elm-webpack-loader')

environment.loaders.append('elm', {
  test: /\.elm$/,
  use: [
    {
      loader: 'elm-webpack-loader',
      options: {
        // You can add options here if needed
        verbose: true,
        debug: false
      }
    }
  ]
})

module.exports = environment

Creating an Elm File

Next, create your first Elm file. In your Rails application, create a directory for your Elm files. A common practice is to create an elm directory inside app/javascript:

mkdir -p app/javascript/elm

Now, create a new Elm file called Main.elm:

touch app/javascript/elm/Main.elm

Open Main.elm in your code editor and add a simple Elm program:

module Main exposing (..)

import Browser
import Html exposing (text)

main : Program () ()
main =
    Browser.sandbox { init = (), update = \_ model -> model, view = \_ -> text "Hello, Elm!" }

Integrating Elm into Rails Views

Now that you have your Elm file ready, you need to integrate it into your Rails views. Open a view file, such as app/views/home/index.html.erb, and add the following code to render your Elm application:

javascript_pack_tag 'application'

Compiling and Running Your Application

Finally, compile your assets and run your Rails server. Use the following command to start your Rails application:

rails server

Visit http://localhost:3000 in your web browser, and you should see "Hello, Elm!" rendered from your Elm application.

Conclusion

Congratulations! You have successfully integrated Elm 0.19.1 into your Rails 6 application using Webpacker. This integration allows you to leverage the power of Elm while maintaining the structure and functionality of a Rails application. From here, you can start building more complex Elm applications, enhancing your front-end capabilities.