vite-plugin-elm

vite-plugin-elm

A plugin enables you to compile an Elm application/document/element on your Vite project. Hot module replacement works roughly in development.

import { Elm } from './MyApplication.elm'

Elm.MyApplication.init()

Setup

npm i -D vite-plugin-elm

Update vite.config.(js|ts)

import { defineConfig } from 'vite'
import elmPlugin from 'vite-plugin-elm'

export default defineConfig({
  plugins: [elmPlugin()]
})

Then you can import .elm file like:

import { Elm } from './Hello.elm'

then

// Mount "Hello" Browser.{element,document} on #root
Elm.Hello.init({
  node: document.getElementById('root'),
  flags: "Initial Message"
})

See /example dir to play with an actual Vite project. And this working website may help you to learn how to use.

Plugin Options

debug (Default: process.env.NODE_ENV !== 'production')

By giving a boolean, can control debug mode of Elm (means toggle Elm Debugger)

import { defineConfig } from 'vite'
import elmPlugin from 'vite-plugin-elm'

export default defineConfig({
  plugins: [elmPlugin({ debug: false })]
})

When it's false, disables debug mode in both development and production. Conversely, enables debug mode even in production by true. When production build gets debug mode, Elm's compile optimization doesn't happen.

optimize (Default: !debug && process.env.NODE_ENV === 'production')

By giving a boolean, can control build optimization, useful to use Debug elm functions

import { defineConfig } from 'vite'
import elmPlugin from 'vite-plugin-elm'

export default defineConfig({
  plugins: [elmPlugin({ debug: false, optimize: false })]
})

When true, optimize build and forbid usage of Debug elm functions. When specify optimize attribute, had to tell if need to debug or not. It's not why you want to make debug traces you want to see all actions.

Static Assets Handling

This plugin supports importing assets by giving a particular tag [VITE_PLUGIN_ELM_ASSET:<path to asset>] to leverage Vite's asset handling. When Elm code has a string, this plugin replaces it with an imported asset. That string should be just a string without any concatenation.

Html.img [ Html.Attributes.src "[VITE_PLUGIN_ELM_ASSET:/assets/logo.jpg]" ] []

Helper package

By using a Elm package elm-vite-plugin-helper, you can shorten such the tagging:

elm install hmsk/elm-vite-plugin-helper

import VitePluginHelper

Html.img [ Html.Attributes.src <| VitePluginHelper.asset "/assets/logo.png?inline" ] []

Combine multiple main files (Experimental from 2.7.0-beta.1)

By passing importing path via with URL-ish parameter(s), the plugin compiles multiple main files in a single compilation process. That generates a single Elm export which has multiple properties for each given main files. This way reduces bundle size comparing to a total size of importing each file separately since common modules/Elm core codes are not repeated.

// `Elm.App` and `Elm.Another`, both can work as like importing individually.
import { Elm } from './App.elm?with=./Another.elm'

Elm.App.init({
  node: document.getElementById('rootForApp'),
})
Elm.Another.init({
  node: document.getElementById('rootForAnother'),
})

For 3+ main files:

import { Elm } from './App.elm?with=./Another.elm&with=./YetAnother.elm'

Acknowledgement

• klazuka/elm-hot for a helpful referrence of the HMR implementation
• ChristophP/elm-esm for publishing IIFE -> ESM logic

License

MIT