!elm-hot

elm-hot

This package provides the core infrastructure needed for doing hot code swapping in Elm. It supports Elm 0.19 only.

This low-level package is intended for authors of Elm application servers.

If you're looking for something that's easier to use, and you're willing to use Webpack, see elm-hot-webpack-loader, which is built using this package. Another option is Parcel which has built-in support for Elm and this package.

The goal of this package is to provide a reusable core that can be used to provide hot code swapping support in a variety of environments--not just Webpack.

Changelog

$3

- more lenient search for Browser.Navigation.Key in the generated JS
- updated dependencies

$3

- update dependencies

$3

- fixed a bug where HMR failed because Browser.Navigation.Key changed location
- fixed a crash when the app's Model contains Json.Encode.null

$3

- fixed a crash when using Elm debugger and elm/browser 1.0.2

$3

- fixed a bug where HMR would not work for very small ("toy") Elm projects

$3

- added support for Elm 0.19.1

$3

- bug fixes

$3

- improved Browser.application support (Browser.Navigation.Key can be stored anywhere in your model now)

$3

- separated the Webpack loader out into its own package
- exposed core API

$3

- first release

$3

``bash
$ npm install --save elm-hot
`

---------------------------------------------

$3


function inject(str)

Injects the hot code swapping functionality into a compiled Elm app.

- takes the Javascript code emitted by the Elm compiler as an input string
- returns a string containing the injected code ready to be eval-ed in the browser.




$3

`javascript
const elmHot = require('elm-hot');
const {compileToStringSync} = require('node-elm-compiler');
const injectedCode = elmHot.inject(compileToStringSync(["src/Main.elm"], {}));
`

In order to provide something similar to webpack-dev-server with hot module reloading, an application server could be developed to do the following:

- serve a modified version of the app developer's index.html to receive push events from the server
- watch .elm files on disk for changes
- whenever a source file changes, push an event to the client notifying it that it should fetch new code from the server
- when the client receives the event:
- fetch the new code (the server will re-compile the Elm code and use elm-hot to inject the hot-code-swapping logic)
- the client deletes the old Elm object and calls eval()` on the new code from the server

I have implemented something similar to this for the integration tests. See [test/server.js]() and [test/client.js]() for inspiration.

The above description is probably a bit too vague, so if you would like more details, create an issue.

-------------------------------------------

$3

Elm hot code swapping is based on the work of Flux Xu's elm-hot-loader.