Node Elm Loader
A simple way to interoperate between Elm and NodeJS. Useful for sharing code between display and model logic, which holding it together with the rich Node ecosystem, for example, building your client-side components and minifying them with the rest of your assets!
Installation
You will need to already have the Elm platform installed on your system. Please find the relevant instructions here and a NodeJS development environment for v0.10.x.
Then, simply add elm-loader
as a dependency in your package.json
or run npm -g elm-loader
.
Usage
First, write a simple module in Elm and expose a port! Due to a current
bug in the compiler, you need to supply a
dummy main
function. Once this is resolved, it will be possible to proceed without the boilerplate.
module TickingPort whereimport Signalimport Signal ((<~), Signal)import Timeimport Textimport Graphics.Element (Element)main : Elementmain = Text.asText "main"port messageOut : Signal Stringport messageOut = Signal.map toString (Time.every Time.second)
Next, wire import your module into Node!
var path = require("path");var Elm = require("elm-loader");var compiledCode = Elm(path.resolve(__dirname, "ticking_port.elm"), __dirname);compiledCode.emitter.on("messageOut", function(message) {console.log(message)});
Watch it tick!
$ node test.js
1418683956865
1418683957870
1418683958873
1418683959874
1418683960875
^C
You can also access the ports
property, rather than the emitter
on the object
returned by the top level factory function and subscribe as you would with a
typical setup.
Caveats
The loader supports conventional CamelCase filenames for the Elm modules they contain.
If you prefer to split thw words in your filenames with underscores, they will automatically
be inflected to infer the module they contain, e.g. ticking_port.elm
will correspond to the
TickingPort
module above.
If you are defining ports into Elm, you also need to supply a second argument to the factory function to define the defaults for those functions, e.g.
var echoPort = Elm(path.resolve(__dirname, "fixtures/echo_port.elm"), "fixtures", { messageIn: ""});
Example
To try it out, clone this repository, run npm link
and then run node example/test.js
!