Coming from Elm

The same

• The language: syntax, type system, pattern matching, records, custom types, ports.
• The error messages, written to match Elm’s.
• Html, Html.Attributes, Html.Events, Html.Keyed, Html.Lazy.
• Browser.sandbox, element, document and application, with Browser.Navigation, Browser.Events and Browser.Dom.
• The upstream TodoMVC builds and runs without changes.

What to change

The global is Dartea

const app = Elm.Main.init({ node: document.getElementById("app") });
const app = Dartea.Main.init({ node: document.getElementById("app") });

The command

elm make src/Main.elm --output=index.html
npx dartea make src/Main.elm --output index.html

dartea make takes the same shape of arguments as elm make, and the extension of --output chooses a page, a script or a folder of modules.

Build tools

vite-plugin-elm and elm-webpack-loader call the elm binary. They do not know about dartea yet. Until they do, build with dartea make and point your bundler at the output.

Projects and packages

dartea reads dartea.json. An existing elm.json is read too, for its source-directories. Dependencies come from npm through dartea install. Packages from the Elm package registry are not downloaded yet.

Caution

Packages from package.elm-lang.org are the next big piece of work. Until then a project that imports one, such as elm/svg or elm/parser, will not build.

Standard library

Package	Status
elm/core	Ready, except Debug, Bitwise, Set, Array and Process
elm/html	Ready
elm/browser	Ready
elm/json	Ready
elm/url	Ready
elm/http	Ready, without Bytes and File bodies
elm/time	Partly
elm/random	Not yet
elm/virtual-dom	Ready, through Html

Differences you might notice

• A Task is an async function and can be cancelled through its AbortSignal.
• Cmd.batch starts every command at once. Messages still arrive in order.
• The output is modern JavaScript. It does not run in browsers without ES modules and async.