Scalive

Live interfaces. Typed end to end.

Scalive is a Scala 3 reimplementation of the Phoenix LiveView programming model. It keeps application state, rendering, and effects on the server, handles browser interactions as typed messages, and sends efficient HTML updates through the Phoenix LiveView client.

Scalive provides Scala-first APIs for typed models, messages, routes, forms, components, and HTML, with ZIO for effects. It targets observable LiveView behavior and feature coverage rather than Phoenix source or API compatibility.

Warning

Scalive is alpha software. APIs may change without compatibility shims, and feature coverage and production maturity are still evolving. Review the project status and compatibility matrix before use.

A LiveView In Scala

import scalive.*
import zio.{Task, ZIO}

final class CounterLiveView extends LiveView[CounterLiveView.Msg, Int]:
  import CounterLiveView.Msg

  def mount(ctx: MountContext): Task[Int] =
    ZIO.succeed(0)

  def handleMessage(model: Int, ctx: MessageContext) =
    case Msg.Decrement => ZIO.succeed(model - 1)
    case Msg.Increment => ZIO.succeed(model + 1)

  def view(model: Signal[Int]): HtmlElement[Msg] =
    mainTag(
      h1("Scalive counter"),
      button(typ := "button", on.click(Msg.Decrement), "Decrease"),
      outputTag(aria.live := "polite", model.map(_.toString)),
      button(typ := "button", on.click(Msg.Increment), "Increase")
    )

object CounterLiveView:
  enum Msg:
    case Decrement, Increment

Run the counter or build it from scratch.

Start Here

• Learn the programming model
• Explore runnable examples
• Browse the API reference
• Check Phoenix LiveView compatibility

Development

Enter the repository development environment and run the common checks:

nix develop
mill __.reformat + __.fix
mill __.test
mill documentation.check

After a public API change, run mill documentation.pipeline.updateApiSnapshot to accept the new API. After a browser-visible change, run the browser suites with ./scripts/e2e-run-upstream.sh and ./scripts/e2e-run-e2e-app.sh. After a change to rendering, encoding or the runtime, run mill benchmarks.checkRegressions, which compares allocation and retained heap with a baseline; run mill benchmarks.updateRegressionBaseline to accept an intended change.

The Nix shell also provides the hash-pinned Phoenix client resources required by the Mill build. Run maintainer builds inside nix develop; published artifacts remain self-contained and impose no Nix requirement on application consumers.

Each checkout runs its own Mill daemon. Its heap is capped in the build.mill header (mill-jvm-opts), which also makes it return unused heap to the system when idle. The JVMs the build forks are capped too: tests through ScaliveTests.forkArgs, and run, runBackground, JMH benchmarks and the documentation tools through ScalaCommon.forkArgs, which the browser-test apps override.

The snapshot workflow also runs the root-slice and upstream Phoenix LiveView browser suites.

Report bugs, missing behavior, and focused feature requests through GitHub issues.

License

Scalive is available under the MIT License.