slinky-native scala 3 support?

[evelant]

I'm just dipping my toes into Scala(js) and I'm interested in using slinky since I have an existing large react-native app and Typescript is torturous to write and maintain. It looks like there are no artifacts available for slinky-native on scala 3 however. Is this intended?

[shadaj]

Ah, this is due to the React Native bindings using the @react annotation, which isn't supported on Scala 3. You may have better luck with the ScalablyTyped bindings, there's a good chance those will become the recommended approach soon anyways.

[evbo]

This is the only Scala 3 issue I've found open and I'd like to clarify: is this the minimal example on how to compile a component with Slinky in Scala 3 and react (native)?:

package example

import example.app.App
import org.scalajs.dom
import org.scalajs.dom.document
import slinky.core.FunctionalComponent
import slinky.core.facade.{React, ReactElement}
import slinky.web.ReactDOM
import slinky.web.html.{div, h1}

import scala.scalajs.js
import scala.scalajs.js.annotation.JSImport


@main
def Example(): Unit = {
  ReactDOM.render(App.component(App.Props()), dom.document.getElementById("root"))
}

where App is:

package example.app

import slinky.core.FunctionalComponent
import slinky.web.html.h1

object App {
  case class Props()
  val component = FunctionalComponent[Props] { props =>
    h1(s"Hello, slinky!")
  } 
}

Would be great if there's a more succinct approach, like still being able to achieve @react's fancy .apply look and feel!

[shadaj]

Yep, unfortunately for now there's no way to get the nice apply implementations since there is no support for macros that introduce new APIs.

[evbo]

How should ExternalComponent be handled in Scala 3?

Update

slinky/core/src/main/scala-3/slinky/core/ExternalComponent.scala

Line 80 in b1e7e02

def apply(p: Props): BuildingComponent[E, R] =

Super simple! So instead of MyComp.component(MyComp.Props(..)) it's just calling the apply method: MyComp(MyComp.Props(..))

[shadaj]

This is a good point. For now we could just make @react a no-op on Scala 3.

Then again, I've been considering deprecating the React Native bindings entirely in favor of ScalablyTyped ones, which are more up to date and work across Scala 2/3.

[evbo]

Another big Scala3 feature yet to be supported: Reader and Writer

Currently if you try to Read or Write using case classes, the macro will fail to capture the js.Object, failing in some way like:

TypeError: null is not an object (evaluating '$thiz.forceRead__sjs_js_Object__O')

As a best effort, I still use Reader and Writer but only with js.Object, not case classes. It defeats the purpose but maintains a consistent API for when these are eventually supported for Scala 3

[evbo]

ouch! Just hit a very hard to catch incompatibility with Scala3:

the children: ReactElement* Prop does not correctly produce a Seq[ReactElement] if you pass a Seq[ReactElement] for that argument. What happens is it produces something like Seq(Fragment(children)), so a Seq but always of length 1!!

So be sure to always define children: Seq[ReactElement] for all elements to be properly passed. Both compile, but only that approach correctly preserves the list structure.