scala3-is-awesome.scala

// comparing to kotlin version: https://proandroiddev.com/extension-classes-f9dcf5878b71

sealed trait Feature
object SomeFeature extends Feature

trait AppFeatures {
  def isEnabled(feature: Feature): Boolean
}

extension (appFeatures: AppFeatures) 
  inline def apply(op: AppFeatures ?=> Unit): Unit = op(using appFeatures)

object FakeFeatures extends AppFeatures {
  def isEnabled(feature: Feature): Boolean = true
}

extension (feature: Feature)(using appFeatures: AppFeatures) 
  inline def enabled: Boolean = appFeatures.isEnabled(feature)
  inline def disabled: Boolean = !appFeatures.isEnabled(feature)

@main def main() = FakeFeatures {

  if (SomeFeature.enabled) {
    println("Some feature is enabled")
  }
}