this works:

sealed class Event {
  object TYPE_ONE : Event()
  object TYPE_TWO : Event()
}

fun on(enum: Event.TYPE_ONE, block: (Int) -> Any) {

}

fun on(enum: Event.TYPE_TWO, block: (String) -> Any) {

}

on(Event.TYPE_ONE) {
  it.inc()
}

on(Event.TYPE_TWO) {
  it.length
}

but if the enum needs to be an enum, then I don’t think you can do what you’re asking for here

sealed classes seem like the way to go

It just seems unusual to use enums/sealed classes like this, at least from my experience anyhow

events should include relevant information