orangy

class Event<T> {
    private val handlers = arrayListOf<(Event<T>.(T) -> Unit)>()
    fun plusAssign(handler: Event<T>.(T) -> Unit) { handlers.add(handler) }
    fun invoke(value: T) { for (handler in handlers) handler(value) }
}
 
val e = Event<String>() // define event
 
fun main(args : Array<String>) {
    e += { println(it) } // subscribe