Dissecando coroutines 5

sealed class ActorCommand<out T> {
    class REGISTER<T>(val id: Int, val name: String, val response: SendChannel<T>? = null) : ActorCommand<T>()
    class REMOVE<T>(val id: Int, val response: SendChannel<T>? = null) : ActorCommand<T>()
    class QUERY<T>(val response: SendChannel<T>) : ActorCommand<T>()
}

val actorJob = actor<ActorCommand<Any?>> {
    val state = mutableMapOf<Int, String>()
    for (msg in channel) {
        when (msg) {
            is ActorCommand.REGISTER -> {
                val result = state.getOrPut(msg.id) {
                    msg.name
                }
                msg.response?.send(result)
            }
            is ActorCommand.REMOVE -> {
                val result = state.remove(msg.id)
                msg.response?.send(result)
            }
            is ActorCommand.QUERY -> msg.response.send(state.toMap())
        }
    }
}