class MainPresenter(private val mainInteractor: MainInteractor) {

    private val compositeDisposable = CompositeDisposable()

    fun bind(mainView: MainView) {

        ...

        compositeDisposable.add(
                mergedIntentsObservable.scan(MainViewState(), this::reduce).subscribe { mainView.render(it) }
        )
    }

    fun unbind() {
        compositeDisposable.clear()
    }