charlag

private sealed class Event {
    data class TodoCheckedEvent(val id: Long, val completed: Boolean) : Event()
    data class NewTodoEvent(val text: String) : Event()
    data class DbUpdateEvent(val todos: List<TodoEntity>) : Event()
}

charlag

inline fun <A, C, reified T> Observable<Triple<A, A, C>>.ofEventType(): Observable<Triple<A, A, T>>

charlag

@Entity(tableName = "todo")
data class TodoEntity(
        @PrimaryKey(autoGenerate = true) var id: Long,
        var text: String,
        var completed: Boolean
)
private data class State(
        val todos: List<TodoEntity>
)

charlag

fun <S, E> createConnectableKnot(
    initial: S,
    eventsSource: Observable<E>,
    reducer: (S, E) -> S,
    transformer: ObservableTransformer<in Triple<S, S, E>, out E>
): ConnectableObservable<E> {
  return Observable.create<E> { observer ->
    val state = behaviorSubjectDefault(initial)
    val events = publishSubject<E>()

charlag

fun <S, E> createKnot(
    initial: S,
    eventsSource: Observable<E>,
    reducer: (S, E) -> S,
    transformer: ObservableTransformer<in Triple<S, S, E>, out E>
): Observable<E> {
  val state = behaviorSubjectDefault(initial)
  val events = publishSubject<E>()
  eventsSource.subscribe(events::onNext)
  events.withLatestFrom(state, BiFunction<E, S, Triple<S, S, E>> { ev, oldState ->

charlag

val transformer = store.publish { upstream →
	Observable.merge(
		upstream.ofEventType<NameChangeEvent>.switchMap { (_, state, _) →
			api.validate(state.name)
		}
			.map { apiResult → ValidationResult(…) },
		upstream.ofEventType<OtherEvent>.map { …. }
	)
}

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fun <S, E> createStore(
    initial: S,
    eventsSource: Observable<E>,
    reducer: (S, E) -> S,
    transformer: ObservableTransformer<in Triple<S, S, E>, out E>
): Observable<S> {
  val state = behaviorSubjectDefault(initial)
  val events = behaviorSubject<E>()
  eventsSource.subscribe(events::onNext)
  events.withLatestFrom(state) { ev, oldState ->

charlag

val state = BehaviourSubject.create<State>()

nameInput.withLatestFrom(state) { name, state ->
 state.copy(name = name) 
}
.subscribe(state)

checkBoxChecks.withLatestFrom(state) { сbState, state →thLa
 state.copy(checkBoxCheched = cbState) 
}

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val viewInput = Observable.combineLatest(
	nameInput.startWith(“”),
	checkBoxChecks.startWith(false)
) { name, selected → State(name, selected) }

val dataFromDb = database.dao().loadById(…).map { dataFromDb → State(…) }

val state = Observable.merge(viewInput, dataFromDb)

charlag

val showToast: Observable<Unit>
//...
val showToastSubject = PublishSubject.create<Unit>()
showToast = showToastSubject
val errorEffect = ObservableTransformer<Triple<State, State, Event>, Event> { upstream ->
	upstream.ofEventType<ServerResponseEvent>.switchMap { (_, _, event) →
		if (!event.isSuccessful) showToastSubject.onNext(Unit)
		Observable.empty()
	}
}