linean

fun <STATE, EVENT> ViewModel.StateReducerFlow(
    initialState: STATE,
    reduceState: (STATE, EVENT) -> STATE,
): StateReducerFlow<STATE, EVENT> = StateReducerFlowImpl(initialState, reduceState, viewModelScope)

linean

private class StateReducerFlowImpl<STATE, EVENT>(
    initialState: STATE,
    reduceState: (STATE, EVENT) -> STATE,
    scope: CoroutineScope
) : StateReducerFlow<STATE, EVENT> {

    private val events = Channel<EVENT>()

    private val stateFlow = events
        .receiveAsFlow()

linean

interface StateReducerFlow<STATE, EVENT> : StateFlow<STATE> {
    fun handleEvent(event: EVENT)
}

linean

class ViewModel {

    private val events = Channel<Event>()

    val state = events.receiveAsFlow()
        .runningFold(State(), ::reduceState)
        .stateIn(viewModelScope, Eagerly, State())

    fun handleEvent(event: Event) {
        events.trySend(event)

linean

class ViewModel {

    private val events = Channel<Event>()

    val state = MutableStateFlow(State())

    init {
        events.receiveAsFlow()
            .onEach(::updateState)
            .launchIn(viewModelScope)

linean

sealed class Event {
    object Increment : Event()
    object Decrement : Event()
}

data class State(
    val counter: Int = 0
)

class ViewModel {