MVI vs MVVM

ExampleViewModel.kt

// Here counter can show 1 after incrementCounter is called
class ExampleViewModel : ViewModel() {
  private val _counter = MutableLiveData(0)

  init {
    viewModelScope.launch(Dispatchers.IO) {
      // Thread 1
      delay(500)
      _counter.postValue(_counter.value?.plus(1))
    }
  }

  fun incrementCounter() = viewModelScope.launch(Dispatchers.IO) { // UI calls this
    // Thread 2
    _counter.postValue(_counter.value?.plus(1))
  }

  // Thread 1 reads 0
  // Thread 1 looses cpu
  // Thread 2 reads 0
  // Thread 2 looses cpu
  // Thread 1 writes 1
  // Thread 2 writes 1
}

// Here counter will always show 2 after incrementCounter called
class ExampleMviViewModel : ViewModel() {
  init {
    reduceState { state ->
      delay(500)
      state.copy(count = state.count + 1)
    }
  }
  
  fun incrementCounter = reduceState { state ->
    state.copy(count = state.count + 1)
  }
}