inState<State>

The first concept of the DSL we learn is inState:

class ItemListStateMachineFactory(
    private val httpClient: HttpClient
) : FlowReduxStateMachineFactory<ListState, Action> {

    init {
        spec {
            initializeWith { Loading }

            inState<Loading> {
                ...
            }
        }
    }
}

inState<Loading> is just an “entry point” that describes that anything inside this block should only be executed while the state machine is currently in a state that matches the given class. Next, let’s discuss what an inState block can contain as triggers to actually “do something”:

1. onEnter: Triggers whenever we enter that state
2. on<Action>: Triggers whenever we are in this state and the specified action is triggered from the outside by calling FlowReduxStateMachine.dispatch(action).
3. collectWhileInState(flow): You can subscribe to any arbitrary Flow while your state machine is in that state.

Additionally, onEnterStartStateMachine() and onActionStartStateMachine() can be placed inside an inState { ... } block, but we will talk about these advanced concepts that are useful for composing business logic later.

Let’s take a closer look at three basic elements, onEnter, on<Action> and collectWhileInState, as we build our state machine.