constructor.ts

  ...  
  actions$: BehaviorSubject<Action>;
  state$: BehaviorSubject<any>;

  constructor() {
    this.actions$ = new BehaviorSubject({ type: 'INIT' });
    const actionsOnQueue$: Observable<Action> = this.actions$.pipe(observeOn(queueScheduler));
    const reducer$: Observable<
      ActionReducer<any, any>
    > = new BehaviorSubject(reducerFactory(reducers));
    const withLatestReducer$: Observable<
      [Action, ActionReducer<any, Action>]
    > = actionsOnQueue$.pipe(withLatestFrom(reducer$));
    this.state$ = new BehaviorSubject({});

    const stateAndAction$: Observable<
      { state: any; action?: Action; }
    > = withLatestReducer$.pipe(
      scan(reduceState, { state: {} }
      )
    );

    stateAndAction$.subscribe(({ state }) => {
      this.state$.next(state);
    });
  }
  ...