animal-shallow.state.ts

@State<AnimalsStateModel>({
  name: 'animals',
  defaults: {
    zebra: {
      food: ['leaves', 'bark'],
      name: 'zebra'
    },
    panda: {
      food: [],
      name: 'panda'
    }
  }
})
export class AnimalState {
  @Selector()
  public static zebraFood(state: AnimalsStateModel): string[] {
    const zebraFood = [...state.zebra.food];
    zebraFood.reverse();
  }

  @Action(Add)
  public add({ setState }: StateContext<AnimalsStateModel>, { payload }: Add) {
    setState((state: AnimalsStateModel) => ({
      ...state,
      zebra: {
        ...state.zebra,
        food: [ ...state.zebra.food, payload ]
      }
    }));
  }
}