htc_3_10.swift

let firstReducer: Reducer = { state, event in
    var state = state
    switch event {
    case .newUserWasLoaded(let user):
        state.user = user
    default:
        return state
    }
    return state
}
let secondReducer: Reducer = { state, event in
    var state = state
    switch event {
    case .newsEvents:
        state.newsState?.step = .loading
    default:
        return state
    }
    return state
}
let resultReducer = combine(firstReducer, secondReducer)
let initialState = AppState(user: User(id: ""), newsState: NewsState(user: User(id: ""), step: .initial))
let firstMutation = resultReducer(initialState, .newUserWasLoaded(User(id: 1)))
let secondMutation = resultReducer(firstMutation, .newsEvents(.loadData))
print(secondMutation.user.id)
print(secondMutation.newsState!.step)
// Console output:
// 1
// loading