htc_3_18.swift

func transform(
    newsReducer: @escaping (NewsState, AppEvent) -> NewsState,
    appStateIntoNews: @escaping (AppState) -> NewsState
) -> Reducer {
    return { appState, appEvent in
        var appState = appState
        let newsState = appStateIntoNews(appState)
        let newNewsState = newsReducer(newsState, appEvent)
        appState.newsState = newNewsState
        return appState
    }
}