struct FeedListView: View {
  @ObservedObject var state = FeedListState()
  
  var body: some View {
    List {
      ForEach(state.feeds, id: \.diffId) { feed in
        FeedCell(feed: feed)
      }
    }
  }
}

public class FeedListState: ReduxReducer, ObservableObject {  
  @Published var feeds: [Feed] = []
  
  public override func reduce(action: ReduxActionProtocol) {
    // Propagates `action` to the substate tree.
    // Setting `self.feeds` with new feeds triggers list UI reloading 
    // and SwiftUI will diff efficiently based on list identifier.
    feeds = feeds.map { $0.reduce(action: action) }
}

dispatch(action: FeedLikeAction(feed: feed))

public struct Feed {
  public var diffId = UUID()
  public let feedId: Int
  public let title: String
  public var isLiked: Bool { didSet { diffId = UUID() } }     
}

extension Feed: ReduxStateProtocol {
  @discardableResult
  public func reduce(action: ReduxActionProtocol) -> Self {
    // Makes the deep copy of self.
    var feedCopy = self    
    switch action {
    case let action as FeedLikeAction:
      // Reduces the `FeedLikeAction`.
      if feedId == action.feed.feedId {
        feedCopy.isLiked = !action.feed.isLiked
      }
    default: break
    }
    return feedCopy
  }
}