Current Tutorial on Combining Reducers

[Senbazuru1075]

Hello,

I'm new to functional programming and am having trouble combining reducers. I am using pointfree for a project. I'm trying to combine to reducers. Essentially when the onboarding complete button is pressed the startup view store holding that domain should set state to switch to a destination view such as signup.

However, I am receiving a build expression error requiring Onboarding.State and AppStartup.State to be equivalent as well as their actions.

I'm not sure how to solve this error. I looked in the discussion for solutions. It looks like an EmptyReducer is necessary. I am a beginner so I'd like some help.

Here is the code:

struct Startup: ReducerProtocol {
    struct State: Equatable {
        static func == (lhs: Startup.State, rhs: Startup.State) -> Bool {
            lhs.stateOfView == rhs.stateOfView
        }
        
        @AppStorage("stateOfView") var stateOfView: AppEntryState = .onboarding
        var stateOfOnboarding = Onboarding.State(completedOnboarding: false)
    }
    
    enum AppEntryState: String, CaseIterable {
        case authorized
        case login
        case signup
        case onboarding
    }
    
    enum Action: Equatable {
        case switchToDestinationView(AppEntryState)
        case changeToSignUp(Onboarding.Action)
    }
    
    var body: some ReducerProtocol<State, Action> {
      Reduce(self.core)
      Onboarding()
    }

    func core(state: inout State, action: Action) -> EffectTask<Action> {
        switch action {
        case .switchToDestinationView(let destinationView):
            state.stateOfView = destinationView
            return .none
        case .changeToSignUp(.didPressCompletionButton):
            state.stateOfView = .signup
            return .none
        }
    }
}

struct Onboarding: ReducerProtocol {
    struct State: Equatable {
        static func == (lhs: Onboarding.State, rhs: Onboarding.State) -> Bool {
            lhs.completedOnboarding == rhs.completedOnboarding
        }
        
        @AppStorage("completedOnboarding") var completedOnboarding: Bool = false
        
    }
    enum Action: Equatable {
        case didPressCompletionButton
    }
    
    func reduce(into state: inout State, action: Action) -> EffectTask<Action> {
        switch action {
        case .didPressCompletionButton:
            state.completedOnboarding = true
            return .none
        }
    }
}

[stephencelis]

@Senbazuru1075 Your Onboarding reducer works on a different domain than your AppStartup reducer, so they can't be combined till the domains match. Your AppStartup reducer already has slots in state and action for Onboarding, though, which means you just need to use the Scope operator to describe where in the parent route things:

var body: some ReducerProtocol<State, Action> {
  Reduce(self.core)
  Scope(state: \.stateOfOnboarding, action: /Action.changeToSignUp) {
    Onboarding()
  }
}