Interactors.RecipeList.swift

public class RecipeList {

    public let sortDescriptor: SafeObserver<SortDescriptor>
    public let recipes: SafeSignal<[Recipe]>

    public init(client: SafeClient, category: Category) {

        let recipes = client
            .response(for: API.Recipe.all(category: category))
            .shareReplay(limit: 1)

        let sortDescriptor = SafePublishSubject<SortDescriptor>()

        self.recipes = sortDescriptor
            .flatMapLatest { sortDescriptor in
                return recipes.map { $0.sort(by: sortDescriptor) }
            }
            .shareReplay(limit: 1)
        
        self.sortDescriptor = sortDescriptor.toObserver()
    }
}