Redux implementation with Combine framework

Action.swift

/// This is peruly marker protocol,
/// it allows us to keep action list open, and add more actions
/// without breaking existed components.
///
/// Also sometimes it is nice to implement `Codable` or `Equatable`
public protocol Action {}

Reducer.swift

import Combine

/// Common Redux reducer contract
public typealias Reducer<State, Action, Environment> =
  (inout State, Action, Environment) -> AnyPublisher<Action, Never>?

Store.swift

import Combine

/// Redux store.
///
/// For information: https://swiftwithmajid.com/2019/09/18/redux-like-state-container-in-swiftui
///
/// `State` - module state.
/// `Action` - redux action for communication/modification state
/// `Environment` - abstraction for providing dependencies to reducer
public final class Store<State, Action, Environment>: ObservableObject {
  @Published
  public private(set) var state: State

  private let environment: Environment
  private let reducer: Reducer<State, Action, Environment>
  private let queue = DispatchQueue(label: "com.skybonds.redux.store", qos: .userInitiated)

  private var cancellables: Set<AnyCancellable> = []

  public init(
    initialState: State,
    reducer: @escaping Reducer<State, Action, Environment>,
    environment: Environment
  ) {
    self.state = initialState
    self.reducer = reducer
    self.environment = environment
  }

  public func send(_ action: Action) {
    queue.async {
      guard let effect = self.reducer(&self.state, action, self.environment) else {
        return
      }

      let cancellable = effect
        .sink(receiveValue: self.send)

      self.cancellables.insert(cancellable)
    }
  }
}