canceling-effects.swift

extension Effect {
  func cancellable<Id: Hashable>(id: Id) -> Effect<Output> {
    return Deferred { () -> PassthroughSubject<Output, Failure> in
      cancellables[id]?.cancel()
      let subject = PassthroughSubject<Output, Failure>()
      cancellables[id] = self.subscribe(subject)
      return subject
    }
    .eraseToEffect()
  }
}

extension Effect where Output == Never {
  static func cancel<Id: Hashable>(id: Id) -> Effect {
    .fireAndForget { 
      cancellables[id]?.cancel()
      cancellables[id] = nil
    }
  }
}

private var cancellables: [AnyHashable: AnyCancellable] = [:]

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