SignalProducer+Codable.swift

extension SignalProducer where Value == (Data, URLResponse), Error == AnyError {
    func jsonDecode<T: Decodable>(decoder: JSONDecoder = JSONDecoder()) -> SignalProducer<T, AnyError> {
        return attemptMap({ data, _ in
            try decoder.decode(T.self, from: data)
        })
    }
}

extension SignalProducer where Value: Encodable, Error == AnyError {
    func jsonEncode(encoder: JSONEncoder = JSONEncoder()) -> SignalProducer<Data, AnyError> {
        return attemptMap({ value in
            try encoder.encode(value)
        })
    }
}