Using 'Error' as a concrete type conforming to protocol 'Error' is not supported

[ratkins]

I'm attempting to write a protocol like this:

protocol Response {}
protocol Resource {
    associatedtype ResponseType: Response
    var baseURL: URL { get }
    var path: String { get }
    var method: HTTPMethod { get }
    var headers: [String: String]? { get }
    var parameters: [String: Any]? { get }
    func parse(response: Data) -> Result<ResponseType, Error>
}

But I get the error Using 'Error' as a concrete type conforming to protocol 'Error' is not supported on the final line. I understand this is because of the way Result is declared as Result<T, Error : Error> ..., thus forcing the caller to provide a concrete Error subtype.

The problem I run into is that in my parse() method I would like to just throw up any errors produced by my JSON parsing library (or whatever.) But they're declared as Swift.Error, which means I can't do that.

I understand from reading other issues that if Result was declared Result<T> (and just implied Swift.Error as its error type) it'd degenerate to just an Either and the maintainers don't want that.

But is there a neat way I can get around this without having to explicitly wrap every Error subtype my parse() might throw?

[ikesyo]

#198 would be the help.

[ratkins]

So, in practice, the answer to the question in my last sentence is "No, just declare parse to return func parse(response: Data) -> Result<ResponseType, AnyError>", which works fine in practice.

[revolter]

I don't understand how does #198 help with this.

[ratkins]

As I said above, I needed to change the return type from Result<..., Error> to Result<..., AnyError>.