Adding a `fold` method

[deanWombourne]

I have a few situations where I need to convert a Result to a common type, and looking at other languages fold seems to exist.

Essentially, this:

public extension Result {

    /// Convert either a success or failure into type `U`
    public func fold<U>(success: (Value) throws -> U, failure: (Error) throws -> U) rethrows -> U {
        switch self {
        case .success(let value): return try success(value)
        case .failure(let error): return try failure(error)
        }
    }
}

Good idea / bad idea?

[deanWombourne]

(Similar to recover / ?? except I want to map Value or Error to a new type, U)

[deanWombourne]

Wait - is this just the same as analysis?

[mdiep]

Yes, this is analysis.

[deanWombourne]

NICE. You mind if I raise a PR to add throws / rethrows to it?

[mdiep]

Why would you want that?