Why does Swift has a restriction for single argument tuple with naming parameter?

[lolgear (Dmitry Lobanov)]

I am speaking of

typealias RequestParameters = (url: URL) // Not allowed

It would be really convenient to me if I could define a tuple ( single? ) with one argument and with a naming parameter.

Could we move forward with this and discuss disadvantages/advantages of this feature? It seems easy to implement...

Workaround

As a workaround for this feature, we could define a tuple with latest parameter as Void. Ugly, but we could.

typealias RequestParameters = (url: URL, Void) // Not allowed

This example reminds me about [NSArray arrayWithValues: first, second, third, nil]

[Tino]

Some links:

Single-element labeled tuples?

Continuing the discussion from More consistent function types: What are the reasons that single-element tuples are forbidden from the language? For example, tuple labels can help clarify the role of a single discardable return value. var counter = 1 var global: UInt = 0 @discardableResult func bar(_ x: UInt) -> (counter: Int) { // error: cannot create a single-element tuple with an element label global += x defer { counter += 1 } return counter }

Roadmap for and state of single element tuple types?

I have probably missed out on some information, and would appreciate pointers to such, regarding the following.

Some background from another thread

My conclusion from reading that entire thread, is that the preferred way to untangle the current tuple-type-related mess would be to … … and I'm very much in favor of this solution, even though it would … The default toolchain of Xcode 10 beta and versions up to the most recent dev snapshot (2018-06-14), has some new behavior that seems to su…