[swift-evolution] [Discussion] Zero-element tuple glitch

[Vladimir.S]

On 04.07.2016 0:47, Anton Zhilin via swift-evolution wrote:
> Vladimir.S via swift-evolution <swift-evolution at ...> writes:
>
>> On 03.07.2016 23:53, Anton Zhilin via swift-evolution wrote:
>>> let x = (Int, Int)(1, 2)  //=> (1, 2)
>>> let y = (Int)(1)          //=> 1
>>> let z = ()()              // error :(
>>>
>>> Am I requesting too much from type checker?
>>
>> As I understand, because () is Void, you can't have anything additional
> for
>> it. It is just Void, like you write 'let z = Void Void'. I.e. only 'let
> z =
>> ()' allowed.
>
> In the example, that's how I expect that to parse:
>
> let z = ().init()  // just demo, does not compile
>
> I mean, first () is type, and second () is its initializer.
>
> By the way, this is one thing that Void can do, but () cannot.
> Are there any others?
>

I believe in this case () is playing a role of instance of type Void, i.e. 
empty tuple. I don't think you can expect ().init()

Also:
func f(_ x: ())->() {}
f(())
//f(Void) // argument passed to call that takes no arguments

And just some fun:

let x1 : Void
//let x2 : Void = Void // cannot convert value of type 'Void.Type' (aka 
'().Type') to specified type 'Void' (aka '()')
let x3 : ()
let x4 : () = ()
let x5 : Void = ()
//let x4 : () = Void  // cannot convert value of type 'Void.Type' (aka 
'().Type') to specified type '()'

print(().dynamicType) // ()
print(().self) // ()
// print("Void.dynamicType = ", Void.dynamicType) // '.dynamicType' is not 
allowed after a type name
print(Void.self) // ()
print(().dynamicType == Void.self) // true


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