[swift-evolution] [Pitch] merge types and protocols back together with type<Type, Protocol, ...>

[Adrian Zubarev]

'struct<>' does seem redundant unless it becomes subtypeable. If you want a struct which conforms to several protocols, protocol<> already covers this.
I think this is not correct. Lets check this example:

func foo(value: SomeProtocol) {

    if let a = value as? struct<StructA, SomeProtocol> { /* do something with a */ }

    else if let b = value as? struct<StructB, SomeProtocol> { /* do something with b */ }

}

In this scenario you’ll be able to access properties and functions from `StructA` or `StructB` which might not be covered by `SomeProtocol`. Everything is merged nicely into one instance. But you are right it depends on the use-case.



Btw, if we'd have separate class<> and struct<> - we'd be able to have method to separate reference type from value type. 
We can write now : print(c is protocol<>) 
and we'd can: 
print(c is class<>) 
print(c is struct<>) 

True, I didn’t thought about that effect at the first glance, thank you for the hint. I will add this to the draft proposal tomorrow.


-- 
Adrian Zubarev
Sent with Airmail

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20160513/4a9f75e9/attachment.html>