[swift-evolution] Subclass Existentials

Goffredo Marocchi panajev at gmail.com
Sun Jan 29 14:39:38 CST 2017


Can I say that I dearly miss the old Any<> syntax? Oh well...

Sent from my iPhone

> On 29 Jan 2017, at 18:41, Austin Zheng via swift-evolution <swift-evolution at swift.org> wrote:
> 
> The "class comes first" requirement made more sense when the proposed syntax was still "Any<T, U, V>", intentionally mirroring how the superclass and conformances are declared on a class declaration (the archives contain more detailed arguments, both pro and con). Now that the syntax is "T & U & V", I agree that privileging the class requirement is counterintuitive and probably unhelpful.
> 
> Austin
> 
>> On Jan 29, 2017, at 10:37 AM, Matt Whiteside via swift-evolution <swift-evolution at swift.org> wrote:
>> 
>> Thanks for writing this proposal David.  
>> 
>>> On Jan 29, 2017, at 10:13, Xiaodi Wu via swift-evolution <swift-evolution at swift.org> wrote:
>>> 
>>> As Matthew mentioned, the rules can certainly later be relaxed, but given that this proposal has the compiler generating fix-its for subclasses in second position, is there a reason other than stylistic for demanding MyClass & MyProtocol instead of MyProtocol & MyClass?
>>> 
>>> From a naive perspective, it seems that if the compiler understands my meaning perfectly, it should just accept that spelling rather than complain.
>> 
>> I had that thought too.  Since ‘and’ is a symmetric operation, requiring the class to be in the first position seems counter-intuitive.
>> 
>> -Matt
>> 
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