[swift-evolution] Variadic generics discussion

[Matthew Johnson]

> On May 31, 2016, at 3:39 PM, Austin Zheng <austinzheng at gmail.com> wrote:
> 
> (inline)
> 
> On Tue, May 31, 2016 at 1:34 PM, Matthew Johnson <matthew at anandabits.com <mailto:matthew at anandabits.com>> wrote:
> 
>> On May 31, 2016, at 3:25 PM, Austin Zheng <austinzheng at gmail.com <mailto:austinzheng at gmail.com>> wrote:
>> 
>> I have a proposal for #6 in the pipe, but there are actually some subtleties I have to work out (it's not as simple as just slapping a generic type signature on a let constant).
> 
> Cool.  Looking forward to reviewing a draft when it’s ready.
> 
>> 
>> I think #5 is just considered a 'bug' and doesn't need a proposal (it might actually be finished already; I saw some commits recently); same with #4. #7 is not very useful without variadic generics (it pretty much exists to allow tuples to conform to protocols, and tuples are inherently variadic).
>> 
> 
> Good to know 4 and 5 are considered bugs.  I know #4 is important for the standard library so I suppose that will ensure it is a priority soon enough.
> 
> I included #7 because it would still be nice to have for a number of reasons.  Maybe there is a way to pull it off for a handful of types that are known to the compiler.
> 
>> I wanted to take a stab at #2. 
> 
> Are you still thinking about this one or did you decide not to pursue it?
> 
> I think I'd like to try writing something up.
>  
> 
>> The core team has talked so much about #1 that I'd be surprised if they don't already have an idea as to how they want to do it, plus it's complicated for a number of reasons to get right. In such a case having the community push forward an alternate proposal would just be giving everyone more unneeded work.
> 
> Agree here as well.  I’ve avoided generics proposals mostly because I thought the core team was leading the charge on all them.  It now appears like that may not have been the right assumption across the board.  I wish we had a bit more visibility on this...
> 
> Yes, same. I'm going off this bullet point at the beginning of the generics manifesto:
> 
> "I hope to achieve several things: ... Engage more of the community in discussions of specific generics features, so we can coalesce around designs for public review. And maybe even get some of them implemented."
>  
> 
>> 
>> #3 seems semantically straightforward. AFAIK there's nothing a subscript can do that a getter and setter method can't do together, and methods can already be generic. A proposal shouldn't be hard to put together.
> 
> Agree.  Someone just needs to jump in and write it up.  :-)  If it had a chance of making it into Swift 3 I would do it right away, but it’s hard to tell...
> 
> I'd be happy to write up a proposal, especially if it's as straightforward as it seems.

Cool!  I’ll continue to play the role of providing as much feedback as I can…  :-)


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