[swift-evolution] Tuple conversion and type composition

[David Sweeris]

How about "&"? That way you can still define:
func + (lhs: (Int, Int), rhs: (Int, Int)) -> (Int, Int) {...}
Without either removing the ability to concatenate tuples, or having to annotate types all over the place to resolve the ambiguities. (I'd love to use a different operator for concatenating Arrays & Strings, as well, but that's not what this thread is about)

- Dave Sweeris

> On Feb 6, 2016, at 14:41, Andrew Bennett via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Thanks Tino, it would be good to come up with some alternatives for +.
> 
> I was initially thinking `(Int,Int) (Int,Int)` without operators. However I think this could potentially be a mistake. I like + as it's familiar with array operators.
> 
> As for the prevalence of tuples in the language, every function and value in Swift has a tuple in it. The associated values in an enum are a tuple. They are everywhere.
> 
> For some more examples have a look at the linked proposal :)
> 
> 
> On Sun, Jan 31, 2016 at 11:28 PM, Tino Heth <2th at gmx.de> wrote:
>>> I'd like a a way to concatenate tuple types together:
>>> 
>>> typealias ABCD = (A,B)+(C,D) // Same as (A,B,C,D)
>> 
>> I don't like the use of "+" for concatenation, but giving more power to tuples would be neat… you just need to find examples with convincing motivation ;-)
>> Obviously, the value of tuple-operation increases with the prevalence of tuples in language and libraries, so I wouldn't be surprised if their importance rises in the future (and maybe we can think of nice ways to combine tuple-related ideas).
>> 
>>> Also a way to allow tuples to be converted to other tuples that are the same when flattened:
>>> 
>>> (a,(b,c),d) as ((a,b),(c,d))
>> It would be cool if such a concept ("compiler, please check if those two types have a compatible memory-layout, and if that is the case, let me use them interchangeable when I tell you to do so) could be extended to structs — that could solve the problem of different implementations of fundamental types nicely.
>> 
>> That leads me to an unrelated thought:
>> It seems to me there is a duality between methods and closures on one side, and structs and tuples on the other — tuples feel very much like anonymous structs (restricted by the fact that you cannot add methods like custom getters & setters). It's not related to you proposal, but I wonder if there are implications visible from this point of view...
>> 
>> Tino
> 
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