[swift-evolution] [Discussion] Removing tuple labels from the type signature

[David Hart]

I'm going to start work on a proposal to treat them as the same type.

> On 04 Feb 2016, at 19:57, Maximilian Hünenberger via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Is there a reasoning behind treating (Int, Int) and (lhs: Int, rhs: Int) as separate types?
> 
> Should it be treated as the same type as the proposal suggests?
> 
> Is there a connection to your tuple splat proposal?
> 
> Thank you in advance for clarification :)
> - Maximilian
> 
>>> Am 04.02.2016 um 18:27 schrieb Chris Lattner via swift-evolution <swift-evolution at swift.org>:
>>> 
>>> 
>>> On Feb 4, 2016, at 1:10 AM, David Hart via swift-evolution <swift-evolution at swift.org> wrote:
>>> 
>>> Before I start working on a proposal, I’d like to understand the problem in detail. Can someone help me understand why parts of the language treats tuple labels as type and other not?
>>> 
>>> let a: (lhs: Int, rhs: Int) = (4, 5) // works
>> 
>> This is supposed to work because of an implicit conversion.
>> 
>>> (4,5).dynamicType == (lhs: 2, rhs: 6).dynamicType // true
>> 
>> This is not supposed to behave this way.  The bug here is that we’re not encoding tuple labels in the metadata record for tuples.
>> 
>>> But:
>>> 
>>> [(lhs: 3, rhs: 5)] == [(1,2)]
>>> // Binary operator ‘==‘ cannot be applied to operands of type ‘[(las: Int, rhs: Int)]’ and ‘[(Int, Int)]’
>> 
>> This is correctly rejected.
>> 
>>> [(lhs: 3, rhs: 5)].dynamicType == [(1,2)].dynamicType
>>> // Binary operator ‘==‘ cannot be applied to operands of type ‘Array<(las: Int, rhs: Int)>.Type’ and ‘Array<(Int, Int)>’
>> 
>> This is correctly rejected.
>> 
>> 
>>> And:
>>> 
>>> struct Foo<T> {
>>> 	let bar: T
>>> }
>>> 
>>> var foo1 = Foo(bar: (4, 5))
>>> var foo2 = Foo(bar: (lhs: 4, rhs: 5))
>>> foo1 = foo2
>>> // Cannot assign value of type ‘Foo<(las: Int, res: Int)>’ to type ‘Foo<(Int, Int)>’
>> 
>> This is correctly rejected.
>> 
>>> But:
>>> 
>>> foo1.dynamicType == foo2.dynamicType // true
>> 
>> Same problem: reflection metadata isn’t being encoded, so these end up looking like they have the same dynamic type, when they shouldn’t.
>> 
>> -Chris
>> 
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