[swift-evolution] Proposal: Contiguous Variables (A.K.A. Fixed Sized Array Type)

[Chris Lattner]

> On Jan 28, 2016, at 7:57 PM, Chris Lattner <clattner at apple.com> wrote:
> 
> 
>> On Jan 28, 2016, at 5:07 PM, Erica Sadun via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>> I find 
>> 
>> let values: (4 x Int) = (1, 2, 3, 4)
>> 
>> to be adequately cromulent. I believe this approach to be:
>> 
>> * Readable, even to someone unfamiliar with the syntax
>> * The parens before the assignment suggest something to do with tuples, and the numbers match the arity after the assignment
>> * The type is preserved in-place
>> * It's compact, elegant, simple
> 
> +1.  I like this syntax too, and with Joe’s other proposed extensions, it would all fit together nicely.  Anyone interested in writing up a proposal?

One other tweak worth considering: instead of subscript being defined on a tuple as returning a common type, a more modest proposal would be that subscript is defined on tuples that:

a) have no element labels.
b) all have the same element type.

This would solve the fixed size array use-case, be much easier to implement, and not have surprising performance issues promoting things to Any.  It is also consistent with the fact that we don’t infer the type of [Int(), Float()] to [Any].

-Chris

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