[swift-evolution] [Planning][Request] "constexpr" for Swift 5

[John McCall]

> On Aug 2, 2017, at 12:17 PM, Félix Cloutier <felixcloutier at icloud.com> wrote:
> `[Int x N]` solves all of the problems that I mentioned, and I'm happy with that syntax. In fact, I'm championing its merits versus an approach that doesn't include the number of elements. :)
> 
> Unless I got things wrong this entire time, the proposed spelling <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20170731/038341.html> was `fixed [Int]`, with no mention of the number of elements.

I agree that an array with a dynamic, value-specific but fixed bound seems basically pointless.  It's more of a minor optimization hint than a real type.

John.


> 
> Félix
> 
>> Le 2 août 2017 à 09:00, John McCall <rjmccall at apple.com <mailto:rjmccall at apple.com>> a écrit :
>>> 
>>>> var foo = fixed [Int]()
>>>> for i in 0..<param {
>>>> 	foo.append(i)
>>>> }
>>> 
>>> Arrays can't work if elements don't have a fixed size. How big is an element in this example?
>> 
>> This is not the idea.  The idea is more like
>> 
>>   let n = ...
>>   var foo = [Int x n](repeating: 13)
>> 
>> The bound value is still fundamentally part of the type of the variable; it's just that the actual value is not known statically.
>> 
>> John.
> 

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