Hmm, I don't know. It also works with other nominal types. For example:
struct S {
var x: Int
var y: Int
}
let s1 = S(x: 0, y: 1)
let s2 = S(x: 2, y: 3)
let arr = [s1, nil, s2]
print(type(of: arr)) // Array<Optional<S>>
> Am 24.03.2017 um 11:30 schrieb Rien <r...@balancingrock.nl>:
>
> Btw, I just looked it up and it seems to me that inference only works for
> literals. Which probably means that tuples are out.
>
> Regards,
> Rien
>
> Site: http://balancingrock.nl
> Blog: http://swiftrien.blogspot.com
> Github: http://github.com/Balancingrock
> Project: http://swiftfire.nl
>
>
>
>
>
>> On 24 Mar 2017, at 11:22, Rien via swift-users <swift-users@swift.org> wrote:
>>
>> IMO this is a boundary problem.
>> How far do you want to go in letting the compiler deduce the actual type?
>> It is possible to make very elaborate constructs that would basically
>> default to a complex tuple/array/dictionary construct with only Any?’s in
>> them. (well, the dict would require a Hashable too)
>>
>> Besides, the recent discussion on compile times illustrates another angle to
>> this problem: if type inference is used extensively, compile times go to
>> infinite…
>>
>> So while I do not know if this is a bug or not, I would recommend not to use
>> it anyhow.
>>
>> Regards,
>> Rien
>>
>> Site: http://balancingrock.nl
>> Blog: http://swiftrien.blogspot.com
>> Github: http://github.com/Balancingrock
>> Project: http://swiftfire.nl
>>
>>
>>
>>
>>
>>> On 24 Mar 2017, at 11:08, Toni Suter via swift-users
>>> <swift-users@swift.org> wrote:
>>>
>>> Hi,
>>>
>>> If I declare a variable and initialize it with an array literal whose
>>> elements are integer literals and nil literals,
>>> the compiler will infer the type Array<Optional<Int>> for that variable:
>>>
>>> let arr = [1, nil, 3]
>>> print(type(of: arr)) // Array<Optional<Int>>
>>>
>>> However, that only works with nominal types such as Int and String. If I do
>>> the same thing with an array of tuples,
>>> I get a compile error:
>>>
>>> let arr = [(1, false), nil, (3, true)] // error: type of
>>> expression is ambiguous without more context
>>> print(type(of: arr))
>>>
>>> Why can't the compiler infer the type Array<Optional<(Int, Bool)>> in this
>>> example? Is there a reason for this or is it a bug?
>>>
>>> Thanks and best regards,
>>> Toni
>>>
>>> _______________________________________________
>>> swift-users mailing list
>>> swift-users@swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-users
>>
>> _______________________________________________
>> swift-users mailing list
>> swift-users@swift.org
>> https://lists.swift.org/mailman/listinfo/swift-users
>
_______________________________________________
swift-users mailing list
swift-users@swift.org
https://lists.swift.org/mailman/listinfo/swift-users
