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 >
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