New Swift array syntax and Generic function

Question

Since Xcode beta 3, we can write [int] as short hand for Array<Int>.

So we should write this:

func commonElements <T, U where T: Sequence, U: Sequence,
    T.GeneratorType.Element: Equatable,
    T.GeneratorType.Element == U.GeneratorType.Element>
    (lhs: T, rhs: U) -> [T.GeneratorType.Element] {
        var result = [T.GeneratorType.Element]()
        for lhsItem in lhs {
            for rhsItem in rhs {
                if lhsItem == rhsItem {
                    result += rhsItem
                }
            }
        }
        return result
}
commonElements([1, 2, 3, 4], [2, 4, 6])

For a reason I don't understand, Xcode doesn't accept the short syntax to initialize result array but accept its long equivalent Array<T.GeneratorType.Element>().

Am I missing something?

JeremyP · Accepted Answer · 2014-07-16 10:12:27Z

3

Maybe the compiler is getting confused. This works though

var result: [T.GeneratorType.Element] = []

and is more readable IMO.

answered Jul 16, 2014 at 10:12

JeremyP

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2 Comments

clmntcrl Over a year ago

I think it's a compiler bug, the next Xcode beta may solve it. (NB: [Type]() is the syntax Apple uses in its Swift doc to declare empty array.)

JeremyP Over a year ago

@clmntcrl Apple uses both notations []() appears 12 times in The Swift Programming Language and [] appears 7 times.

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