Extend "emptiness" test to Optional Collections

[Tino]

@charlieMonroe

I have an extension on Optional<Collection>

for in? optionalCollection {

This could come for almost free after SE-0143 is implemented: an Optional of a Sequence could itself be made to conform to Sequence. It would cost no new syntax. extension Optional: Sequence where Wrapped: Sequence {   func makeIterator() -> AnyIterator<Wrapped.Iterator.Element> {     switch self {     case .some(let sequence):       return AnyIterator(sequence.makeIterator())     case .none:       return AnyIterator { nil }     }   } } This would be more easily done than new syntax, …

Haven't checked the status for some time ;-)

But I guess the extension way is slower than if let - and although performance surely is good enough for nearly all cases, imho it's unfortunate when the most convenient way isn't the best way as well.