Given this…
protocol P {
associatedtype T
}
let sequence: some Sequence<any P> = []
…I can understand why, because of the need for potentially multiple function specializations, this first filter compiles, but the second does not.
func function(_: some P) -> Bool {
true
}
var filtered = sequence.filter { function($0) }
filtered = sequence.filter(function) // Type 'any P' cannot conform to 'P' 🙃
That wouldn't bug me so much, except that
extension P {
var property: Bool { true }
}
filtered = sequence.filter(\.property)
compiles, generating "{ $0.property }".
I figure, if you've got a named function, it should get the same promotion—keeping it as a typed closure in this context isn't useful. Disagree?
Inspiration for my experimenting: I watched @hborla's excellent Embrace Swift generics from WWDC and thought it was lame that she had to use a for loop instead of
func feedAll(_ animals: [any Animal]) {
animals.forEach(feed)
}
