sort(by:) is probably the easiest right now, other than conforming Foo to Comparable.
sort { $0.numbers[0] < $1.numbers[0] }
There's also this pitch: Map Sorting
sort(by:) is probably the easiest right now, other than conforming Foo to Comparable.
sort { $0.numbers[0] < $1.numbers[0] }
There's also this pitch: Map Sorting