Another thought worth considering is an overload like this variant from the previous thread is already possible to write today, without variadic generics:
func sort(by areInIncreasingOrder: ((Element, Element) -> Bool)...) { ... }
people.sort(by:
{ $0.name < $1.name },
{ $0.age < $1.age },
{ $0.height < $1.height },
{ $0.salary < $1.salary })
I'm not sure where that fits in to the big picture for this proposal, but I do think it's a very noteworthy potential syntax for this topic: