Some of these comparisons aren't great. The "Variable Number Of Arguments" example is better expressed in Swift with "reduce", and it's really comparing "summin

Some of these comparisons aren't great. The "Variable Number Of Arguments" example is better expressed in Swift with "reduce", and it's really comparing "summing an array", the varargs aspect is a minor detail of the example. The "Idiomatic Scala" example doesn't even declare a function with varargs! (yes, it uses one, but that's not really the point) The Swift function in the protocols example doesn't need to be generic, as the protocol doesn't have any associated types, and really ought to be a protocol extension regardless.