protocol ArrayClippable { static func clipArray(_ array: inout Array<Self>, min: Self, max: Self) } extension ArrayClippable { static func clippedArray(_ array: Array<Self>, min: Self, max: Self) -> Array<Self> { var ret = array Self.clipArray(&ret, min: min, max: max) return ret } } extension Array where Element : ArrayClippable { mutating func clip(min: Element, max: Element) { Element.clipArray(&self, min: min, max: max) } func clipped(min: Element, max: Element) -> Array<Element> { return Element.clippedArray(self, min: min, max: max) } }