Dice.swift

import Foundation

extension Array {

	func random() -> Element {
		return self[Int(arc4random_uniform(UInt32(self.count)))]
	}

}

struct Dice<T> {

	let faces: [T]

	init(_ first: T, _ second: T, _ others: T...) {
		self.faces = [first, second] + others
	}

	func roll() -> T {
		return faces.random()
	}

	func roll() -> T? {
		let optionalFaces = faces.map { Optional.Some($0) } + [Optional.None]
		return optionalFaces.random()
	}

}

extension Dice where T: ForwardIndexType {

	init(_ range: Range<T>) {
		self.faces = [T](range)
	}

}

let dice = Dice(1 ... 6)
for i in 0 ..< 100 {
	print(dice.roll() as Int)
}

let names = Dice("Alice", "Bob", "Charlie")
for i in 0 ..< 100 {
	print(names.roll() ?? "nobody")
}