Reduce1

Reduce1.swift

#if swift(>=3.0)
extension Sequence {
	func reduce(combine: @noescape (Iterator.Element, Iterator.Element) throws -> Iterator.Element) rethrows -> Iterator.Element? {
		var iterator = makeIterator()
		guard var result = iterator.next() else { return nil }
		while let element = iterator.next() {
			result = try combine(result, element)
		}
		return result
	}
}
#else
extension SequenceType {
	func reduce(@noescape combine: (Generator.Element, Generator.Element) throws -> Generator.Element) rethrows -> Generator.Element? {
		var generator = generate()
		guard var result = generator.next() else { return nil }
		while let element = generator.next() {
			result = try combine(result, element)
		}
		return result
	}
}
#endif