Iterator.swift

// Create an interator class
class ElementIterator<T>: IteratorProtocol {

    typealias Element = T

    let element: T

    init(element: T) {
        self.element = element
    }

    func next() -> T? {
        return element
    }
}

// Create a protocol with default implementation to simplify using for custom classes
protocol Iterable {

    func makeIterator() -> ElementIterator<Self>
}

extension Iterable {

    public func makeIterator() -> ElementIterator<Self> {
        return ElementIterator(element: self)
    }
}

typealias ElementSequence = Sequence & Iterable

// Extend Double
extension Double: ElementSequence {}

struct Man {

    let name: String
    let age: Double
}

// Create a names and init men with default age
let names = ["Anton", "Artem", "Jeka"]
print(zip(names, 25).map(Man.init))