FizzBuzz implementation in Swift

FizzBuzz.swift

let numbers = AnySequence { () -> AnyGenerator<Int> in
    var i = 1
    return anyGenerator {
        return i++
    }
}.lazy

let fizzes = numbers.map { $0 % 3 == 0 ? "Fizz" : "" }
let buzzes = numbers.map { $0 % 5 == 0 ? "Buzz" : "" }

let pattern = zip(fizzes, buzzes).lazy.map { (fizz, buzz) in fizz + buzz }

let fizzbuzz = zip(pattern, numbers).lazy.map { (p, n) in p.isEmpty ? String(n) : p }

for fb in fizzbuzz.prefix(31) {
    print(fb)
}

See also http://www.obqo.de/blog/2015/11/25/true-lazy-sequences/