sequence-generators-lazy.swift

//: Playground - noun: a place where people can play

for i in 1...5 {
    print(i)
}

var range = Range(start: 1, end: 6)
var generator = range.generate()
while let i =  generator.next() {
    print(i)
}

class Fibo : SequenceType {
//    func generate() -> FiboGenerator {
//        return FiboGenerator()
//    }
    
    func generate() -> AnyGenerator<Int> {
        var c = 0
        var n = 1
        return anyGenerator {
            let ret = c
            c = n
            n = n + ret
            return ret
        }
    }
    
}

class FiboGenerator : GeneratorType {
    var c = 0 , n = 1
    typealias Element = Int
    func next() -> FiboGenerator.Element? {
        let ret = c
        c = n
        n = n + ret
        return ret
    }
}

for i in Fibo().prefix(10) {
    print(i)
}



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

var fizzes = numbers.map { ($0 % 3 == 0) ? "Fizz" : "" } // ["", "", "Fizz"]
var buzzes = numbers.map { ($0 % 5 == 0) ? "Buzz" : "" }
var sevens = numbers.map { ($0 % 7 == 0) ? "Sevens" : "" }
var pattern = zip(fizzes, buzzes).lazy.map { (fizz, buzz) in fizz+buzz }
var pattern2 = zip(pattern, sevens).lazy.map { (fizzbuzz, sevens) in fizzbuzz+sevens }

var fizzbuzz = zip(pattern2, numbers).lazy.map { (p,n) in p.isEmpty ? String(n) : p }

for i in fizzbuzz.prefix(16) {
    print(i)
}