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

import Foundation

let ns = [1,2,3,4,5]

// MARK: filter

var res1: [Int] = []
for n in ns {
    if n % 2 == 0 {
        res1.append(n)
    }
}
res1 // [2,4]

let res2 = ns.filter { $0 % 2 == 0 } // [2,4]

// MARK: map

var res3: [Int] = []
for n in ns {
    res3.append(n * 2)
}
res3 // [2,4,6,8,10]

let res4 = ns.map { $0 * 2 } // [2,4,6,8,10]

// MARK: flatMap

let cs = ["A,B,C", "D,E", "F"]
let res5 = cs.map { $0.componentsSeparatedByString(",") }
res5
let res6 = cs.flatMap { $0.componentsSeparatedByString(",") }
res6

func toInt(value: String) -> Int? {
    return value.toInt()
}

let one: String? = "1"

let mapOne = one.map { toInt($0) }
println(mapOne) // => Optional(Optional(1))

let flatMapOne = one.flatMap { toInt($0) }
println(flatMapOne) // => Optional(1)

// このようにflatMapはmapとよく似ていますが、
// 最初のArrayと要素数が変わったArrayが返ったり、多重のOptionalを避けられたりといった特徴があります。

// MARK: reduce

var res7 = 0
for n in ns {
    res7 += n
}
res7 // 15

ns.reduce(0, combine: +) // 15

// MARK: sample

func fizzbuzz(size: Int) -> [String] {
    func exec(n: Int) -> String {
        if n % 15 == 0 {
             return "FizzBuzz"
        } else if n % 5 == 0 {
            return "Buzz"
        } else if n % 3 == 0 {
            return "Fizz"
        } else {
            return String(n)
        }
    }

    return Array(1...size).map { exec($0) }
}

let sum = fizzbuzz(40).map({ $0.toInt() }).reduce(0) {
    if let i = $1 {
        return $0 + i
    } else {
        return $0
    }
}
sum // 412