import Foundation

infix operator **
func **<T, F, E>(f: @escaping ((E) -> F), g: @escaping ((T) -> E)) -> ((T) -> F) {
    return { f(g($0)) }
}

func addOne(i : Int) -> Int { return i + 1 }
func byTree(i: Int) -> Int { return i * 3 }


let array = (1...1000)

let time01 = Date()
array.map(addOne).map(byTree)               // 一番早い

let time02 = Date()
array.map { byTree(i: addOne(i: $0)) }      // あんまり

let time03 = Date()
array.map(addOne ** byTree)                 // かわらない

let time04 = Date()

print(time02.timeIntervalSince(time01))
print(time03.timeIntervalSince(time02))
print(time04.timeIntervalSince(time03))