import Foundation

func add(_ lhs: Int, _ rhs: Int) -> Int {
    lhs + rhs
}

let addClosure: (Int, Int) -> Int
= { (lhs: Int, rhs: Int) -> Int in
    lhs + rhs
}

addClosure(20, 30)

func customAdd(_ lhs: Int, _ rhs: Int, using function: (Int, Int) -> Int) -> Int{
    return function(lhs, rhs)
}

customAdd(20, 30, using: addClosure)

customAdd(20, 30, using: { (lhs: Int, rhs: Int) -> Int in lhs + rhs})

customAdd(20, 30) { (rhs, lhs) in
    rhs + lhs
}

customAdd(20, 30) { $0 + $1 }


let ages = [2, 3, 54, 24, 512, 63, 32]
ages.sorted(by: {(lhs: Int, rhs:Int) -> Bool in lhs < rhs})

ages.sorted(by: <)
ages.sorted(by: >)

func customAdd2(using function: (Int, Int) -> Int, _ lhs: Int, _ rhs: Int) -> Int{
    return function(lhs, rhs)
}

customAdd2(using: { (lhs, rhs) in lhs + rhs}, 20, 30)

customAdd(30, 10, using: +)

func doAddition(on value: Int, using function: (Int) -> Int) -> Int {
    function(value)
}

doAddition(on: 30) { (value) in
    value + 60
}

func add20To(value: Int) -> Int {
    value + 20
}

doAddition(on: 10, using: add20To(value:))