let xs = "haskell"
map(toUpper, xs)

let xs               = [1, 2, 3, 4, 5]
let greaterThanThree = { x in x > 3 }
filter(greaterThanThree, list)

let xs       = [1, 2, 3]
let adds     = { (x: Int,y: Int) in x+y }
foldl1(adds, xs)

let process : ([Int]) -> Int = last .. reverse
let xs       = [1,2,3,4,5]
process(xs)

func _isPrime(n : Int) -> Bool {
    let array2ToN : Int->[Int]   = { x in Array(2...x) }
    let divisors  : Int->[Int]   = array2ToN .. Int.init .. ceil .. sqrt .. Double.init
    let isDivisible              = or .. map({ x in n % x == 0})
    let isNotPrime               = isDivisible .. divisors
    return !isNotPrime(n)
}
_isPrime(3)

let x : Int? = nil
maybeToList(x)

let xs: [Int?] = [1, nil, 3]
catMaybes(xs)