macbaszii

Optional(20) >>- half >>- half >>- half
// => .None

macbaszii

// For Optional
func >>-<T, U>(a: T?, f: T -> U?) -> U?

// For Array
func >>-<T, U>(a: [T], f: T -> [U]) -> [U]

macbaszii

Optional(3) >>- half
// .None
Optional(4) >>- half
// 2
Optional.None >>- half
// .None

macbaszii

func half(a: Int) -> Int? {
  return a % 2 == 0 ? a / 2 : .None
}

macbaszii

infix operator >>- { associativity left }

func >>-<T, U>(a: T?, f: T -> U?) -> U? {
  return a.flatMap(f)
}

macbaszii

func curriedTimes(a: Int)(b: Int) -> Int {
  return a * b
}

curriedTimes <^> Optional(5) <*> Optional(3)

macbaszii

curriedAddition <^> Optional(2) <*> Optional(3)

macbaszii

func curriedAddition(a: Int)(b: Int) -> Int {
  return a + b
}

curriedAddition <^> Optional(2) <^> Optional(3)
// => COMPILER ERROR: Value of optional type '(Int -> Int)? not unwrapped; did you mean to use '!' or '??'

macbaszii

[ { $0 + 3 }, { $0 * 2 } ] <*> [1, 2, 3]
// => [ 4, 5, 6, 2, 4, 6 ]

macbaszii

Optional.Some({ $0 + 3 }) <*> Optional.Some(2)
// => 5