>>=, the "monad" bind operator, in Swift

gtgteq.swift

infix operator >>= {
    associativity left
    precedence 160
}

func >>=<S: SequenceType, T>(source: S, transform: S.Generator.Element -> [T]) -> [T] {
    return flatMap(source, transform)
}
func >>=<C : CollectionType, T>(source: C, transform: (C.Generator.Element) -> [T]) -> [T] {
    return flatMap(source, transform)
}
func >>=<T, U>(x: T?, f: (T) -> U?) -> U? {
    return flatMap(x, f)
}

// [1,2,3] >>= { (i: Int) -> [Int] in [i, -i] }
// => [1, -1, 2, -2, 3, -3]

// (6 as Int?) >>= { $0 * 7 } // => Optional(42)
// (nil as Int?) >>= { $0 * 7 } // => nil
// (10 as Int?) >>= { $0 == 10 ? nil : $0 + 1 } // => nil