map.swift

// note the signature => (T?, T -> U?) -> U?
func flatMap<T, U>(value: T?, transform: T -> U?) -> U? {
  switch value {
  case .None: return .None
  case .Some(let contained): return transform(contained)
  }
}

// different from this => (T?, T -> U) -> U?
func map<T, U>(value: T?, transform: T -> U) -> U? {
  switch value {
  case .None: return .None
  case .Some(let contained): return Optional.Some(transform(contained))
  }
}