func map<T, U>(_: T?, f: @noescape (T) -> U) Haskell's fmap for Optionals. Declaration func map<T, U>(x: T?, f: @noescape (T) -> U) -> U? func map<S : SequenceType, T>(_: S, transform: (S.Generator.Element) -> T) Return an Array containing the results of mapping transform over source. Declaration func map<S : SequenceType, T>(source: S, transform: (S.Generator.Element) -> T) -> [T] func map<C : CollectionType, T>(_: C, transform: (C.Generator.Element) -> T) Return an Array containing the results of mapping transform over source. Declaration func map<C : CollectionType, T>(source: C, transform: (C.Generator.Element) -> T) -> [T]