`compact` function in Swift

gistfile1.swift

func compact <A> (xs: [A?]) -> [A] {
  return xs.reduce([]) { accum, x in
    if let x = x {
      return accum + [x]
    }
    return accum
  }
}

var xs: [Int?] = [1, 2, nil, 3]
compact(xs) // => [1, 2, 3]