aubreylouw

/* unzip decomposes a list of pairs into a pair of lists.
   * The recursive case illustrates pattern-matching the result of the
   * recursive call in order to apply an operation to the elements.
   */
def unzip [X,Y] (ps:List[(X,Y)]) : (List[X], List[Y]) = ps match {
  case Nil      => (Nil, Nil)
  case (x, y) :: qs => {
    val (xs, ys) = unzip (qs)
    (x :: xs, y :: ys)
  }

aubreylouw

def duplicateN [X] (n:Int, xs:List[X]) : List[X] = (n, xs) match {
    case (n, xs) if n < 0 => throw new RuntimeException ("illegal op: negative N")
    case (_, Nil)         => xs
    case (0|1, xs)        => xs
    case (_, h::t)        => (h::Nil) ::: copyN(n-1, h::Nil) ::: copyN(n,t)
}

aubreylouw

/* Not tail recursive. */
  def reverseSlow [X] (xs:List[X]) : List[X] = xs match {
    case Nil => Nil
    case y :: ys => reverseSlow (ys) ::: List (y)
  }

  /* Tail recursive. */
  def reverseFast [X] (xs:List[X]) : List[X] = {
    def aux (xs:List[X], result:List[X]) : List[X] = xs match {
      case Nil => result

aubreylouw

Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
    (ByVal lpClassName As String, _
    ByVal lpWindowName As String) As Long

Public Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
    (ByVal hWnd1 As Long, ByVal hWnd2 As Long, _
    ByVal lpsz1 As String, ByVal lpsz2 As String) As Long

Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
    (ByVal hwnd As Long, ByVal wMsg As Long, _