An example of a memoization function and a timing function.

gistfile1.scala

def memoize[T,U](fn: (T, T => U) => U) = {
  var map = HashMap.empty[T,U]
  def memoedFn(t: T): U = { map.getOrElseUpdate(t, fn(t, memoedFn)) }
  memoedFn _
}

val memoedFib = memoize((i: Long, rec: Long => Long) => i match { case x @ (0|1) => x; case x => rec(x-1) + rec(x-2)})

def time(fn: => Unit) = {
  val start = System.currentTimeMillis()
  fn
  System.currentTimeMillis() - start
}

time {
  List(1,2,3) map (_ + 5)
}