A little combinator to measure the time of side effects. YES, *side effects* for now

gistfile1.scala

object Chronograph {

  /** Chronon is the quantum of time, here in our silly computers it got be a Long */
  type Chronon = Long
  
  sealed case class TimeUnit(chrononsInSecond: Chronon, name:String, getTime: => Chronon)
  val Nanos = new TimeUnit(1e9.toLong, "ns",  System.nanoTime)
  val Micros = new TimeUnit(1e6.toLong, "μs", System.nanoTime*1000)
  val Millis = new TimeUnit(1e3.toLong, "ms", System.currentTimeMillis())

  type EllapsedTimeOf[A] = (A, Chronon, TimeUnit)

  /** Records the measures of time of the `f` computation */
  def chronograph[A,B](timer: TimeUnit)(f: (A => B)): A => EllapsedTimeOf[B] =
     a => chronometer(timer)(f(a))

  /** Measures times of the `u` computation*/
  def chronometer[A,B](timer: TimeUnit)(u: => B):EllapsedTimeOf[B] = {
    val start = timer.getTime
    val res = u
    val end = timer.getTime
    (u,end - start, timer)
  }
  
  def nanoChronograph[A,B](f:A => B): A => EllapsedTimeOf[B] = chronograph(Nanos)(f)
  def microChronograph[A,B](f:A => B): A => EllapsedTimeOf[B] = chronograph(Micros)(f)
  def millisChronograph[A,B](f:A => B): A => EllapsedTimeOf[B] = chronograph(Millis)(f)
}