lots and time

benchmark_utils.scala

// Borrowed from 
// http://stackoverflow.com/questions/3102872/what-is-the-fastest-way-to-sum-a-collection-in-scala/3103800#3103800

def time[F](f: => F) = {
  val t0 = System.nanoTime
  val ans = f
  printf("Elapsed: %.3f\n",1e-9*(System.nanoTime-t0))
  ans
}

def lots[F](n: Int, f: => F): F = if (n <= 1) f else { f; lots(n-1,f) }

def bench[F](what:String, n:Int, f: => F) = {
  println(what + ": warming...")
  lots(n, f)
  time(what, f)
}

def bench[F,G](what:String, n:Int, fwarm: => F, f: => G) = {
  println(what + ": warming...")
  lots(n, fwarm)
  time(what, f)
}

// use like this:
// lots(3, time( lots(100, somefunction ) )

// also: http://wikis.sun.com/display/HotSpotInternals/MicroBenchmarks
// java -XX:+PrintCompilation -cp "classes;/path/to/lib/scala-library.jar" ClassName