gistfile1.scala

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

scala> ptime((1 to 8).size)
Elapsed: 0.000 sec
res4: Int = 8

scala> ptime((1 to 8).map(_ => 1).sum)
Elapsed: 0.001 sec
res5: Int = 8

scala> ptime((1 to 1000).map(_ => 1).sum)
Elapsed: 0.003 sec
res6: Int = 1000

scala> ptime((1 to 1000).size)
Elapsed: 0.000 sec
res7: Int = 1000

scala> ptime((1 to 1000000).map(_ => 1).sum)
Elapsed: 0.120 sec
res8: Int = 1000000

scala> ptime((1 to 1000000).size)
Elapsed: 0.000 sec
res9: Int = 1000000