from sbde http://technically.us/git?p=spde.git

seq2RichRandom.scala

 trait Randoms {
    import scala.util.Random
    private val rand = new Random
    implicit def seq2RichRandom[K](seq: Seq[K]) = new RichRandom(seq)
    
    protected class RichRandom[K](seq: Seq[K]) {
      def random: K = seq((rand.nextFloat * seq.length).toInt)
    }
    
    
  }

scala> object MyImplicits extends Randoms
defined module MyImplicits

scala> import MyImplicits._
import MyImplicits._

scala> val l = List(1,2,3,4,5)
l: List[Int] = List(1, 2, 3, 4, 5)

scala> l.random
res0: Int = 4