fibonacci_streams.scala

/** This is so slick. 
 *  When working with Streams, use val instead of def so that memoization is enabled by default.
 *  
 *  Also see See http://derekwyatt.org/2011/07/29/understanding-scala-streams-through-fibonacci/ 
*/
import scala.math.BigInt
lazy val fibs: Stream[BigInt] = BigInt(0) #::
                                BigInt(1) #::
                                fibs.zip(fibs.tail).map { n => n._1 + n._2 }