Scala example source code file (streams.scala)

This example Scala source code file (streams.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

app, app, array, array, int, none, none, some, stackoverflow, stream, test, test

The Scala streams.scala source code

object Test extends App {
  val s0: Stream[Int] = Stream.empty
  println(s0.take(1))
  println(s0.takeWhile(_ > 0))
  println

  val s1 = Stream.cons(1, Stream.empty)
  println(s1.toArray.deep)
  println(s1.take(1))
  println(s1.take(2))
  println(s1.drop(1))
  println(s1.drop(2))
  println(s1.drop(-1))
  println(s1.dropWhile(_ > 0))
  println

  val s2 = s1.append(Stream.cons(2, Stream.empty))
  println(s2.toArray.deep)
  println(s2.drop(1))
  println(s2.drop(2))
  println(s2.drop(-1))
  println(s2.dropWhile(_ > 0))
  println

  val s3 = Stream.range(1, 1000) //100000 (ticket #153: Stackoverflow)
  println(s3.length)

  // ticket #153
  def powers(x: Int) = if ((x&(x-1)) == 0) Some(x) else None
  println(s3.flatMap(powers).reverse.head)

  // large enough to generate StackOverflows (on most systems) 
  // unless the following methods are tail call optimized.
  val size = 100000

  // test tail recursive methods
  println(Stream.from(1).take(size).last)
  println(Stream.from(1).drop(size))
  println(Stream.from(1).filter(_ > size).take(5))
  println(Stream.from(1).take(size).forall(_ >= 0))
  println(Stream.from(1).exists(_ > size))
  Stream.from(1).take(size).foreach( x => () )
  println(Stream.from(1).take(size).foldLeft(0)(_ + _))
  val arr = new Array[Int](size)
  Stream.from(1).take(size).copyToArray(arr, 0)
}