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Scala example source code file (FingerTreeUsage.scala)

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

Learn more about this Scala project at its project page.

Java - Scala tags/keywords

app, fingertreeusage, int, list, sizereducer, some, stream, unitreducer

The FingerTreeUsage.scala Scala example source code

package scalaz
package example

import collection.immutable.Stream


object FingerTreeUsage extends App{
  import FingerTree._
  import std.anyVal._

  def streamToTree[A](stream: Stream[A]): FingerTree[Int, A] = stream.foldLeft(empty(SizeReducer[A])) {
    case (t, x) => (t :+ x)
  }

  val intStream = Stream.from(1)

  implicit def SizeReducer[A]: Reducer[A, Int] = UnitReducer(x => 1)

  val emptyTree = empty[Int, Int](SizeReducer[Int])

  assert(emptyTree.isEmpty)

  //prepending
  assert((2 +: 3 +: 4 +: emptyTree).toList == List(2, 3, 4))

  //appending
  assert((emptyTree :+ 2 :+ 3 :+ 4).toList == List(2, 3, 4))

  //folding
  assert(streamToTree(intStream.take(20)).foldRight(0)(_ + _) == (1 to 20).sum)

  //replace the first element of the tree
  assert((5 |-: streamToTree(intStream.take(3))).toList == List(5, 2, 3))

  //replace the last element of the tree
  assert((streamToTree(intStream.take(3)) :-| 5).toList == List(1, 2, 5))

  //appending two trees
  assert((streamToTree(intStream.take(5)) <++> streamToTree(Stream.from(6).take(5))).toStream == intStream.take(10))

  import std.option._

  //traversing the tree
  val traversedTree = streamToTree(intStream.take(10)).traverseTree[Option, Int, Int](i => Some(i * 2))
  assert(traversedTree.map(_.toStream).getOrElse(Stream.empty) == intStream.map(_ * 2).take(10))

  println(streamToTree(intStream.take(10)).traverseTree[Option, Int, Int](i => Some(i + 1)))
}

Other Scala examples (source code examples)

Here is a short list of links related to this Scala FingerTreeUsage.scala source code file:

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