Scala example source code file (DListTest.scala)

This example Scala source code file (DListTest.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

bindrec, dlist, dlisttest, equal, int, isempty, monadplus, monoid, show, some, speclite, traverse, zip

The DListTest.scala Scala example source code

package scalaz

import std.AllInstances._
import syntax.equal._
import scalaz.scalacheck.ScalazProperties._
import scalaz.scalacheck.ScalazArbitrary._
import org.scalacheck.Prop.forAll

object DListTest extends SpecLite {

  checkAll(equal.laws[DList[Int]])
  checkAll(monoid.laws[DList[Int]])
  checkAll(zip.laws[DList])
  checkAll(traverse.laws[DList])
  checkAll(isEmpty.laws[DList])
  checkAll(bindRec.laws[DList])
  checkAll(monadPlus.strongLaws[DList])

  "DList append" ! ((0 to 100000).foldLeft(DList[Int]())(_ :+ _).toList must_== (0 to 100000).toList)

  "headOption, tailOption" ! forAll { (n: Int, d: DList[Int]) =>

    // Defined when appropriate?
    val nonempty = d.uncons(false, (_, _) => true)
    d.headOption.isDefined must_=== nonempty
    d.tailOption.isDefined must_=== nonempty

    // If defined, are values correct?
    val d0 = n +: d
    check(d0.headOption === Some(n)) // no Show instance, can't use must_===
    check(d0.tailOption === Some(d))

  }

  object instances {
    def equal[A: Equal] = Equal[DList[A]]
    def monoid[A] = Monoid[DList[A]]
    def monadPlus = MonadPlus[DList]
    def bindrec = BindRec[DList]
    def traverse = Traverse[DList]
    def zip = Zip[DList]
    def isEmpty = IsEmpty[DList]
  }
}