Scala example source code file (LazyOptionTTest.scala)

This example Scala source code file (LazyOptionTTest.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

apply, bindrec, functor, int, lazyoptionid, lazyoptiont, lazyoptiontlist, lazyoptionttest, monad, speclite

The LazyOptionTTest.scala Scala example source code

package scalaz

import scalaz.scalacheck.ScalazProperties._
import scalaz.scalacheck.ScalazArbitrary._
import std.AllInstances._

object LazyOptionTTest extends SpecLite {

  type LazyOptionTList[A] = LazyOptionT[List, A]

  checkAll(equal.laws[LazyOptionTList[Int]])
  checkAll(monadPlus.laws[LazyOptionTList])
  checkAll(bindRec.laws[LazyOptionTList])

  "tail recursive tailrecM" in {
    import Scalaz.Id
    type LazyOptionId[A] = LazyOptionT[Id, A]

    val times = 10000

    val result =
      BindRec[LazyOptionId].tailrecM[Int, Int] {
        i => LazyOptionT[Id, Int \/ Int](LazyOption.lazySome(if (i < 10000) \/.left(i + 1) else \/.right(i)))
      }(0)
    result.getOrElse(0) must_=== times
  }

  object instances {
    def functor[F[_] : Functor] = Functor[LazyOptionT[F, ?]]
    def monad[F[_] : Monad] = Monad[LazyOptionT[F, ?]]
    def bindRec[F[_] : Monad: BindRec] = BindRec[LazyOptionT[F, ?]]

    // checking absence of ambiguity
    def functor[F[_] : Monad] = Functor[LazyOptionT[F, ?]]
    def functor[F[_] : Monad: BindRec] = Functor[LazyOptionT[F, ?]]
    def apply[F[_] : Monad] = Apply[LazyOptionT[F, ?]]
    def bind[F[_] : Monad: BindRec] = Bind[LazyOptionT[F, ?]]
  }
}