Scala example source code file (OptionTest.scala)

This example Scala source code file (OptionTest.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, equal, first, last, max, min, monad, monoid, none, option, optiontest, order, semigroup, speclite

The OptionTest.scala Scala example source code

package scalaz
package std

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

object OptionTest extends SpecLite {

  checkAll("Option", order.laws[Option[Int]])
  checkAll("Option @@ First", order.laws[FirstOption[Int]])
  checkAll("Option @@ Last", order.laws[LastOption[Int]])
  checkAll("Option @@ Min", order.laws[MinOption[Int]])
  checkAll("Option @@ Max", order.laws[MaxOption[Int]])

  checkAll("Option", monoid.laws[Option[Int]])
  checkAll("Option", bindRec.laws[Option])
  checkAll("Option", monadPlus.strongLaws[Option])
  checkAll("Option", traverse.laws[Option])
  checkAll("Option", zip.laws[Option])
  checkAll("Option", isEmpty.laws[Option])
  checkAll("Option", cobind.laws[Option])
  checkAll("Option", align.laws[Option])

  checkAll("Option @@ First", monoid.laws[FirstOption[Int]])
  checkAll("Option @@ Last", monoid.laws[LastOption[Int]])
  checkAll("Option @@ Min", monoid.laws[MinOption[Int]])
  checkAll("Option @@ Max", monoid.laws[MaxOption[Int]])

  checkAll("Option @@ First", monad.laws[FirstOption])
  checkAll("Option @@ Last", monad.laws[LastOption])
  checkAll("Option @@ Min", monad.laws[MinOption])
  checkAll("Option @@ Max", monad.laws[MaxOption])

  "None is less than anything else" ! forAll { (x: Option[Int]) => Order[Option[Int]].greaterThanOrEqual(x, None) }

  "None is ignored in Option[A]@@Min" ! forAll { (x: Option[Int]) =>
    import syntax.monoid._
    (Min(x) |+| Min(None)) must_=== Min(x)
  }

  "None is ignored in Option[A]@@Max" ! forAll { (x: Option[Int]) =>
    import syntax.monoid._
    (Max(x) |+| Max(None)) must_=== Max(x)
  }

  object instances {
    def equal[A: Equal] = Equal[Option[A]]
    def order[A: Order] = Order[Option[A]]
    def semigroup[A: Semigroup] = Monoid[Option[A]]
    def bindRec[A] = BindRec[Option]
    def monad[A] = Monad[Option]

    def monoidFirst[A] = Monoid[Option[A] @@ First]
    def monoidLast[A] = Monoid[Option[A] @@ Last]

    // checking absence of ambiguity
    def equal[A: Order] = Equal[Option[A]]
  }
}