Scala example source code file (BitraverseTest.scala)

This example Scala source code file (BitraverseTest.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.

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Java - Scala tags/keywords

bitraverse, boolean, either, int, l_e_lo, left\-biased, list, option, r_e_ro, right\-biased, string, success, validation, vector

The BitraverseTest.scala Scala example source code

package scalaz

import scalaz.std.AllInstances.{tuple2Instance => _, _}
import scalaz.scalacheck.ScalazProperties._
import scalaz.scalacheck.ScalazArbitrary._

object BitraverseTest extends SpecLite {

  implicit val LE = Bitraverse[\/].leftTraverse[Int]
  implicit val RE = Bitraverse[\/].rightTraverse[Int]

  checkAll("Left-biased Bitraverse for Either",  traverse.laws[? \/ Int])
  checkAll("Right-biased Bitraverse for Either", traverse.laws[Int \/ ?])


  implicit val LT = Bitraverse[Tuple2].leftTraverse[Int]
  implicit val RT = Bitraverse[Tuple2].rightTraverse[Int]

  checkAll("Left-biased Bitraverse for (,)",  traverse.laws[(?, Int)])
  checkAll("Right-biased Bitraverse for (,)", traverse.laws[(Int, ?)])

  "bitraverseU" in {
    import syntax.bitraverse._
    val a: Validation[Int \/ String, Int \/ Boolean] = Success(\/-(true))
    val b = a.bitraverseU(identity, identity)
    val _ = b: (Int \/ Validation[String, Boolean])
    b must_=== \/-(Success(true))
  }

  "bisequenceU" in {
    import syntax.bitraverse._
    val a: Validation[Int \/ String, Int \/ Boolean] = Success(\/-(true))
    val b = a.bisequenceU
    val _ = b: (Int \/ Validation[String, Boolean])
    b must_=== \/-(Success(true))
  }

  "left/right bias" in {
    import scalaz.syntax.either._

    Bitraverse[\/].rightTraverse.traverse(42.left[Int])(x => Vector(x + 3)) must_===(Vector(-\/(42)))
    Bitraverse[\/].leftTraverse.traverse(42.left[Int])(x => Vector(x + 3))  must_===(Vector(-\/(45)))

    Bifoldable[\/].leftFoldable.foldMap(42.left[Int])(identity)  must_===(42)
    Bifoldable[\/].rightFoldable.foldMap(42.left[Int])(identity) must_===(0)
  }

  "both sides, left and right embedding" in {
    implicit val L_E_LO_RL: Traverse[λ[α => Option[α] \/ List[Int]]] = Bitraverse[\/].embed[Option,List].leftTraverse[Int]
    implicit val R_E_LO_RL: Traverse[λ[α => Option[Int] \/ List[α]]] = Bitraverse[\/].embed[Option,List].rightTraverse[Int]
    checkAll("Left-biased Bitraverse for Either[Option,List[_]]", traverse.laws[λ[α => Option[α] \/ List[Int]]])
    checkAll("Right-biased Bitraverse for Either[Option[_],List]", traverse.laws[λ[α => Option[Int] \/ List[α]]])

    implicit val L_E_LO = Bitraverse[\/].embedLeft[Option].leftTraverse[Int]
    implicit val R_E_RO = Bitraverse[\/].embedRight[Option].rightTraverse[Int]
    checkAll("Left-biased Bitraverse for Either[Option,_]", traverse.laws[λ[α => Option[α] \/ Int]])
    checkAll("Right-biased Bitraverse for Either[_,Option]", traverse.laws[λ[α => Int \/ Option[α]]])
  }

}

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