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Scala example source code file (IsEmpty.scala)

This example Scala source code file (IsEmpty.scala) is included in the "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

boolean, isempty, isemptylaw, plusempty

The IsEmpty.scala Scala example source code

package scalaz

 * Typeclass that permits testing whether some type with an empty representation
 * is in fact empty.
trait IsEmpty[F[_]] extends PlusEmpty[F] { self =>
  def isEmpty[A](fa: F[A]): Boolean

  // derived functions

  trait IsEmptyLaw extends EmptyLaw {
    def emptyIsEmpty[A]: Boolean = isEmpty(empty[A])

    def emptyPlusIdentity[A](f1: F[A], f2: F[A]): Boolean =
      (isEmpty(f1) && isEmpty(f2)) == isEmpty(plus(f1, f2))

  def isEmptyLaw = new IsEmptyLaw {}

  val isEmptySyntax = new scalaz.syntax.IsEmptySyntax[F] { def F = IsEmpty.this }

object IsEmpty {
  @inline def apply[F[_]](implicit F: IsEmpty[F]): IsEmpty[F] = F



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