Scala example source code file (Comonad.scala)

This example Scala source code file (Comonad.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

boolean, cobindlaws, comonad, comonadlaws, equal

The Comonad.scala Scala example source code

package scalaz

////
/**
 *
 */
////
trait Comonad[F[_]] extends Cobind[F] { self =>
  ////
  /** Also known as `extract` / `copure` */
  def copoint[A](p: F[A]): A

  // derived functions

  /** alias for `copoint` */
  final def copure[A](p: F[A]): A = copoint(p)

  trait ComonadLaws extends CobindLaws {
    def cobindLeftIdentity[A](fa: F[A])(implicit F: Equal[F[A]]): Boolean =
      F.equal(cobind(fa)(copoint), fa)
    def cobindRightIdentity[A, B](fa: F[A], f: F[A] => B)(implicit F: Equal[B]): Boolean =
      F.equal(copoint(cobind(fa)(f)), f(fa))
  }

  def comonadLaw = new ComonadLaws {}

  ////
  val comonadSyntax = new scalaz.syntax.ComonadSyntax[F] { def F = Comonad.this }
}

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

  ////

  ////
}