Scala example source code file (Bias.scala)

This example Scala source code file (Bias.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

bifoldable, bifunctor, bitraverse, foldable

The Bias.scala Scala example source code

package scalaz

private trait LeftFunctor[F[_,_], X] extends Functor[F[?, X]] {
  implicit def F: Bifunctor[F]

  override def map[A, C](fax: F[A, X])(f: A => C): F[C, X] =
    F.bimap(fax)(f, identity)
}

private trait RightFunctor[F[_,_], X] extends Functor[F[X, ?]] {
  implicit def F: Bifunctor[F]

  override def map[A, C](fax: F[X, A])(f: A => C): F[X, C] =
    F.bimap(fax)(identity, f)
}

private trait UFunctor[F[_,_]] extends Functor[λ[α => F[α, α]]] {
  implicit def F: Bifunctor[F]

  override def map[A, C](fax: F[A, A])(f: A => C): F[C, C] =
    F.bimap(fax)(f, f)
}

private trait LeftFoldable[F[_,_], X] extends Foldable[F[?, X]] {
  implicit def F: Bifoldable[F]

  override def foldMap[A,B](fa: F[A, X])(f: A => B)(implicit B: Monoid[B]): B =
    F.bifoldMap(fa)(f)(Function const B.zero)

  override def foldRight[A, B](fa: F[A, X], z: => B)(f: (A, => B) => B): B =
    F.bifoldRight(fa, z)(f)((_, b) => b)

  override def foldLeft[A, B](fa: F[A, X], z: B)(f: (B, A) => B): B =
    F.bifoldLeft(fa, z)(f)((b, _) => b)
}

private trait RightFoldable[F[_,_], X] extends Foldable[F[X, ?]] {
  implicit def F: Bifoldable[F]

  override def foldMap[A,B](fa: F[X, A])(f: A => B)(implicit B: Monoid[B]): B =
    F.bifoldMap(fa)(Function const B.zero)(f)

  override def foldRight[A, B](fa: F[X, A], z: => B)(f: (A, => B) => B): B =
    F.bifoldRight(fa, z)((_, b) => b)(f)

  override def foldLeft[A, B](fa: F[X, A], z: B)(f: (B, A) => B): B =
    F.bifoldLeft(fa, z)((b, _) => b)(f)
}

private trait UFoldable[F[_,_]] extends Foldable[λ[α => F[α, α]]] {
  implicit def F: Bifoldable[F]

  override def foldMap[A,B](fa: F[A, A])(f: A => B)(implicit B: Monoid[B]): B =
    F.bifoldMap(fa)(f)(f)

  override def foldRight[A, B](fa: F[A, A], z: => B)(f: (A, => B) => B): B =
    F.bifoldRight(fa, z)(f)(f)

  override def foldLeft[A, B](fa: F[A, A], z: B)(f: (B, A) => B): B =
    F.bifoldLeft(fa, z)(f)(f)
}

private trait LeftTraverse[F[_,_], X] extends Traverse[F[?, X]]
    with LeftFunctor[F, X] with LeftFoldable[F, X] {
  implicit def F: Bitraverse[F]

  def traverseImpl[G[_]:Applicative,A,B](fa: F[A, X])(f: A => G[B]): G[F[B, X]] =
    F.bitraverseImpl(fa)(f, x => Applicative[G] point x)
}

private trait RightTraverse[F[_,_], X] extends Traverse[F[X, ?]]
    with RightFunctor[F, X] with RightFoldable[F, X] {
  implicit def F: Bitraverse[F]

  def traverseImpl[G[_]:Applicative,A,B](fa: F[X, A])(f: A => G[B]): G[F[X, B]] =
    F.bitraverseImpl(fa)(x => Applicative[G] point x, f)
}

private trait UTraverse[F[_,_]] extends Traverse[λ[α => F[α, α]]]
    with UFunctor[F] with UFoldable[F] {
  implicit def F: Bitraverse[F]

  def traverseImpl[G[_]:Applicative,A,B](fa: F[A, A])(f: A => G[B]): G[F[B, B]] =
    F.bitraverseImpl(fa)(f, f)
}