Scala example source code file (MonadState.scala)

This example Scala source code file (MonadState.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

monadstate

The MonadState.scala Scala example source code

package scalaz

////
/** The class of monads supporting the operations of
 * [[scalaz.State]].
 *
 */
////
trait MonadState[F[_], S] extends Monad[F] { self =>
  ////

  def state[A](a: A): F[A] = bind(init)(s => point(a))
  def constantState[A](a: A, s: => S): F[A] = bind(put(s))(_ => point(a))
  def init: F[S]
  def get: F[S]
  def gets[A](f: S => A): F[A] = bind(init)(s => point(f(s)))
  def put(s: S): F[Unit]
  def modify(f: S => S): F[Unit] = bind(init)(s => put(f(s)))

  ////

}

object MonadState {
  @inline def apply[F[_], S](implicit F: MonadState[F, S]): MonadState[F, S] = F

  ////

  ////
}