Scala example source code file (IoExceptionOr.scala)

This example Scala source code file (IoExceptionOr.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, ioexception, ioexceptionor, none, option, some

The IoExceptionOr.scala Scala example source code

package scalaz
package effect

sealed abstract class IoExceptionOr[A] {

  import IoExceptionOr._

  def fold[X](ioException: IoException => X, or: A => X): X

  def map[B](f: A => B): IoExceptionOr[B] =
    fold(ioException, a => IoExceptionOr(f(a)))

  def flatMap[B](f: A => IoExceptionOr[B]): IoExceptionOr[B] =
    fold(ioException, f)

  def forall(p: A => Boolean): Boolean =
    fold(_ => true, p)

  def exists(p: A => Boolean): Boolean =
    fold(_ => false, p)

  def toOption: Option[A] =
    fold(_ => None, Some(_))

  def valueOr(a: => A): A =
    fold(_ => a, x => x)
}

object IoExceptionOr {
  def apply[A](a: => A): IoExceptionOr[A] =
    try {
      ioExceptionOr(a)
    } catch {
      case e: java.io.IOException => ioException(e)
    }
  def unapply[A](ioExceptionOr: IoExceptionOr[A]) = ioExceptionOr.toOption

  type IoException =
  java.io.IOException

  def ioException[A]: IoException => IoExceptionOr[A] =
    e => new IoExceptionOr[A] {
      def fold[X](ioException: IoException => X, or: A => X) =
        ioException(e)
    }

  def ioExceptionOr[A](a: A): IoExceptionOr[A] = new IoExceptionOr[A] {
    def fold[X](ioException: IoException => X, or: A => X) =
      or(a)
  }

}