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Scala example source code file (PartialFunction.scala)

This example Scala source code file (PartialFunction.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

arrow, boolean, category, choice, partialfunction, partialfunctioninstances

The PartialFunction.scala Scala example source code

package scalaz
package std

trait PartialFunctionInstances {
  implicit val partialFunctionInstance = new Arrow[PartialFunction] with Category[PartialFunction] with Choice[PartialFunction] {
    def arr[A, B](f: A => B) = {
      case a => f(a)
    def compose[A, B, C](f: PartialFunction[B, C], g: PartialFunction[A, B]) = new PartialFunction[A, C] {
      def apply(a: A): C = f(g(a))
      def isDefinedAt(a: A): Boolean = g.isDefinedAt(a) && f.isDefinedAt(g(a))

    def id[A] = {
      case a => a

    def choice[A, B, C](f: => PartialFunction[A, C], g: => PartialFunction[B, C]): PartialFunction[A \/ B, C] = {
      case -\/(a) if f isDefinedAt a => f(a)
      case \/-(b) if g isDefinedAt b => g(b)

    override def split[A, B, C, D](f: PartialFunction[A, B], g: PartialFunction[C, D]): PartialFunction[(A,  C), (B, D)] = {
      case (a, c) if f.isDefinedAt(a) && g.isDefinedAt(c) => (f(a), g(c))

    def first[A, B, C](f: PartialFunction[A, B]): PartialFunction[(A, C), (B, C)] = {
      case (a, c) if f.isDefinedAt(a) => (f(a), c)

object partialFunction extends PartialFunctionInstances

Other Scala examples (source code examples)

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