Scala example source code file (IdOps.scala)

This example Scala source code file (IdOps.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

anyval, applicative, boolean, idops, monoid, none, null, partialfunction, some, toidops

The IdOps.scala Scala example source code

package scalaz
package syntax

import annotation.tailrec

final class IdOps[A](val self: A) extends AnyVal {
  /**Returns `self` if it is non-null, otherwise returns `d`. */
  final def ??(d: => A)(implicit ev: Null <:< A): A =
    if (self == null) d else self

  /**Applies `self` to the provided function. The Thrush combinator. */
  final def |>[B](f: A => B): B =
    f(self)

  /**Applies `self` to the provided function. The Thrush combinator. */
  final def ▹[B](f: A => B): B =
    f(self)

  final def squared: (A, A) =
    (self, self)

  /**
   * @return the result of pf(value) if defined, otherwise the the Zero element of type B.
   */
  def matchOrZero[B: Monoid](pf: PartialFunction[A, B]): B =
    pf.lift(self) match {
      case None    => Monoid[B].zero
      case Some(x) => x
    }

  /** Repeatedly apply `f`, seeded with `self`, checking after each iteration whether the predicate `p` holds. */
  final def doWhile(f: A => A, p: A => Boolean): A = {
    @tailrec
    def loop(value: A): A = {
      val x = f(value)
      if (p(x)) loop(x) else x
    }
    loop(self)
  }

  /** Repeatedly apply `f`, seeded with `self`, checking before each iteration whether the predicate `p` holds. */
  final def whileDo(f: A => A, p: A => Boolean): A = {
    @tailrec
    def loop(value: A): A = {
      if (p(value)) loop(f(value)) else value
    }
    loop(self)
  }

  /**
   * If the provided partial function is defined for `self` run this,
   * otherwise lift `self` into `F` with the provided [[scalaz.Applicative]].
   */
  def visit[F[_] : Applicative](p: PartialFunction[A, F[A]]): F[A] =
    if (p isDefinedAt self) p(self)
    else Applicative[F].point(self)
}

trait ToIdOps {
  implicit def ToIdOps[A](a: A): IdOps[A] = new IdOps(a)
}