MaybeRef

MaybeRef.scala

object MaybeRef {
  sealed abstract class Optional

  implicit class MaybeRefFunctions[A](val dis: MaybeRef[A]) extends AnyVal {
    def map[B](f: A => B): MaybeRef[B] = {
      if (dis == null) {
        null
      } else { 
        Tag(f(Tag.unwrap(dis)))
      }
    }

    def get(default: A): A = if (dis == null) default else Tag.unwrap(dis)
    def notEmpty: Boolean = dis != null
    def isEmpty: Boolean = dis == null
  }
}

trait MaybeRefSyntax {
  import MaybeRef._

  def just[A](a: A): MaybeRef[A] = Tag(a)
  def nothing[A]: MaybeRef[A] = null
}

type MaybeRef[A] = A @@ MaybeRef.Optional