scalaz.ioeffect.Void.scala Maven / Gradle / Ivy

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package scalaz
package ioeffect

import scalaz.Leibniz.===
import scalaz.Liskov.<~<

trait VoidModule {

  trait Tag extends Any

  type Void <: Tag

  def absurd[A](v: Void): A

  def unsafeVoid: Void

  def isNothing: Void === Nothing

  def conforms[A]: Void <~< A
}

trait VoidFunctions {
  @inline final def absurd[A](v: Void): A = Void.absurd[A](v)
}

trait VoidSyntax {
  implicit class Ops(v: Void) {
    def absurd[A]: A = Void.absurd(v)
  }
}

// NOTE: this is some next level black compiler magic
// but without this object syntax doesn't resolve...
object VoidModule extends VoidSyntax {
  implicit def void_<~<[A]: Void <~< A = Void.conforms[A]
}

private[ioeffect] object VoidImpl extends VoidModule with VoidSyntax {
  type Void = Nothing

  def absurd[A](v: Void): A = v

  private[ioeffect] final class UnsafeVoid extends RuntimeException

  def unsafeVoid: Void = throw new UnsafeVoid

  def isNothing: Void === Nothing = Leibniz.refl[Void]

  def conforms[A]: Void <~< A = Liskov.refl[Void]

}