SafeBool

Boolean isomorphism.

Mix into the base type and override this.companion there.

Examples:

sealed trait Enabled extends SafeBool[Enabled] {
  override final def companion = Enabled
}

case object Enabled extends Enabled with SafeBool.Object[Enabled] {
  override def positive = Enabled
  override def negative = Disabled
}

case object Disabled extends Enabled

sealed abstract class Permission extends SafeBool.WithBoolOps[Permission] {
  override final def companion = Permission
}

case object Allow extends Permission
case object Deny extends Permission

object Permission extends SafeBool.Object[Permission] {
  override def positive = Allow
  override def negative = Deny
}