A shapeless Predicate?

gistfile1.txt

import shapeless._
import Poly._
import TypeOperators._

trait PredF extends (Id ~>> Boolean){
  self =>

  def apply[T](arg: T): Boolean

  def or(that: Id ~>> Boolean) = new PredF{
    def apply[T](arg: T) = self(arg) || that(arg)
  }
  def and(that: Id ~>> Boolean) = new PredF{
    def apply[T](arg: T) = self(arg) && that(arg)
  }
  def xor(that: Id ~>> Boolean) = new PredF{
    def apply[T](arg: T) = if(self(arg)) !that(arg) else that(arg)
  }
}

//Dunno if this'll work...
object NotF{
  def apply(that: Id ~>> Boolean) = !that(_)
}