predicate boolean algebra

PredicateBooleanAlgebra.scala

import spire.algebra._
import spire.implicits._

object Main {
  def main(args: Array[String]): Unit = {
    implicit def PredicateBooleanAlgebra[T] = new Bool[T => Boolean] {
      def one: T => Boolean = _ => true
      def zero: T => Boolean = _ => false
      def and(a: T => Boolean, b: T => Boolean): T => Boolean = x => a(x) && b(x)
      def or(a: T => Boolean, b: T => Boolean): T => Boolean = x => a(x) || b(x)
      def complement(a: T => Boolean) = x => !a(x)
    }

    def c[T](t: T)(s: Set[T]) = s contains t

    val s = Set(1, 2, 3).subsets.map(_.toSet).toSet
    println(s.filter(~(c(1) _) & (c(2) _)))
  }
}