gistfile1.scala

object Foo {

  def given[A,B,C,S](aa: S => Stream[A], 
                     bb: S => Stream[B], 
                     cc: S => Stream[C]) = new {
    def thereExists(f: (A,B,C)=>Boolean)(s: S): Boolean = {
      val cross = for {
        a <- aa(s)
        b <- bb(s)
        c <- cc(s)
      } yield f(a,b,c)
      cross.exists(identity)
    }
  }

  import scalaz.syntax.applicative._
  import scalaz.std.stream._
  import scalaz.syntax.foldable._
  import scalaz.Tags.Disjunction
  
  def given[A,B,C,D,S](aa: S => Stream[A], 
                       bb: S => Stream[B], 
                       cc: S => Stream[C], 
                       dd: S => Stream[D]) = new {
    def thereExists(f: (A,B,C,D)=>Boolean)(s: S): Boolean = 
      ^^^(aa(s),bb(s),cc(s),dd(s))(f).foldMap(Disjunction)// lift f to Stream
    
  }

}