Applicative with map2

ex.scala

trait Applicative[F[_]] extends Functor[F] {
  def pure[A](x: A): F[A]
  def ap[A, B](ff: F[A => B])(fa: F[A]): F[B]  
  def map2[A, B, Z](fa: F[A], fb: F[B])(f: (A, B) => Z): F[Z] =
      ap(map(fa)(a => (b: B) => f(a,b)))(fb)
}