applicativeMap2.scala

trait Applicative[F[_]] {
  def ap[A, B](ff: F[A => B])(fa: F[A]): F[B]

  def pure[A](x: A): F[A]

  def map2[A, B, C](fa: F[A], fb: F[B])(f: (A, B) => C): F[C] = {
    val fCurried: A => B => C = f.curried
    val fbc: F[B => C]  = ap[A, (B => C)](pure(fCurried))(fa)
    ap[B, C](fbc)(fb)
  }
}