apply.scala

package scalaz
package tc

import scala.language.experimental.macros

@meta.minimal("ap", "zip")
trait ApplyClass[F[_]] extends FunctorClass[F] {
  def ap[A, B](fa: F[A])(f: F[A => B]): F[B] = map(zip(f, fa)) { case (f, a) => f(a) }

  def apply2[A, B, C](fa: => F[A], fb: => F[B])(f: (A, B) => C): F[C] =
    ap(fb)(map(fa)(f.curried))

  def zip[A, B](fa: F[A], fb: F[B]): F[(A, B)] = ap(fa)(map(fb)(b => a => (a, b)))
}

trait ApplySyntax {
  implicit final class ToApplyOps[F[_], A](fa: F[A]) {
    def ap[B](f: F[A => B])(implicit ev: Apply[F]): F[B] =
      macro ops.Ops.i_1

    def liftA2[B, C](fb: F[B])(f: (A, B) => C)(implicit ev: Apply[F]): F[C] =
      fb.ap(Apply[F].map(fa)(a => f(a, _)))
  }
}