Draft for hs-style function-in-applicative usage

gistfile1.scala

import scalaz._
import Scalaz._

trait AMA[M[_], A] extends PimpedType[M[A]] {
  //just <*> with a swapped arguments
  def <@>[X, Y](x: M[X])(implicit ev: A <:< (X=>Y), app: Apply[M], f: Functor[M]): M[Y] = app.apply(value map ev, x)
}

object Fs {
  implicit def ValidationAMA[A, E](v: Validation[E, A]) = new AMA[({type l[α]=Validation[E, α]})#l, A] {
    val value = v
  }
}

class AppDemo {
  import Fs._

  def main(args: Array[String]) {
    println(
      {(a: Int) => (b: Int) => a+b}.successNel[String] <@> 1.successNel[String] <@> 2.successNel[String]
    )

    println(
      {(a: Int) => (b: Int) => a+b}.successNel[String] <@> "Opps".failNel[Int] <@> "That's wrong".failNel[Int]
    )
  }
}