Semigroup.scala

trait Semigroup[A] {
  def append(a1: A, a2: A): A
}

sealed abstract class Validation[F: Semigroup] {
  final def and(other: Validation[F]) = (this, other) match {
    case (Failure(e1), Failure(e2)) => Failure(implicitly[Semigroup[F]].append(e1, e2))
    case (Failure(e1), Success()) => Failure(e1)
    case (Success(), Failure(e2)) => Failure(e2)
    case (Success(), Success()) => Success
  }
}

final case class Failure[F: Semigroup](e: F) extends Validation[F]

final case class Success[F: Semigroup]() extends Validation[F]