gistfile1.scala

  def validateProduct(product: Product): List[String] =
    requiredFieldsArePresent(product) |+|
      idHasPermittedLength(product) |+|
      nameHasPermittedLength(product) |+|
      rateTypeIsCPM(product) |+|
      productIdIsUnique(product /*, mongoDao*/) |+|
      productNameIsUnique(product /*, mongoDao*/) |+|
      currencyIsISOCompliant(product) match {
      case Failure(errors) => errors.toList
      case _ => Nil
    }

gistfile2.scala

  implicit object ProductSemigroup extends Semigroup[Product] {
    override def append(f1: Product, f2: => Product): Product = f1
  }