learninCats-Parallel

gistfile1.txt

object ParEitherNonEmpty {
  import cats.data.NonEmptyList.catsDataSemigroupForNonEmptyList
  import cats.data.{NonEmptyList, Validated}

  new Parallel[Either[NonEmptyList[_], ?]] {
    override type F[v] = Validated[NonEmptyList[_], v]
    override def applicative: Applicative[Validated[NonEmptyList[_], *]] = {
      Validated.catsDataApplicativeErrorForValidated[NonEmptyList[_]](catsDataSemigroupForNonEmptyList)
    }

    override def monad: Monad[Either[NonEmptyList[_], ?]] = cats.instances.either.catsStdInstancesForEither

    override def sequential: ~>[F, Either[NonEmptyList[_], ?]] = new FunctionK[F, Either[NonEmptyList[_], ?]]{
      override def apply[A](fa: Validated[NonEmptyList[_], A]): Either[NonEmptyList[_], A] = fa match {
        case Validated.Valid(a) => Right(a)
        case Validated.Invalid(e) => Left(e)
      }
    }

    override def parallel: ~>[Either[NonEmptyList[_], ?], F] = new ~>[Either[NonEmptyList[_], ?], F] {
      override def apply[A](fa: Either[NonEmptyList[_], A]): F[A] = fa match {
        case Right(value) => Validated.valid(value)
        case Left(err) => Validated.invalid(err)
      }
    }
  }
}