Implementation of IsHListOfM object

IsHListOfM.scala

object IsHListOfM {
  def apply[M[_], In <: HList, Out <: HList](implicit isHM: IsHListOfM[M, In, Out], m: Monad[M]): IsHListOfM[M, In, Out] = isHM

  implicit def IsHNilHListOfM[M[_]](implicit m: Monad[M]) = new IsHListOfM[M, HNil, HNil] {
    override def hsequence(l: HNil): M[HNil] = m.pure(HNil)
  }

  implicit def hconsIsHListOfM[M[_], H, In <: HList, Out <: HList](implicit ev: IsHListOfM[M, In, Out], m: Monad[M]): IsHListOfM[M, M[H] :: In, H :: Out] = new IsHListOfM[M, M[H] :: In, H :: Out] {
    override def hsequence(l: M[H] :: In): M[H :: Out] =
      l.head.flatMap(h => ev.hsequence(l.tail).map(h :: _))
  }
}