Invalid definition

Invalid.scala

  trait SequenceValidation[A, B] {
    self =>
    def apply(seq: Seq[A]): DomainValidation[Seq[B]]

    def map[C](f: B => C) = new SequenceValidation[A, C] {
      def apply(seq: Seq[A]): DomainValidation[Seq[C]] =
        self.apply(seq) map { validSequence => validSequence map f }
    }

    def flatMap[C](f: B => SequenceValidation[A, C]) = new SequenceValidation[A, C] {
      def apply(seq: Seq[A]): DomainValidation[Seq[C]] = {
         val result: DomainValidation[Seq[DomainValidation[Seq[C]]]] = self.apply(seq) map  { validSequence =>
           validSequence map  { item =>
             f(item)(seq)
           }
        }

        result.flatMap { s =>
          s.sequence map { sp => sp.flatten}
        }
      }
    }
  }