ValidatorTypeClass.scala

sealed trait ValidatorTypeClass[A] {
  def validate(a: A): Boolean
}
object ValidatorTypeClass {
  def validateElement[A](a: A)(implicit v: ValidatorTypeClass[A]) = v.validate(a)

  implicit def stringElementValidator = new ValidatorTypeClass[String] {
    override def validate(a: String): Boolean = ??? //validation logic for strings
  }
  implicit def numberElementValidator = new ValidatorTypeClass[Double] {
    override def validate(a: Double): Boolean = ??? //validation logic for numbers
  }
  implicit def booleanElementValidator = new ValidatorTypeClass[Boolean] {
    override def validate(a: Boolean): Boolean = ??? //validation logic for booleans
  }
  implicit def complexElementValidator = new ValidatorTypeClass[ComplexElement] {
    override def validate(a: ComplexElement): Boolean = a.value.forall(validateElement)
  }
}

import ValidatorTypeClass._
val complex = ComplexElement(
  value = List(
    StringElement(value = "first element"),
    StringElement(value = "second element")
  )
)
validateElement(complex)