ShapelessValidatorFieldType.scala

import jto.validation.{Rule, VA}
import shapeless.Poly1
import shapeless._
import labelled.{FieldType, field}


object validator extends Poly1 {
  implicit def list[H <: Validator[Int], T <: HList](implicit witness: Witness.Aux[H]) : Case.Aux[FieldType[H, String]::T, HList]  = at(l =>   validator(l.head) :: HNil )

  implicit def kvString[K <: Validator[String]](implicit witness: Witness.Aux[K]): Case.Aux[FieldType[K, String], VA[String]] = at(in => {
    getValidatorByType(in).rules.validate(getFieldValue(in))
  })
  implicit def kvInt[K <: Validator[Int]](implicit witness: Witness.Aux[K]): Case.Aux[FieldType[K, String], VA[Int]] = at(in => {
    getValidatorByType(in).rules.validate(getFieldValue(in))
  })
  implicit def kvBoolean[K <: Validator[Boolean]](implicit witness: Witness.Aux[K]): Case.Aux[FieldType[K, String], VA[Boolean]] = at(in => {
    getValidatorByType(in).rules.validate(getFieldValue(in))
  })
}
trait Validator[In] {
  def rules: Rule[String, In]
}
object EmailValidator extends Validator[String] {
  val rules: Rule[String, String] = Rules.email |+| Rules.notEmpty
}
object IntValidator extends Validator[Int] {
  val rules: Rule[String, Int] = Rules.intR
}
object BoolValidator extends Validator[Boolean] {
  val rules: Rule[String, Boolean] = Rules.booleanR
}

type Email = FieldType[EmailValidator.type, String]
def email(value: String): FieldType[EmailValidator.type, String] = field[EmailValidator.type](value)
type IntString = FieldType[IntValidator.type, String]
def intString(value: String): FieldType[IntValidator.type, String] = field[IntValidator.type](value)
type BoolString = FieldType[BoolValidator.type, String]
def boolString(value: String): FieldType[BoolValidator.type, String] = field[BoolValidator.type](value)
def getValidatorByType[K](value: FieldType[K, String])(implicit witness: Witness.Aux[K]): K = witness.value
def getFieldValue[K](value: FieldType[K, String]): String = value


case class Row(email: Email, age: IntString, cgu: BoolString)
validator(intString("a") ::  intString("1") :: HNil)