Simple validation thing

Validate.scala

sealed abstract class Validation[T] {
  def must(p: (T => Boolean), error: String): Validation[T]
}

object Validation {
  def apply[T](value: T): Validation[T] = Valid(value)
}

case class Invalid[T](value: T, errors: List[String]) extends Validation[T] {
  def must(p: (T => Boolean), error: String): Validation[T] =
    if (p(value)) this
    else Invalid(value, error +: errors)
}
case class Valid[T](value: T) extends Validation[T] {
  def must(p: (T => Boolean), error: String): Validation[T] =
    if (p(value)) this
    else Invalid(value, List(error))
}

object Test extends App {
  Validate("Hello").must( (_.length > 0), "No empty strings, please")
                   .must( (_ contains "ring"), "If you liked it you should have put a ring in it")
}