BodyParserModule.scala

trait JsonParser extends BodyParserModule {
  def parse[String, O <: Parsable[O]](a: String): O = a match {
    case O(o) => o
    case _ => ???
  }
}


sealed trait Parsable[A] {
  def parse(a: String): A
  def unapply(a: String): A
}

case class AbvCalc(fg: Double, og: Double) extends Parsable[AbvCalc] {
  def parse(a: String): AbvCalc = ???
  def unapply(a: String): Option[AbvCalc] = ???
}