DeltaStuff.scala

trait Delta[U, A] {
  def apply(a: A): DeltaIO[U, A]
}

sealed trait DeltaIOA[U, A]
case class GetGuid[U]() extends DeltaIOA[U, Guid]
//case class GetId[U, T <: U]() extends DeltaIOA[U, Id[T]]
case class GetContext[U]() extends DeltaIOA[U, DeltaIOContext]
case class GetDeltaId[U]() extends DeltaIOA[U, DeltaId]
case class GetPRInt[U]() extends DeltaIOA[U, Int]
case class GetPRIntUntil[U](bound: Int) extends DeltaIOA[U, Int]
case class GetPRLong[U]() extends DeltaIOA[U, Long]
case class GetPRBoolean[U]() extends DeltaIOA[U, Boolean]
case class GetPRFloat[U]() extends DeltaIOA[U, Float]
case class GetPRDouble[U]() extends DeltaIOA[U, Double]
case class Put[U, T <: U](create: Id[T] => DeltaIO[U, T]) extends DeltaIOA[U, T]

type DeltaIO[U, A] = Free[({ type T[X] = DeltaIOA[U, X] })#T, A]