the description for this gist

post.scala

trait Language[Wrapper[_]] {
    type QueryObj
    case class Raw(q: QueryObj)
    case class WithFilter(q: QueryObj)
    case class WithPagination(q: QueryObj)

    def people(): Wrapper[Raw]
    // we could change plain Ints into our custom class, but will skip it for brevity
    def filterByIds(query: Wrapper[Raw], ids: Seq[Int]): Wrapper[WithFilter]
    def paginate(query: Wrapper[WithFilter], skip: Int, limit: Int): Wrapper[WithPagination]

    def run(query: Wrapper[WithPagination]): Wrapper[Seq[Person]]
  }