22.10. Transforming Nested Control Contexts

The CPS transformation is more complex when it has to deal with calls to transformed functions. To see this, let us look at turning a recursive visit into an iteration, like in Section 22.7, “Turning a Recursive Visit into an Iteration,” on page 326. For simplicity, we will visit a linked list, not a tree:

def visit(a: List[String]): String @cps[String] = {
  if (a.isEmpty) "" else {
    shift {
      k: (Unit => String) => {
        cont = k
        a.head
      }
    }
    visit(a.tail)
  }
}