  Functional coroutines are a restricted form of control mechanism, where each
coroutine is represented with both a continuation and an environment. This
restriction was originally obtained by considering a constructive version of
Parigot's classical natural deduction which is sound and complete for the
Constant Domain logic. In this article, we present a refinement of de Groote's
abstract machine for functional coroutines and we prove its correctness.
Therefore, this abstract machine also provides a direct computational
interpretation of the Constant Domain logic.
