Add comments to scheduler.hpp and stack.hpp

rt/include/typon/scheduler.hpp

 #ifndef TYPON_SCHEDULER_HPP_INCLUDED
 #define TYPON_SCHEDULER_HPP_INCLUDED
 
+/* Continuation-stealing scheduler */
+
+/* Papers:
+
+   .  N. S. Arora, R. D. Blumofe, and C. G. Plaxton. 1998.
+      Thread scheduling for multiprogrammed multiprocessors.
+      https://doi.org/10.1145/277651.277678
+
+   .  C. X. Lin, T .W Huang, and M. D. F. Wong. 2020.
+      An efficient work-stealing scheduler for task dependency graph.
+      https://tsung-wei-huang.github.io/papers/icpads20.pdf
+
+   .  F. Schmaus, N. Pfeiffer, W. Schröder-Preikschat, T. Hönig, and J. Nolte.
+      2021. Nowa: a wait-free continuation-stealing concurrency platform.
+      https://www4.cs.fau.de/Publications/2021/schmaus2021nowa.pdf
+*/
+
+
 #include <atomic>
 #include <bit>
 #include <coroutine>

rt/include/typon/stack.hpp

 #ifndef TYPON_FUNDAMENTAL_STACK_HPP_INCLUDED
 #define TYPON_FUNDAMENTAL_STACK_HPP_INCLUDED
 
+/* Work-stealing deque */
+
+/* A stack of continuations that may be stolen and resumed concurrently.
+   Continuations are pushed when a potentially concurrent child task is
+   started and popped when the child completes, unless stolen first by a
+   concurrent worker. Thieves steal from the oldest continuations first,
+   while completed children tasks try to resume the most recent.
+
+   Furthermore, the whole stack may be suspended while waiting for an
+   asynchronous operation. In that case thieves may still steal but the
+   most recent child task is suspended. Suspended stacks will be enabled
+   when the asynchronous operation completes, at which point a thief may
+   take over the whole stack and resume the suspended child task.
+
+   There are five possible states:
+   - ACTIVE: A worker is actively running a child task.
+   - WAITING: Waiting on an asynchronous operation.
+   - EMPTY: Like WAITING, but no continuation remains unstolen.
+   - READY: A thief may take the whole stack and resume the suspended task.
+   - DONE: No more task remains, suspended or otherwise.
+
+   Papers:
+
+   .  D. Chase and Y. Lev. 2005.
+      Dynamic circular work-stealing deque.
+      https://doi.org/10.1145/1073970.1073974
+
+   .  N. M. Lê, A. Pop, A. Cohen, and F. Zappa Nardelli. 2013.
+      Correct and efficient work-stealing for weak memory models.
+      https://doi.org/10.1145/2517327.2442524
+
+   .  Kyle Singer, Yifan Xu, and I-Ting Angelina Lee. 2019.
+      Proactive work stealing for futures.
+      https://doi.org/10.1145/3293883.3295735
+*/
+
+
 #include <atomic>
 #include <cstdint>
 #include <memory>