> it's better to avoid shared mutable state entirely.

Yes! I would even go so far as to have the type system separate the mutable from the non-mutable for this reason!

> Something actor like fits better and C# or Go channels works wonders.

Or even STM channels/queues:

  https://hackage.haskell.org/package/stm/docs/Control-Concurrent-STM-TChan.html
  https://hackage.haskell.org/package/stm/docs/Control-Concurrent-STM-TQueue.html