Is it true that an exception is always terminates the thread?

[Edward Z. Yang]

Excerpts from Heka Treep's message of Mon Jan 23 13:56:47 -0500 2012:
> adding the message queue (with Chan, MVar or STM) for each process will not
> help in this kind of imitation.

Why not? Instead of returning a thread ID, send the write end of a Chan
which the thread is waiting on.  You can send messages (normal or
errors) using it.

Edward