Toyvo: I wasn’t sure how to implement the deferred message feature. Scala uses a PartialFunction class, which I don’t think has any equivalent in Haskell, and I couldn’t see a clean way to implement it. I’m not sure how Erlang does this. So, for simplicity, I left it out for now.

I probably could use a Chan instead of a TChan. I’m not sure of the reasons for choosing one over the other.

There are just this practical feature I miss here (or maybe just don’t see): the ability to defer messages. You can find it in both Erlang and Scala receive constructs – if none of the following patterns match, the message is deferred to be processed later.

However you seem to do a simple pop.

In addition, IMHO ‘pop’ and ‘push’ are a little confusing as in many languages they refer to a LIFO stack, while you are using a FIFO channel.

Finally, why do you need atomic access guaranteed by STM and TChan here? Would a Chan suffice? I think Chan is ok with many writer threads and a reader thread.

Will be glad to read more of your code. Consider posting to http://hpaste.org – it highlights your syntax.