A short post on Concurrency

Right. So, I guess I am going the standard route to concurrency in a rewrite system and implement a 'par' primitive. I think it can be done without changes to the runtime.

'par f g' should do the following things:

1. Create a node for the results of evaluating the two arguments.
2. Start two threads which concurrently evaluate 'f nop' and 'g nop' which place their results in the node after being evaluated. Note, a dummy argument is necessary since otherwise both arguments would be fully reduced.
3. Block until the arguments are fully reduced.

Then there is exception handling. What to do if either thread returns an exception? There are two solutions.

1. The simplistic manner. Just place the exception thrown in the result node.
2. The right manner. As soon as either thread throws an exception, stop the other thread, and throw that exception upward.

There are no users, I expect no users, I'll do the simplistic manner.