Avoiding BlockedIndefinitelyOnSTM exceptions

[Brandon Simmons]

> I have what may sound like an unusual request: I would like to
> automatically avoid `BlockedIndefinitelyOnSTM` exceptions with a
> primitive that looks something like this:

Have you seen ezyang's post here? Lots of hairy details that are
probably relevant

    http://blog.ezyang.com/2011/07/blockedindefinitelyonmvar/

Brandon