Perhaps we should bite the bullet and have non-interruptible versions of some of the blocking operations, including throwTo. I would certainly appreciate this! There is a long-standing bug (or at least misfeature) in my events code which means you can't send asynchronous exceptions to

Simon M wrote (snipped) threads which use it, because of the difficulty of doing takeMVar/putMVar under these conditions. It would be possible to avoid this currently by putting in several calls to block and unblock to make sure that MVars which are supposed to be normally full really are normally full, but this is apparently costly.