What does interruptibility mean exactly?

[Don Stewart]

v.dijk.bas:
> Hello,
> 
> I've a short question about interruptible operations. In the following
> program is it possible for 'putMVar' to re-throw asynchronous
> exceptions even when asynchronous exception are blocked/masked?
> 
>   newEmptyMVar >>= \mv -> block $ putMVar mv x
> 
> The documentation in Control.Exception about interruptible
> operations[1] confused me:
> 
> "Some operations are interruptible, which means that they can receive
> asynchronous exceptions even in the scope of a block. Any function
> which may itself block is defined as interruptible..."
> 

I think the best definition of interruptible is in this paper:

    www.haskell.org/~simonmar/papers/async.pdf

Section 5.3