black hole detection and concurrency

Ian Lynagh igloo at
Mon Jan 5 09:29:40 EST 2009

On Mon, Dec 29, 2008 at 05:07:22PM +0100, Bertram Felgenhauer wrote:
> Simon Peyton-Jones wrote:
> > 
> > This is odd (to me).  The "permanently bound" stuff applies only to
> > *synchronous* exceptions, which thread-killing is not.  Simon M will
> > have more to say when he gets back
> This is true when the exception is raised the first time. However, some
> exception handling functions like 'bracket' catch the exception, do
> their cleanup, and then throw the exception again. This is done in
> onException, and goes through throwIO and eventually raiseIO#. At this
> point the originally asynchronous exception has become a synchronous
> one.

We don't currently have a way to know whether an exception was thrown
asynchronously or not, right?

Should we actually be throwing
    data SomeExceptionSync = SomeExceptionSync Bool -- synchronous? 
with catch etc ignoring the Bool, but bracket etc handling it


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