[QuickCheck] Detecting UserInterrupt / getting uncaught exceptions

[Simon Hengel]

Hi,
when the user presses ctrl-c I want to abort test runs.  I think
currently the only way to achieve this is to check the failure reason,
something like:

    isUserInterrupt :: Result -> Bool
    isUserInterrupt r = case r of
      Failure {reason = "Exception: 'user interrupt'"} -> True
      _ -> False

For my use cases it would be convenient if QuickCheck would not catch
(or re-throw) UserInterrupt (or preferably any AsyncException).  This
way they would hit 'main' and the program would terminate as expected.

Somewhat related, it would be useful if I could get the exception value
when a property fails due to an uncaught exception, so that I can e.g.
print the exception type.  The issue that I see here is that this would
either make the API conditional, or it would tie QuickCheck to
"Control.Exception".  Not sure if this is an option.  Any thoughts?

Cheers,
Simon