Use SomeException for the type, as it is the base of the exception hierarchy.
But it is usually recommended that you *don't* do this, as it even captures Ctrl-c invocations:
I think there are situation when it is justified to catch almost all exceptions. And people do that a lot, which often leads to ctrl-c not properly working (e.g. we had this in HUnit before 1.2.4.2). The way I deal with this is: someAction `catches` [ -- Re-throw AsyncException, otherwise execution will not terminate -- on SIGINT (ctrl-c). All AsyncExceptions are re-thrown (not -- just UserInterrupt) because all of them indicate severe -- conditions and should not occur during normal operation. Handler (\e -> throw (e :: AsyncException)), Handler (\e -> yourHandler $ e :: SomeException) ] Cheers, Simon