-catch handles the passing around of the state in the IO monad; if we
-don't actually apply (and hence run) an IO computation, we don't get
-any exceptions! Hence a large mantrap to watch out for is
+catchException used to handle the passing around of the state to the
+action and the handler. This turned out to be a bad idea - it meant
+that we had to wrap both arguments in thunks so they could be entered
+as normal (remember IO returns an unboxed pair...).
+
+Now catch# has type