checks on exceptions

[ghost]

Yes it would, but the C library doesn't readily provide that, and we need that exception. If you can accept that, we can work on more appropriate exception in a later version.

[Kakadu]

This is useful link in the manual about this topic.

http://caml.inria.fr/pub/docs/manual-ocaml-4.00/manual033.html#s:register-exn