Ben, I agree with you that is a great idea! I can add a few more real world examples: * we get exception from a foreign library that we bound, * we get an exception from a platform (I believe Windows supports throwing exceptions to programs), * user presses CTRL-C and we want to know where our program hanged. * we get infamous <<loop>>, because in theory nobody wants non-terminating programs, but in practice everybody gets them sometimes. I also use `ExceptT`, `EitherT` for processing large sets of data, because that allows me to contain the errors efficiently. However from time to time, I get an error to blow up **and I cannot even locate which library was guilty**. It would be nice to extract them automatically and put them into error database before they are prioritized. -- Cheers Michał