2010/3/3 Tom Hawkins <tomahawkins@gmail.com>

On Wed, Mar 3, 2010 at 6:07 AM, Ivan Miljenovic

-Wall only complains about shadow bindings, defined but not used, and
no type signature. But no unmatched patterns.

If you can run your code through the ghc debugger you can get it to break when an undefined exception is raised.

The options are :set -fbreak-on-exception or -fbreak-on-error. More info in the documentation at http://www.haskell.org/ghc/docs/latest/html/users_guide/ghci-debugger.html#ghci-debugger-exceptions

Hope that helps,
Alex MDC