Hi Nick, please note that the handler set by std::unexpected() fires only if a function violates its exception specification, i.e. the function void foobar() throw() { throw 0; } would trigger std::unexpected_handler(), but void foobar() { throw 0; } does not, because there is no "unexpected" exception. Uncaught exceptions, on the other hand, trigger the function std::terminate(), which by default translates to std::abort(). Brandon Allbery pointed this out before, but it's probably worth repeating: there is no way to catch (or throw) a C++ exception in Haskell. The internal details of C++ exception handling are "implementation defined". There is no standard that defines how to implement exceptions, which means that you cannot even mix code from different C++ compilers if you want to handle exceptions. Mixing in Haskell code is probably next to impossible. Take care, Peter