top-level-handler.sml

[Matthew Fluet]

Is there a minor bug in top-level-handler.sml:      
      fun handler exn =
         (message "unhandled exception: "
          ; let
               fun loop e =
                  case e of
                     Fail s => (message "Fail "; message s)
                   | IO.Io {cause, function, ...} => (message "IO "
                                                      ; message function
                                                      ; message ": "
                                                      ; loop cause)
                   | _ => message (exnName exn)
            in
               loop exn
            end

Should the default case in loop print the exnName of e instead of exn?
Seems that any IO exception would just terminate with "IO" instead of the
cause.