signature MLTON_EXN =
   sig
      val addExnMessager: (exn -> string option) -> unit
      val history: exn -> string list
      val topLevelHandler: exn -> 'a
   end

• addExnMessager f

adds f as a pretty-printer to be used by General.exnMessage for converting exceptions to strings. Messagers are tried in order from most recently added to least recently added.

• history e

returns call stack at the point that e was first raised. Each element of the list is a file position. The elements are in reverse chronological order, i.e. the function called last is at the front of the list.

history e will return [] unless the program is compiled with -const 'Exn.keepHistory true'.

• topLevelHandler e

behaves as if the top level handler received the exception e, that is, print out the unhandled exception message for e and exit.