doc/guide/src/MLtonExn.adoc

   1 MLtonExn
   2 ========
   3
   4 [source,sml]
   5 ----
   6 signature MLTON_EXN =
   7    sig
   8       val addExnMessager: (exn -> string option) -> unit
   9       val history: exn -> string list
  10
  11       val defaultTopLevelHandler: exn -> 'a
  12       val getTopLevelHandler: unit -> (exn -> unit)
  13       val setTopLevelHandler: (exn -> unit) -> unit
  14       val topLevelHandler: exn -> 'a
  15    end
  16 ----
  17
  18 * `addExnMessager f`
  19 +
  20 adds `f` as a pretty-printer to be used by `General.exnMessage` for
  21 converting exceptions to strings.  Messagers are tried in order from
  22 most recently added to least recently added.
  23
  24 * `history e`
  25 +
  26 returns call stack at the point that `e` was first raised.  Each
  27 element of the list is a file position.  The elements are in reverse
  28 chronological order, i.e. the function called last is at the front of
  29 the list.
  30 +
  31 `history e` will return `[]` unless the program is compiled with
  32 `-const 'Exn.keepHistory true'`.
  33
  34 * `defaultTopLevelHandler e`
  35 +
  36 function that behaves as the default top level handler; that is, print
  37 out the unhandled exception message for `e` and exit.
  38
  39 * `getTopLevelHandler ()`
  40 +
  41 get the top level handler.
  42
  43 * `setTopLevelHandler f`
  44 +
  45 set the top level handler to the function `f`.  The function `f`
  46 should not raise an exception or return normally.
  47
  48 * `topLevelHandler e`
  49 +
  50 behaves as if the top level handler received the exception `e`.