> The Obj module allows nearly direct access to the memory image of the
> Caml runtime system.  My small program explains usefulness and danger
> of this module.  The "show_val" function takes an arbitrary Caml value
> and prints out their internal representation.

I should  mention that  I also  wrote such a  function to  display the
internal representation of ocaml values some time ago, which of course
makes a great use of Obj.magic. It is available here:

      http://www.lri.fr/~filliatr/ftp/ocaml/display/

For a direct access to the documented code with an example, see:

      http://www.lri.fr/~filliatr/ftp/ocaml/display/display.ps.gz

-- 
Jean-Christophe Filliatre    
  Computer Science Laboratory   Phone (650) 859-5173
  SRI International             FAX   (650) 859-2844
  333 Ravenswood Ave.           email  filliatr@csl.sri.com
  Menlo Park, CA 94025, USA     web    http://www.csl.sri.com/~filliatr