Using Moscow ML under plain DOS
-------------------------------

If you use mosml under plain DOS, then you need an external editor
such as DOS `edit' to edit your ML source files.  

Assume that the source file you want to edit is called "gcd.sml".
Then you can invoke the editor from within the ML session by
evaluating

	system "edit gcd.sml";

When returning from the editor, you can load the source file by
evaluating

	use "gcd.sml";

This works, but is tedious.  To simplify the calls to edit and use,
use the following program in file mosml\lib\edit:

(* ---------------------------------------------------------- *)
   local 
      val file = ref ""
      fun setit "" = !file
	| setit s  = (file := s; s)
   in 
      fun e s = (system ("edit " ^ setit s); use (setit s))
   end
(* ---------------------------------------------------------- *)

You may invoke Moscow ML with

	mosml edit

Then, inside the mosml session, you may evaluate

	e "gcd.sml";

This will invoke the DOS editor `edit' on file "gcd.sml".  When you
are finished editing the file, save it, and exit the editor.  Then the
edited file will automatically be loaded into the current mosml
session by `use'.  (If you prefer to use e.g. the Turbo Pascal editor,
then replace "edit " by "turbo " in function `e' above).

The call to the `e' function saves the filename, so if you need to
edit the same file "gcd.sml" again, you need to type only

	e "";

This will edit (and then use) the file most recently edited.