> This is a serious question (not an argumentative one).  How do I avoid 
 > Invalid_argument when I'm expecting the user to enter a filename on
 > the command-line?  Or are you just talking in general?

You can check the size of the array before reading it:

if Array.length Sys.argv < 2 then usage ();;
let filename = Sys.argv.(1)

will never raise an Invalid_argument exception.

- Fabrice

Homepage: http://pauillac.inria.fr/~lefessan