On Wed, 5 Aug 2009, Rob Biedenharn wrote:

> Well, it certainly isn't invalid. You can easily have a Range where the end 
> is less than the begin value.
>
> r = 3..-1
> => 3..-1
> irb> r.to_a
> => []
> irb> "hello"[r]
> => "lo"

I guess the code for substring treats it differently than #to_a -- just 
taking the bounds.  Huh.  That's pretty interesting.  Learn something 
every day.  Makes sense when I stop to think about it, though.

Just don't try "hello"[3,-1]....

I need to read the rdocs more often....
Matt