What about just \lua{}? Much shorter and I think more intuitive than any
lua+combination.
In my opinion only, I think this is too short for a "programming" macro. Say I want to print "lua" in my document in some typeface, then \lua would be a natural macro to use. Instead, it's taken up by this primitive that few *document* authors will ever want to know about.
"\luadirect" seems like a fine choice to me. Will
