Not to further stoke the flames here - but you seem to have no option to use MIT for luaprompt - you link to readline which is GPL3. That ends the concept of using the MIT license.......
Hmmm, I totally forgot about that but still I think Kevin may be right, that you only need to GPL your application it if you actually link with readline. If you link with libedit instead for example, which is supposed to be fully readline compatible you can keep the permissive license.
