Using Lua in Arduino project
Lua is an interpreted language. That is, the compile phase turns Lua source code into intermediate "pseudo-code" which the Lua interpreter then runs. It doesn't compile into machine code, and therefore there is nothing that could be uploaded to your Uno as a "hex" file.

In any case, with only 2 KB of RAM, it wouldn't be very practical to attempt to run Lua on a Uno. I like Lua personally, but running it on the (AVR) Arduinos just isn't practical.