$ luarocks install color
Allows for easy access to rgb, hsl or hex by only defining one of them as well as efficient computation of other values when one changes. It also has a couple useful color conversion methods like hex_to_rgb, rgb_to_hex, rgb_to_hsl and hsl_to_rgb and the class uses those methods to calculate the other values when one value updates.
The main color class itself contains h, s, l, r, g, b and hex values which, when one is updated, updates all the others (but it does it efficiently so it's cool)
There's a better description in the github's README