This is one of the best plain <i>programming</i> books out there. Even if you don't have a particular interest in Lua, you'll learn something.<p>I've heard it compared it to "The Unix Programming Environment" in terms of being a classic, and I agree.<p>I find myself coming back to this book again and again, even though I haven't been able to justify Lua on any projects really. Just now the treatment of coroutines really helped with using Python coroutines (not generators).