Lua has always supported integers, as a compile time setting. Instead of having a full numeric tower, it has a LUA_NUMBER type that can be changed (doubles, by default), and also makes adding new numeric types at runtime (such as libGMP bignums) easy via metatables and dynamic linking.
While this may seem strange, keep in mind that Lua is designed for scripting code in another language. It tries to assume as little as possible.
What is Next for Lua: A Personal Perspective https://www.youtube.com/watch?v=izhUbMGUIPE