Redbean embraces and extends Lua. That's good since Lua by itself is the most austere language. For instance, here's Lua's standard library as shown by redbean auto-completion: https://redbean.dev/img/lua-stdlib.png It only covers stdio functionality, since that's traditionally the only thing that's been portable across platforms. What we did with Cosmopolitan Libc was make POSIX as a whole portable to things like Windows. Redbean uses it to offer you a much larger breadth of system functionality across platforms https://redbean.dev/img/redbean-unixlib.png so you can benefit from the modern features of your operating system. We've also added language features to Lua that we borrowed from C and Python. https://redbean.dev/#enhancements

If you want to move your code to a different Lua environment, then you can take our APIs with you. For instance, our enhancements to Lua are all open source and built on standardized interfaces. We even offer a 420kb build of just the lua command + our unix module, in the event you ever need just Lua but not the web server too. https://redbean.dev/lua.com