So, I read about the fast interpreter and small language. How do something like this?

"Whitney’s strategy was to implement a core of the language – including the bits everyone thought most difficult, the operators and nested arrays – and use that to implement the rest of the language. The core was to be written in self-expanding C. As far as I know, the kdb+ interpreter is built the same way.

Unlike the tall skinny C programs in the textbooks, the code for this interpreter spills sideways across the page. It certainly doesn’t look like C."

This mean that the code is very unreadable C? Like a kind of code-golf?

How replicate it for built a speedy interpreter? And what if I use lua or python instead?