The history behind: https://lerax.me/programming/lisp-inference/

I did something like this as a small stackoverflow answer in 2015.

https://stackoverflow.com/questions/29963269/boolean-express...

Quite recently I revisited the parser part of the and used it as the starting point for adding comprehensive infix syntax support to TXR Lisp.

That's still only 300 lines of code, in one file:

https://www.kylheku.com/cgit/txr/tree/stdlib/infix.tl