A Pratt parser for a simple language (features basic math, parenthesis and nothing more) written as an exercise following this article by the Desmos' guys. This is just a parser written for didactic purposes: it does not perform any sort of evaluation of the expressions give to it; but has a pretty printer that produces basically S-expressions so, if you really want a calculator, I guess you can pipe the output of pratt to your loyal LISP interpreter (echo "2 + 2" | pratt | sbcl -c should do the trick).

Does not require any dependency, builds and runs with the standard cargo command cargo build and cargo run.