that's awesome, I wrote a Mathematica clone too! I think it's one of the most rewarding projects I've done.

The amazing thing is how Mathematica starts working with just a few simple ideas, evaluator, backtracking pattern matcher, and a REPL.

were you able to implement Condition? how advanced is the pattern matcher? I got stuck after doing Blank BlankSequence and BlankNullSequence

https://github.com/anandijain/cas3.rs https://github.com/anandijain/cas8.rs