MiniScriptEval VS ms-ms

Last week, we talked about the Pratt parsing algorithm. Prior to learning about that, I had always written recursive-descent parsers, including one a couple years ago that could evaluate simple numeric expressions.

Note that dependsOn is a list of monkey names; we look up the corresponding Monkey objects in a global map called monkeys. Also, to avoid writing code to handle the four different operators, I used the eval module from this repo to evaluate an expression based on the monkey's operator.

That "Operation" line is a problem. MiniScript does not have a built-in eval function (though there is a repo for that). If I weren't under time pressure, I'd probably write a very simple expression parser and evaluator that can parse and evaluate A op B, where A and B are either "old" or a number, and op is either '+' or '*'. But this being Advent of Code, I was under time pressure. That seemed like a poor choice.

If you need to evaluate expressions involving lists or maps, or basically arbitrary MiniScript code, then this little parser is probably not for you. In that case consider the ms.ms project instead.