i wanted to add lambdas to JS, this was back in 2001 i think, so i had this compiler from my compiler class, changed it to parse JS (+ my extra features like the ()=>{} syntax) and generate an AST in XML (instead of emitting bytecode), then i made a python script that took the XML and generated minified JS from it.
Neat! I did something similar, not quite as big, but I was on a version of Python (Jython) that didn't yet have generator expressions, so I made a generator expression evaluator, gg("x for x in it") that returned a running generator. I was about a week away from shipping an ETL tool to the customer and this allowed me to hit that deadline.
