Building a parser for fun and profit

There's a rite of passage at OpenRewrite & Moderne: stick around long enough, and eventually you'll write your own parser. To challenge myself (whilst condemned to home), I wrote a Dockerfile parser, unhindered by any idea of what I was doing. I'll take you through how me and my buddy Claude built a parser from scratch, using the sexy as ever ANTLR4, and hooked that into OpenRewrite for all to use. I'll show you the highs and lows of merged and rolled back PRs, and the many, many mistakes learnings along the way. All the fun of grammars and parsers condensed into a 30 minute slot!