I used ANTLR to write a Python parser for the SNOMED expression language last year, and testing it was one of the weirder parts of the experience. I was up and

I used ANTLR to write a Python parser for the SNOMED expression language last year, and testing it was one of the weirder parts of the experience. I was up and running in a few days, which was largely thanks to the ANTLR book. I love this project. It made doing what I did a lot more fun than I thought it would be. Hand-rolling an ABNF parser from scratch would be a nice hobby project, but not when one has a deadline.