I couldn't agree more. I honestly find it rather baffling that someone would write a book on not just regular expressions in general, but one particular variant

I couldn't agree more. I honestly find it rather baffling that someone would write a book on not just regular expressions in general, but one particular variant in one particular language. I've been writing code for over 15 years and if I said I had reached for regular expressions maybe 10 times in that entire time, I'm pretty sure I wouldn't be off even by an order of magnitude. There are very few cases where they're the appropriate tool, I think. They don't compose(unless you use a higher level library that lets you construct them declaratively maybe), they are hard to read and hard to debug and nearly impossible to extend. In my opinion, parser combinators are state of the art for building parsers. They can read like prose, are very easy to extend and usually easy to debug as well since you can easily get detailed error messages.