I've been searching for a few minutes and can't find it -- it was several years ago, maybe at least 5 years, and at one of the Clojure conferences (there used to be several big Clojure conferences each year back in the language's golden age, but now there's 0 - 1 per year), and I can't remember which conference.

was it this one?

https://www.youtube.com/watch?v=RvHYr79RxrQ

That looks interesting as well, but it’s not the talk I was thinking of.