@peterdrake
I didn't get to learn Prolog, but taught myself Brachylog (https://github.com/JCumin/Brachylog/wiki) for the sake of code-golfing.
It got me thinking about data and computation in an entirely new way. Generic "this will expand your mind" claims are overdone in this field, but it felt like declarative logic programming truly did that for me after more than a decade of professional programming.