I did a few days of AoC in 2020 in λProlog (as a non-expert in the language), using the Elpi implementation. It provides a decent source of relatively digestable toy examples: https://github.com/shonfeder/aoc-2020

(Caveat that I don't claim to be a λProlog or expert.)

All examples showcase the typing discipline that is novel relative to Prolog, and towards day 10, use of the lambda binders, hereditary harrop formulas, and higher order niceness shows up.