Warming up for Advent of Code 2021, I'm taking some time to practice on 2018, to refamiliarize myself with writing in Haskell (which I don't get to use professionally). This year I'm also using a branch of Justin Le's scaffolding for a Haskell project to solve AOC puzzles.
This scaffolding integrates with the Haskell AOC API to do things like pull down the puzzle descriptions, example input data, and puzzle data from the AOC website, and provides a consistent approach to representing a solution. With this scaffolding one can focus on solving the problem. If you're interested in AOC and Haskell, I strongly suggest looking at Justin's work. I for one find it very useful as a learning tool!