Advent of Code starts tonight!

Advent of Code is an Advent calendar of Christmas-themed programming puzzles. Puzzles unlock at midnight and a leaderboard ranks how quickly participants can turn in a solution.

AoC is language-independent, so some puzzles can be solved without programming at all. Each night has two related challenges. The input is typically some sort of text key or puzzle, and the output is a short string or number that has to be entered into the web site. The second half of each puzzle will make some "small" change to the requirements, often in a way that makes the solution much harder! (Particularly if you took shortcuts in the first half.)

The set of puzzle inputs on each day is large but not infinite, so it usually doesn't work to just copy somebody else's final answer.

Each successful solution gets you a star, and the stars unlock an ASCII picture, like this procedurally-generated ASCII circuit board from 2017:

The past couple years I've given up on the leaderboard (as the contest grows, it gets harder to make it). Instead I've used it as a challenge to solve the puzzles in a new language, as many other people do.

In 2016, I used Swift: https://github.com/mgritter/aoc2016

In 2017, I used Rust: https://github.com/mgritter/aoc2017

This year I was thinking of using Haskell, but I haven't done enough pre-work that I'm sure I'll be ready tonight.