Jangle

Summary

Jangle is a Haskell starter project for Advent of Code.

Feature overview

• Automatic downloading + caching of puzzle inputs
• CLI for running puzzles
• Automatic puzzle detection + registration

Quick-start

Project setup

First, clone or fork this repo and change directories into the repo.

Note

If you're a nix user you can skip the following steps and instead run: $ nix develop

Use Cabal to build and run this project.

Configure authentication

Jangle needs a session token from adventofcode.com in order to download your puzzle inputs and submit your answers.

Start by logging in to adventofcode.com, then browsing to one of the puzzle dashboards (e.g. https://adventofcode.com/2015).

Open your developer tools and reload the page. This should issue a GET request, e.g. GET https://adventofcode.com/2015. Look for the Cookie: request header, which should contain a value that looks like (where x is a hex value):

session=5xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx5

This value is your session token. You'll need to store it as an environment variable called AUTH_TOKEN. One convenient way of doing this is to use a tool like direnv, e.g.:

.envrc:

export AUTH_TOKEN="5xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx5"

Tip

If you don't want to configure authentication, you will manually need to create your input directories and files. This can be done by creating the following directory structure from the project root:

$ mkdir inputs/{year}/{day}.txt

where Day 01 of 2023 would look like:

$ mkdir inputs/2023/01.txt

Working on problems

Each problem module needs to expose two functions -- runProblemOne and runProblemTwo -- both of type Text -> Text.

Problem module names be of the format "Problem__.hs" -- e.g. "Problem_2023_01.hs". The numbers in the module name are parsed at compile time, and registered in the Problems.All module.

Running problems

Once you've added your problem, you can test your solution by running it with cabal. This will output your answer to the terminal:

$ cabal run jangle-exe -- \
  --year=2023 \
  --day=1 \
  --part=1

  # output 
  your_answer

Tips and tricks

Testing against other inputs

Advent of Code typically provides smaller inputs, in order to check that your code works. I tend to allow Jangle to download the puzzle input first, then I can replace the puzzle input with whatever input I'd like to test.

I can then revert back to the official puzzle input by deleting the file (Jangle will download a fresh copy when I run it again).