See https://adventofcode.com/2020

Twitter thread: https://twitter.com/chrsnjk/status/1332126685819449344

• I'll be using the Common Lisp language (next year maybe I'll try another one)

• Each day will be associated with a different branch (or tag, once it needs not move anymore), i.e. d01, d02, etc. as well as a tag that identifies the starting point for each day, e.g. d02.start, etc. Commits between a dN and the next dN+1.start are refactorings, etc. Commits between dN.start and dN are all associated to the puzzle for that day.

• One package per day, named aoc2020.dd where dd is the day (e.g. 01, 02, ..). Typically puzzles have two parts, so each package is going to export symbols part-1 and part-2 as functions.

• I'll use libraries if necessary, as a way to show what can be done in actual programs

• I'll comment the code to explain difficulties, but some knowledge of Lisp is assumed

• To avoid unhealthy behaviours and because I don't have much spare time, and also because it's supposed to be fun, I won't be forcing myself to post a solution each day, I'll allow to let the challenge end in January if necessary.

Install quicklisp.

Clone the repository in ~/quicklisp/local-projects/ and call (ql:quickload :aoc2020).

In the source directory, calling make will test loading the code with sbcl and running tests, which is useful to guard against discrepancies between the source code and the changes made in the live environment.