/advent-of-code-2020

Common Lisp answers to the Advent of Code 2020 puzzles

Primary LanguageCommon LispGNU General Public License v3.0GPL-3.0

Advent of Code 2020 in Common Lisp

I'm using the Advent of Code 2020 to exercise my Common Lisp muscles.

https://adventofcode.com/2020

Learnings

Common Lisp is an enormous language with a rich library ecosystem. It's easy to get stuck in the same old corner of the language you are familiar with. What I love about the Advent of Code event is the opportunity to see how other hackers tackle the same small problems. Here are some of my personal learnings from 2020.

  • labels is like flet but allows for recursion
  • Check that a value is within a range thusly: (<= min value max)
  • You can map any sequences, for example (map 'string #'fn "ssdfs")
  • cl-ppcre:register-groups-bind simplifies text extraction
  • parseq can be an even nicer text parsing tool
  • alexandria:xor is Common Lisp's missing xor
  • metabang-bind can simplify code that requires multiple different kinds of bindings
  • alexandria:map-combinations and related functions are nice

Anthony Green green@moxielogic.com