atgreen / advent-of-code-2020

Common Lisp answers to the Advent of Code 2020 puzzles

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 [e-mail]