Advent of Code 2021

Discussions of puzzles from 2021's Advent of Code.

The main goal of these posts is educational, so I try to examine the parts of the puzzles that I find interesting. In general, this means I ignore parsing puzzle input or other kinds of bookkeeping. I try to use formal reasoning and program calculation on these puzzles to whatever extent possible. I don't try to complete all of them, or to keep up with the release schedule. Languages used depend on the problem, though I often use a generic typed ML-like language to reason with. As such, only basic library forms are used, which is all for the best—there's little to be learned from digging around for the perfect pre-fab function.