Advent of Code 2021

You can view the list of puzzles at the official site.

Programming Language of the Month

Decided on Factor once I sorted out a sort of workable environment.

I'd like to do Factor or BQN, but:

getting Factor to run with source in a folder outside the language implementation itself requires messing around with env vars or other boot-time config, and getting the GUI listener (IDE and VM basically) to run seemed touch and go on macOS. Which is a shame, as the docs are mostly good, and Andrea Ferretti's Factor tutorial is comprehensive enough to get you places, if only I knew how to get started with a basic "here's how to work in a repo with Factor" walkthrough - a "second program" walkthrough, rather than "first program".

But perhaps the "use the work dir" hint from Joe Groff is enough for my needs - just symlink that?

By golly, that worked:
```
cd ~/Applications/factor  # copied from the nightly DMG
rm -r work
ln -s /ABSOLUTE/PATH/TO/adventofcode-2021/src/ work
env AUTHOR='Jeremy W. Sherman' ./Factor.app/Contents/MacOS/factor
```
And then in Factor:
```
USE: tools.scaffold
"palindrome" scaffold-work
```
Indeed created a new vocab in the target src/ folder!
BQN is entirely too foreign for me to mess around with just now. I have a decent theoretical understanding of Forth-likes, but APL derivatives? Not at all.

Owing to time constraints, I might wind up doing something boring that I already know how to use. Alas.

Fire up the GUI from the factor/ directory.
Before scripts/scaffold:
- "dayNN" dup scaffold-work scaffold-test
- pbpaste > src/dayNN/input.txt
- Copy the previous day to get the basic structure down.
Now:
- scripts/scaffold 07 # or whatever
Fill in the example, work on parsing, write some tests.

One of my keyboards sends weird F key codes.

Help: F1: \ word help
- See help for a vocab: "vocab-name" about, e.g. "assocs" about
Refresh: F2: refresh-all
Errors: F3: show-error-list