The Advent of Code is not a sprint: it’s a marathon: sometimes you’ve got to stop and smell the roses.

I… what? That’s not.. have you done a marathon before?

No, and I haven’t taken any creative writing classes either, I think you can tell. Anyway: Day 8 was a bit aggravating for me. In 2020 I gave up AoC after Day 14 I think, and then I skipped a year. It doesn’t help that it overlaps some holidays and stuff, but!

In our last article, we managed to load and execute a PIE (position-independent executable) compiled from the following code:

; in `samples/hello-pie.asm` global _start section .text _start: mov rdi, 1 ; stdout fd lea rsi, [rel msg] mov rdx, 9 ; 8 chars + newline mov rax, 1 ; write syscall , , "hi there", 10

I use the draw.io desktop app to make diagrams for my website. I run it on an actual desktop, like Windows or macOS, but the asset pipeline that converts .drawio files, to .pdf, to .svg, and then to .svg again (but smaller) runs on Linux.

So I have a Rust program somewhere that opens headless chromium, and loads just the HTML/JS/CSS part of draw.io I need to render my diagrams, and then use Chromium’s “print to PDF” functionality to save a PDF.

Let’s use the Advent of Code 2020, a series of programming challenges of increasing difficulty, to learn more about the Rust programming language.

Disclaimer:

Trigger warning: depression, talk of suicide.

It’s been a while since I wrote a mental health piece — but I think it’s important to occasionally stop, take a breather, and think about how we feel.

So.

deep breath

I’m okay, I think? Just a little restless.

A bit of personal context

For those keeping score, I went through major life events in 2023 — a divorce, a move, and the news that I might need a second round of jaw surgery.

It’s refactor time!

Our complete program is now about a hundred lines, counting blank lines (see the end of part 3 for a complete listing).

While this is pretty good for a zero-dependency project (save for pretty-hex), we can do better.

First off, concerns are mixed up. In the same file, we:

• Expose LoadLibraryA / GetProcAddress
• Expose the Win32 ICMP API

Unfortunately, the ooc language could have better documentation. In the meantime, I’d like to blog about about some features that might not be very well-known.

Nested functions

Here’s a program that prints 1, 3, 5, 7, 9:

import structs/ArrayList main: func { list := ArrayList<Int> new() addIfOdd := func (i: Int) { if (i % 2 != 0) list add(i) } for (i in 0..10) { addIfOdd(i) } list map(|i| i toString()) join(", ") println() }

Day 9’s problem statement is convoluted - the “ah maybe that’s why I don’t usually do Advent of Code” kind of convoluted, but let’s give it a go anyway.

So, we have a series of numbers, like so:

35 20 15 25 47 40 62 55 65 95 102 117 150 182 127 219 299 277 309 576

And uh the first N numbers are a “preamble” and every number that comes after that must be the sum of any two of the numbers that come before it.

Some bugs are merely fun. Others are simply delicious!

Today’s pick is the latter.

Reproducing the issue, part 1

(It may be tempting to skip that section, but reproducing an issue is an important part of figuring it out, so.)

I’ve never used Emacs before, so let’s install it. I do most of my computing on an era-appropriate Ubuntu, today it’s Ubuntu 22.10, so I just need to:

I have long been at war against Rust compile times.

Part of the solution for me was to buy my way into Apple Silicon dreamland, where builds are, like… faster. I remember every time I SSH into an x86_64 server, even the nice 64-core ones.

And another part was, of course, to get dirty with Rust itself.

I wrote Why is my Rust build so slow?, which goes in-depth into rust build performance, down to rustc self-profiling even!