Part 1

Let’s tackle the day 4 challenge!

In this one, we get an input like this:

2-4,6-8 2-3,4-5 5-7,7-9 2-8,3-7 6-6,4-6 2-6,4-8

Each line has two ranges: the first line has ranges containing 2, 3, 4, and 6, 7, 8. We must count how many pairs have ranges where one fully contains the other.

In Rust, we can express this with “inclusive ranges” (std::ops::RangeInclusive), and those implement Iterator, so we can do:

As the popular saying goes, there are only two hard problems in computer science: caching, off-by-one errors, and getting a Rust job that isn’t cryptocurrency-related.

Today, we’ll discuss caching! Or rather, we’ll discuss… “request coalescing”, or “request deduplication”, or “single-flighting” - there’s many names for that concept, which we’ll get into fairly soon.

It’s time for the Day 14 problem!

After the hassle that was Day 13, I hope this time we’ll have a relatively chill time. And, at least for Part 1, that is true.

Our input looks something like this:

mask = XXXXXXXXXXXXXXXXXXXXXXXXXXXXX1XXXX0X mem[8] = 11 mem[7] = 101 mem[8] = 0

mem is our memory. Our addresses are 36-bit wide, but as you’ll see, that doesn’t matter much.

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!

Let’s use the Advent of Code 2022, a series of programming challenges of increasing difficulty, to learn more about the Rust programming language.

So. Serializing IPv4 packets. Easy? Well, not exactly.

IPv4 was annoying to parse, because we had 3-bit integers, and 13-bit integers, and who knows what else. Serializing it is going to be exactly the same.

Right now, we don’t have a way to serialize that.

Let’s take the version and ihl fields, both of which are supposed to take 4 bits, together making a byte. We could serialize them like this:

Learning Rust is… an experience. An emotional journey. I’ve rarely been more frustrated than in my first few months of trying to learn Rust.

What makes it worse is that it doesn’t matter how much prior experience you have, in Java, C#, C or C++ or otherwise - it’ll still be unnerving.

In fact, more experience probably makes it worse! The habits have settled in deeper, and there’s a certain expectation that, by now, you should be able to get that done in a shorter amount of time.

Once upon a time, @Cinememer wrote some alternative lyrics to “Under The Sea”. I couldn’t resist singing them!

I unfortunately lost the audio files for this. Oh well.

• Instrumental (Neverland Orchestra)

The front end of the pool

I’ve been interested in reactive JavaScript for a while. At memoways, we strive to build snappy user interfaces for clients who like to interact with their data with as little latency as possible.

In the past two years, I learned front-end development on-the-fly, as the needs of the clients required it. Two years ago, I was still using jQuery. Then, I discovered space-pen thanks to my colleague Nicolas. It was nice to have proper ‘view’ objects, and use jQuery’s event system to have messages propagate throughout a hierarchy.

The bleeding edge of rustc and clippy

Typically, you’d want a production application to use a stable version of Rust. At the time of this writing, that’s Rust 1.65.0, which stabilizes a bunch of long-awaited features (GATs, let-else, MIR inlining, split debug info, etc.).