We’ve achieved our goals already with this series: we have a web service written in Rust, built into a Docker image with nix, with a nice dev shell, that we can deploy to fly.io.

But there’s always room for improvement, and so I wanted to talk about a few things we didn’t bother doing in the previous chapters.

Making clash-geoip available in the dev shell

It took a hot minute.

Try several weeks.

Well, yeah. I got to contribute to a bunch of open-source projects in the meantime though, so I’m fairly pleased with it!

• libffi (for static linking)
• cairo (more static linking!)
• proxy-libintl (more static linking!)
• expat (static linking strikes again)
• poppler (for file descriptor stuff not properly gated on Windows, closed in favor of a similar MR)

Today I am joining you from the relative discomfort of my living room (since my better half has commandeered the home office due to Way Too Many Calls) to tackle the day 6 challenge, which I’m excited about: maybe despite, maybe because of, the low-grade fever I’m under.

Part 1

Our input is a jumble of letters, and we’re supposed to find the position of the first substring that’s “four different characters”.

When I launched my Patreon, I vowed to explain how computers work. But in 2019, computers rarely work in isolation. So let’s take the time to write a few articles about how computers talk to each other.

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!

I’ll keep updating this article as I go, just to put stuff in all the same place.

Platforms

Cross-compiling for Linux

I’m pretty sure it’s possible to cross-compile for Linux on other OSes, seeing as everything is open-source, but I have never done it - and why would I want to? Linux is the friendliest to build on, so it’s better to use it as a build environment.

There’s a question that always comes up when people pick up the Rust programming language: why are there two string types? Why is there String, and &str?

My Declarative Memory Management article answers the question partially, but there is a lot more to say about it, so let’s run a few experiments and see if we can conjure up a thorough defense of Rust’s approach over, say, C’s.

The last article, Position-independent code, was a mess. But who could blame us? We looked at the world, and found it to be a chaotic and seemingly nonsensical place. So, in order to blend in, we had to let go of a little bit of sanity.

The time has come to reclaim it.

Short of faulty memory sticks, memory locations don’t magically turn from 0x0 into valid addresses. Someone is doing the turning, and we’re going to find out who, if it takes the rest of the series.

Let’s play a game: your objective is to guess a word, but you can only ask yes or no questions. You should also aim to ask as few questions as possible.

You might have played a variant of this game before, guessing famous actors or musicians. You’d usually ask questions like “Are they alive?”, or “Have they won an Oscar”? And that would allow you to narrow down the possibilities, until you finally resort to a list of direct guesses (“Is it Amy Adams?”) or simply give up.