Author: Andy Balaam

Writing our own multi-producer-single-consumer (MPSC) queue using async Rust. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Async): 34: What is…

We talked about how Futures have poll methods, but who calls them? That is the job of the runtime. We talk about how to launch your async code and how to choose the right runtime, and then we have a very brief look at some Web frameworks that are based…

Attempting to explain as slowly as possible what actually happens when the compiler finds an async function containing awaits: it writes a poll method for you to create something that implements Future. The generated poll method polls the Futures you a…

Exploring what a Future is in async Rust and how we could manually write code that polls futures. Normally, we avoid this manual work by using the async and await keywords, but looking into this helps us understand what those keywords really do. Serie…

What async programming is and what it looks like in Rust. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Async): 34: What is async?, 35: Futures…

Following through an exercise using a trait object with dynamic dispatch to choose different behaviour at runtime. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Uns…

I am really excited to say I was elected to the Governing Board of the Matrix Foundation! I was really surprised because there were lots of people standing, and the quality of the candidates was very high, but I am one of the lucky ones. I hope I can d…

Trying out the typestate pattern by tracking the state of a 3D printer by changing our type instead of updating a variable whenever it changes. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and paralleli…

Some good patterns to follow in your code e.g. “newtype”, “typestate” and one to avoid. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Trait obj…

Some good patterns to follow in your code e.g. “newtype”, “typestate” and one to avoid. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Trait obj…

Trying to explain why the rules for object safety are the way they are, and how to create and use a trait objects. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Uns…

Explaining how to hold on to something even when we don’t know its exact type, just what trait it implements. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe T…

Huge thanks to Micah Scott for hosting my videos on diode.zone until recently. My videos are moving to video.infosec.exchange/a/andybalaam – please update all your feeds. (Thanks to Jerry Bell for running that – please donate!) You can follow this blog…

I received a very kind email today from someone who had found my page Resources for year 6 teachers on coding and programming helpful, and wanted to suggest another link for me to add, about AI resources. I’m sure it was a helpful and useful link, but …

Implementing a simplified form of Mutex. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Concurrency and parallelism): 24: Parallelism, 25: Threa…

Searching across multiple documents in parallel with Rayon. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Concurrency and parallelism): 24: Par…

Update: I just discussed this with my son and I really want to emphasise: It does make a difference who is in power. The previous Labour government significantly improved primary education and many other public services. Don’t lose hope! Here are the c…

How to spawn threads and deal with lifetimes, how to send or share state across threads, and what Send and Sync mean. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, …

What concurrency and parallelism are, a brief intro to Rayon, and a quick note on closures. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Concu…

Testing, benchmarking and optimising a small program that plays FizzBuzz. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Building applications):…

Building a command-line quiz application to bed in our knowledge about crates, modules and serialisation. All done using test-driven development. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and paralle…

Going through an exercise on serialization with serde. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Building applications): 18: Dependencies, …

How to write unit tests in your Rust code, and some quick pointers on writing integration and benchmark tests. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe …

I have decided to stand for election to the Matrix Governing Board, which is a brand new body which advises and oversees the work of the Matrix Foundation. I will stand as an Individual Member, not representing a company or project. Contents: Purpose …

Tips and rules for writing good APIs that are easy for other people to use. Try to make them Unsurprising, Flexible, and Obvious. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait obje…

How to describe details of your Rust project with a Cargo.toml file, and how to find and add dependencies (other people’s code). Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objec…

Finishing off the exercises on Rust traits, designing a customised version of Vec. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Traits and gen…

DON’T DO THIS: the Signal app has the ability to make daily backups of your messages, and when you choose a folder to backup into, you can choose “Nextcloud” as the device, then choose a Nextcloud folder to back up to. Don’t do that. Although the above…

Going through some exercises on Rust traits, designing a customised version of Vec. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Traits and ge…

Rust has a feature where if you import two things from the same module you can abbreviate it like this: use mypkg::{MyStruct1, MyStruct2}; If you prefer, you can keep them separate, like this: use mypkg::MyStruct1; use mypkg::MyStruct2; I do prefer. St…

This time we tackle one of the most tricky areas for a new Rust programmer: lifetimes. The key point is that when we add lifetime bounds (‘a or similar) to a function signature, this is not to help Rust compile our function: it’s to help Rust understan…

A tour of some of the most interesting traits in the standard library including Add etc. to overload operators, Sized, Sync and Send for telling the compiler special things about your type, Clone and Copy for copying things, Into and From for convertin…

Following on from video 12, looking at how to add type information to traits, to make them flexible enough to describe generic code with different types, for example how to add a u32 to a u64 and return a u128, without defining a whole new trait for ev…

Explaining what a trait is, and how to use it. A trait is a bit like an Interface in Java or Go, or an Abstract Base Class in C++ or Python, but it can be used to define behaviour at compile-time as well as at run-time. We go through an example of why …

Going through some exercises on Rust ownership, references, slices and error handling. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (More synta…

Update: as confirmed in the bug I logged, this was fixed in Firefox 123! See also: Keep your Indexed DB keys and values small if you want good performance! and Don’t store arrays of numbers in Indexed DB – use base64 instead. We had performance problem…

Following on from Keep your Indexed DB keys and values small if you want good performance!, here is another thing I’ve learned about Indexed DB performance (in July 2024): Update: Thanks to richvdh, we now know UInt8Array is much better than base64! If…

What a String is in Rust, and how they differ from &str. Strings are resizeable arrays of bytes that are guaranteed to be in UTF-8 format. &strs are references to chunks of bytes that are also guaranteed to be in UTF-8 format. If you want to le…

In our work recently on Element Web (specifically attempting to replace our encryption code with our cross-platform Rust implementation) we’ve noticed some strange behaviour with the performance of our Indexed DB queries. We’ve been aware of some slowd…

Explanation of some of the most commonly used types in Rust: Vecs, which store lists of items, Boxes that allow us to own things that we keep on the heap, and slices that are a way of referring to parts of Vecs or arrays without owning them. Series: L…

This time we discuss how to add methods to structs and enums, using impl blocks. Methods work similarly to other languages, but it might be a surprise that they can be defined inside separate blocks, and in fact they can be defined in multiple differen…

We learnt about enums and generics last time, which means we’re ready to talk about Result, which is a really nice way of handling errors in Rust, that allows you to be very explicit about what went wrong, but also with a very compact syntax using the …

Dear Ben Spencer, The behaviour of Hamas on 7th October and afterwards is inexcusable, and is rightly condemned by our government. I believe that the ongoing behaviour of the Israeli government in response to these attacks is inexcusable, and should be…

Santa Circles 0.3 is all new and shiny! santacircles.artificialworlds.net (It’s a secret-santa-style gift exchange web site.) Don’t worry, it looks exactly how it did last year, except there is a tiny “Forgot password?” link you can click if you need …

If I’ve set it up right, you can now follow this blog on Mastodon and other fediverse platforms! Search for this user: @blog@www.artificialworlds.net

Continuing our review of the things you need in Rust to write programs – grouping together data using structs, and allowing multiple possibilities with enums. We look at how to decide which thing you’ve got with the match keyword, and review a very pop…

Starting some more advanced Rust programming ideas by looking at references – the ability to “borrow” values and refer to them without taking ownership. We look at mutable and immutable references, and the rules about references that prevent us ever ha…

Going through some exercises on basic Rust syntax and ownership. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Language basics): 1: Intro, 2: L…

Continuing on Rust programming basics by looking at ownership and memory management, including the stack and the heap: what they are, how they differ, and why you need to care. For more help on ownership and the stack and the heap, try Chapter 4 of th…

An introduction to the Rust language basics. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Language basics): 1: Intro, 2: Language basics, 3: M…

Introducing the Rust 101 series and how to install Rust. Series: Language basics, More syntax, Traits and generics, Building applications, Concurrency and parallelism, Trait objects, Async, Unsafe This section (Language basics): 1: Intro, 2: Language …

Combining interfaces/objects with & When you combine two types in TypeScript with & (ampersand), it is called an Intersection Type. For example: interface Particle { mass: number; } interface Wave { wavelength: number; } type Both = P…

I use Podman to provide Docker-like stuff on my dev machine without effectively being root. Talking to the container host in Docker There is a little trick for accessing HTTP services on the container host in Docker: you add –add-host host.docker.inte…

Here’s the letter I just sent to my MP. Feel free to use it in full or in part. Dear Ben Wallace, Last night I made the decision to vote tactically against you at the next election, and I felt I owed you an explanation. I now feel that any of the likel…

Up to now I’ve been following the official guide and using webpack to package my Rust+WASM code to run in a browser. But today I found out there is no need for webpack at all! This makes development much faster, with many fewer dependencies. Setup Befo…

I was recently asked what I thought of using time-based estimates when tracking software tasks. TLDR: I think it’s a terrible idea that can hurt your software by introducing bugs and burning out developers. I think using time-based estimates is pretty …

More of my series about my favourite bits of Maths. This time, Graphs: Slides for Maths: The Fun Parts – Graphs

More of my series about my favourite bits of Maths. This time, Groups: Slides for Maths: The Fun Parts – Groups

I’ve been wanting to make series about the cool bits of Maths for years and I’m finally getting around to it. It’s called “Maths: The Fun Parts” and the first part is on Sets: Slides for Maths: The Fun Parts – Sets

Every time I try to use GitHib’s GraphQL API I find myself totally lost, so here are some snippets I have found useful. All of these can be pasted into the GitHub GraphQL API Explorer, which can run the code as your logged-in user in the browser withou…

I’ve just got off a call with a colleague. During that call I: learned a lot about how the work he is doing fits in with what my team is working on understood the specific code we were discussing much better than if I’d looked at it alone helped him f…

10 months ago I wrote a blog post Air-Source Heat Pump – our experience so far, 2 months in about our new air source heat pump. Have a look back at that for photos of the device itself and more detail about installation etc. Less energy We used a lot l…

Update: my twitter archive is here: artificialworlds.net/tweets. Update: you can see the hacky scripts I used to build this, based on twitter-archive-parser. This evening I deleted my Twitter account. I’m feeling surprisingly unsettled by doing it, to …

Geeks don’t like to be formal, but we do like to be precise. That is the contrast that comes to mind as I attend my first IETF meeting, IETF 115 in London in November 2022. Like most standards bodies, IETF appears to have been formed as a reaction to s…

The Selection API is confusing and weird. But, here’s what I’ve discovered: just use setBaseAndExtend, and when (rarely) needed, extend. Summary Every selection in a browser consists of: an “anchor” – the beginning, where you started dragging, and a “…

I’ve been working a bit with contenteditable tags in my HTML, and learnt a couple of things, so here they are. Update: See also my demo of how to select text in various ways in a contenteditable. Why can’t I see the cursor inside an empty contenteditab…

I had the pleasure of being a mentor this summer for an Outreachy internship for the Matrix organisation. Outreachy provides internships to people subject to systemic bias and impacted by underrepresentation in the technical industry where they are liv…

ffmpeg -i original.mkv -c:v libx264 -c:a aac -ac 2 -ab 384000 -ar 48000 new.mp4 (Short answer: use the above ffmpeg command line. Read on for how I did this in Tdarr.) I recently discovered Jellyfin, which gives me a Netflix-like UI for viewing my own …

Curious to know a bit more about Matrix? This video goes into the details of what kinds of requests you need to send to write a Matrix client, and why it’s interesting to write a Matrix server. Slides: Matrix is a Distributed Real-time Database Slides…

One of the advantages of writing code in Rust is that it can be re-used in other places. Both iOS and Android allow using native libraries within your apps, and Rust compiles to native. Web pages can now use WebAssembly (WASM), and Rust can compile to …

Letter to my MP on deporting refugees to Rwanda, 2022-06-06. Dear Ben Spencer, Please do what you can to reverse the policy of sending asylum seekers to Rwanda. We are breaking our proud tradition of commitment to refugees. This policy seems to have th…

I was becoming increasingly uncomfortable with how crufty my neovim config was getting, and especially how I didn’t understand parts of it, so I decided to wipe it clean and rebuild it from scratch. I did it live on stream, to make it feel like a worth…

[Updated 2022-11-17 based on the new draft of the MSC, notably removing backwards compatibility and the abbreviated forms.] (Background: Matrix is the awesome open standard for messaging that I get to work on now that I work at Element.) The Extensible…

[Update: see also Air-Source Heat Pump – 1 year later.] Summary: less energy, more money 2 months ago, we replaced our gas boiler with an air-source heat pump, which uses electricity to heat our home and boiler. This is a report of our experience so fa…

[Previous: Self-hosting maps on my laptop] In the previous post I showed how to run OSM tile server stack locally. Now I’ve managed to connect a MapLibre GL JS front end to my local tile server and it’s showing maps! Sharing a location in Element Web (…

[See also: Providing MapLibre-compatible style JSON from openstreetmap-tile-server] As part of my research for working on location sharing for Element Web, the Matrix-based instant messenger, I have been learning about tile servers. I managed to get OS…

Simulcasting RTMP using NGINX I want people to be able to watch my Matrix and Rust live coding streams using free software, so I’d like to simulcast to PeerTube as well as Twitch. This is possible using NGINX and its RTMP module. It does involve buildi…

My newest game is out now on Smolpxl Games – Tron: Play at smolpxl.gitlab.io/tron. It’s a frantic multiplayer retro pixellated thingy playable in your browser. Try to stay alive longer than everyone else! This version allows many players (up to 16 if …

Yesterday I learned that Virgin Media is inserting itself into some of my DNS requests. Much as I am not a fan of how powerful Cloudflare are, if they are telling the truth about their DNS, then it’s safe, so I followed their instructions on how to use…

[Introduction including details about my own air source heat pump install, and mention of the ending of the RHI funding in April 2022.] After I have installed an air source heat pump, I will pay more money to heat my home, even though I am using less e…

I started a new job today at Element! It has been a long-standing ambition of mine to work in Free and Open Source software, and I am very excited to work for a company that is the main developer of a really important project: the Matrix communication …

Update: caching $RUSTUP_HOME and $CARGO_HOME does not work for me – I removed them. When building your project with Gitlab CI or a similar build tool, you can end up spending a lot of time watching your build repeat the same steps over and over. This i…

To print a Maven project’s version number, try: mvn help:evaluate -Dexpression=project.version -q -DforceStdout -q suppresses all output(!) -DforceStdout unsuppresses the actual thing you asked to be printed. I will refrain from commenting on how diffi…

The Kotlin docs describe some things you need in your pom.xml to create a project that is a mix of Kotlin and Java code, but there is no complete example, so here is mine: pom.xml:<project> <modelVersion>4.0.0</modelVersion> &lt;g…

My Peertube server is shutting down, so I need to move my videos to another one. The official scripts don’t seem to cover this case very well, so here is what I did. My script fetches videos and their details and uploads them to the new server via the …

My new game, Rightwaves, is out now! It’s a tribute to the great classic R-Type. The entire implementation, including all the graphics, is contained within a single ~5000-line JavaScript file. Why? This is a terrible idea Let me start by saying I do n…

On my phone and computer I use WhatsApp, Signal, Slack, Keybase, Discord, IRC, XMPP/Jabber and Element/Matrix. In addition, I occasionally use the messaging features of Mastodon, Twitter and even LinkedIn. I’ve never used Telegram, Line, WeChat, Sessio…

This was quite a challenge, and I nearly gave up, but I managed to write a Snake game in Terraform: Slides: artificialworlds.net/presentations/snake-terraform Source code: gitlab.com/andybalaam/snake Slides source code: gitlab.com/andybalaam/videos-sn…

I have recently started using Kupfer again as my application launcher in Ubuntu MATE, and I found it lacked the ability to suspend the computer. Here is the plugin I wrote to support this. To install it, quit Kupfer, create a directory in your home dir…

PeerTube’s API documentation gives an example of how to upload a video, but it is missing a couple of important aspects, most notably how to provide multiple tags use form-encoded input, so my more complete script is below. Use it like this: # First, m…

Category Theory is an incredibly exciting and challenging area of Maths, that (among other things) can really help us understand what programming is on a fundamental level, and make us better programmers. By far the best explanation of Category Theory…

It’s hard to believe it’s already a year since the release of RFC 8771 (The Internationalized Deliberately Unreadable Network NOtation), which for me at least made me think about IP addresses in a whole new way. So, it seems fitting for the anniversary…

Lots of people are filling in the extremely detailed UK government COVID test result page twice every week. It asks you to fill in a very large list of details, most of which are the same every time, but it doesn’t remember what you typed last time. I …

The Internet is full of outdated Python code for doing things with windows, so here is what I got working today in a Python 3, GTK 3 environment. This script toggles the window decorations on the active window on and off. I have it bound to Ctrl+NumPad…