Author: Andy Balaam

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…

During my work on RFC 8771 The Internationalized Deliberately Unreadable Network NOtation (I-DUNNO) I have come across a number of questions. I am documenting them here so I can send them to the authors and try to improve my understanding of the intent…

At the ACCU Conference last week I learned about RFC 8771 The Internationalized Deliberately Unreadable Network NOtation (I-DUNNO) from Jim Hague, and thought it would be fun to knock up a Rust implementation. The project is here: gitlab.com/andybalaam…

Sent via WriteToThem on Monday 1 March 2021. Dear Ben Spencer, Your experience on the front line in medicine means you are probably much more able than I to imagine the human impact of the situation in Yemen. On Sunday OCHA stated that 16 million peopl…

I’ve added the first features intended to make Smolpxl games work well on touch interfaces like phones and tablets: I’ve added a button bar at the bottom (and moved the navigation buttons to the top). I’m looking for feedback on this: Does it work on…

I learned quite a bit today about how to think about concurrency in Rust. I was trying to use a Semaphore to limit how many open sockets my TCP listener allowed, and I had real trouble making it work. It either didn’t actually work, allowing any number…

Here is the email I just sent to the organisation I volunteer for. Feel free to adapt and use in your context. Dear [organisation leaders], Much of the tech industry (e.g. [1]) is warning against the use of WhatsApp due to its policy of collecting and …

I just streamed about 40 minutes of me playing Trials Fusion using Owncast. Owncast is a self-hosted alternative to streaming services like Twitch and YouTube live. Normally, you would need to pay for a computer to self-host it on. Owncast suggest this…

I got a Pinephone for Christmas! Here is quick summary of my experience with it. (Originally published on mastodon.) Update on the pinephone as promised. I love it, but I would definitely not recommend expecting to use it as your actual phone. I have …

Maybe everyone knows this already, but for my own clarity, I think there are really two types of computer program: A function: something that you run, and get back a result. Example: a command-line tool like ls A service: something that sits around wa…

Some Java code with bugs Here’s my main method (in Java). Can you guess the bug? Db db = new Db(); Monitoring monitoring = new Monitoring(); Monitoring mon2 = new Monitoring(); Billing billing = new Billing(db, monitoring); monitoring.setDb(db); runMa…

I’m looking into Edge computing at work. By Edge computing I mean running WASM programs in lots and lots of smallish computers in places near to actual people (rather than in huge cloud data centres). I think it’s cool because I love Rust, and Rust is …

Are you writing schema upgrade code? Then I humbly suggest you take the time to write schema downgrade code too. “Why would I do that?” you might well ask, “I won’t ever need to downgrade.” Now, I imagine you’re expecting me to say you actually will ne…

You can make levels for Rabbit Escape!

It’s a very early beta for now, but I’m ready to announce Smolpxl Scores, which provides high-score tables for Free and Open Source games. Each game can have multiple high-score tables – for example, you might want one for each level. At the moment it’…

I upgraded to Ubuntu 20.04.1 and chose to keep my existing config files, and my mail server stopped working. In the log I saw: Nov 25 09:07:57 machine dovecot: imap-login: Error: Failed to initialize SSL server context: Can’t load DH parameters: error:…

Letter I sent to my MP today on the overseas aid budget. Let’s not be foolish. Dear Ben Spencer, Please use your influence to persuade the government to maintain our overseas aid budget commitment at 0.7% of national income. I believe that changing th…

I have a unit test that is running slowly, and I want a quick view of what is happening. I can get a nice overview of where the code spends its time by adding this to the JVM arguments: -agentlib:hprof=cpu=samples,lineno=y,depth=3,file=hprof.samples.tx…

Recently I’ve been having a lot of fun working on Smolpxl, which is a web site featuring some little retro web games that are all Free and Open Source Software. Here’s a sneak preview of the game I am working on: Why do this? Apart from the fact that …

Welcome! We are going to code a whole snake game. It’s going to look like this: It doesn’t matter if you have never written any code before: I am going to try and explain everything from scratch. I’m going to assume you are using a Raspberry Pi. but y…

I love simple games: playing them and writing them. But, it can be overwhelming getting started in the complex ecosystems of modern technology. So, I am writing the Smolpxl library, which is some JavaScript code that makes it quite simple to write simp…

I was looking for the right way to make a “Share This”-style button for my tiny games site Smolpxl, and I found shareon which worked exactly the way I wanted (load the JavaScript and call a function to display the buttons, with no privacy concerns), an…

I’m working on a little JavaScript library called Smolpxl. It aims to make it really easy to create retro-style pixellated games that run well in the browser, using simple JavaScript. This is me live-streaming writing a tiny “game” using Smolpxl: To …

Sometimes I run grep commands that search files with hugely-long lines. If those lines match, they are printed out and spam my terminal with huge amounts of information, that I probably don’t need. I couldn’t find a tool that limits the line-length of …

To set the date when a photo was taken, install ExifTool e.g.: sudo apt install libimage-exiftool-perl # If on Ubuntu sudo dnf install perl-Image-ExifTool.noarch # If on Fedora And modify the photo with a command like this: exiftool -DateTimeOrigina…

SMPP is a binary protocol used by phone companies to send text messages, otherwise known as SMS messages. It can work over TCP, so we can use netcat on the command line to send messages. A much better way to understand this protocol is to use Wireshark…

Here is the text of a letter I wrote to my MP today via writetothem.com: Dear [], I am writing to you to express my growing horror at the ongoing police violence and brutality Black protesters are facing in the US, and the UK’s disturbing silence on t…

I’ve spent the last couple of days fighting the Android command line to set up a simple project that can run automated tests inside an emulator reliably and repeatably. To make the tests reliable and independent from anything else on my machine, I want…

I am building a toy project in Rust to help me learn how to deploy things in AWS. I’m considering using Elastic Beanstalk (AWS’s platform-as-a-service) and also Kubernetes. Both of these support deploying via Docker containers, so I am learning how to …

I was recording some podcast audio tonight and wanted to be able to press a single key when I reached a significant moment, so I could add the times to the show notes. I couldn’t find anything that already did this, so I wrote a tiny bash script. I ran…

I love Bash tab completion, and I want it for the command I am writing, so it can automatically complete parts of the command line when I run my program. Code Here is the script (install-bash-completion) I wrote to set it up (no need to be root – it in…

I am loving writing code in Rust. So many things about the language and its ecosystem feel so right*. * For example: ownership of objects, expressive type system, compile to native, offline API docs, immutability, high quality libraries. One of the thi…

I tried to describe the main ideas that will help you write decent React code. Maybe it will help you understand the docs a bit more when you read them… Slides: React Concepts slides

I have not found an automated way to generate a nice PDF from some slides written in HTML – if you know of one please add a comment! In the meantime, if you create slides using my HTML Slides template, then you can make a decent-ish-looking PDF like th…

The Software Freedom Conservancy helps Free/Open Source software projects by providing infrastructure, financial structures, and legal help. It is a not-for-profit organisation that is dedicated to software freedom, something that I think is an importa…

What it was like to write a snake game in KotlinJS: Slides: Snake in KotlinJS slides Code: github.com/andybalaam/snake

At my job we have done a great deal of work to remove Guice from our codebase. Here I try to explain why we did that, and try to apply my reasoning to dependency injection frameworks in general. Slides: Dependency Injection frameworks: reasons to avo…

This week we did a coding workshop exercise: 2 teams implemented the different sides of the SMPP protocol (without speaking to each other) and this morning we tried out connecting them together. We successfully sent a message and received an acknowledg…

To build a “fat” Jar of your Java or Kotlin project that contains all the dependencies within a single file, you can use the shadow Gradle plugin. I found it hard to find clear documentation on how it works using the Gradle Kotlin DSL (with a build.gra…

Our mission: to create a self-signed certificate for an Apache web server that allows us to connect to it over HTTPS (SSL/TLS) from a Java program. The tricky bit for me was generating a certificate that contains Subject Alternative Names for my server…

Here is the live version of my talk designed to help you advocate for adopting Kotlin: