Author: Andy Balaam

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:

Here is the talk CB Bailey and I did at ACCU Conference 2019. This was the first talk I have done with someone else, and I really enjoyed it:

People at work suggested Kotlin was “just syntactic sugar”, so I set out to explain how Kotlin can really make better code, and here is the result: Slides: Examples of Kotlin making your Java code better slides

Slightly jokey video about what a Monad is, but with a genuine explanation, all in just about 5 minutes. First given as a lightning talk at the ACCU Conference in 2019. Slides: What is a Monad? Slides

To spin up a temporary environment with a different Java version without touching your real environment, try this Docker command: docker run -i -t –mount “type=bind,src=$PWD,dst=/code” openjdk:11-jdk bash (Change “11-jdk” to the version you want as li…

If you’d like to help promote Rabbit Escape, my free software Android/PC game, how about a t-shirt? Use the link below to design your shirt: Rabbit Escape t-shirt Note: there’s no profit in this for us – it’s just for promotion. If you’d like to contr…

When we want to do something later in our Java code, we often turn to the ScheduledExecutorService. This class has a method called schedule(), and we can pass it some code to be run later like this: ScheduledExecutorService executor = Executors.new…

The newest feature of Rabbit Escape, water, has been brewing a long time, but we now think it’s ready: Water can flow, it can put out fires, and it can drown rabbits. Rabbots seem to be immune though… Check out the 20 new levels we have released! (T…

Here’s a little script I wrote to avoid copy-pasting the ffmpeg command from superuser every time I needed it. It converts a video to a GIF file by pre-calculating a good palette, then using that palette. Usage: ./to_gif input.mp4 output.gif The file t…

In an insane world, Gradle sometimes seems like the sanest choice for building a Java or Kotlin project. But what on Earth does all the stuff inside build.gradle actually mean? And when does my code run? And how do you make a task? And how do you persu…

I found something difficult in Python, which was a bit of a first, so I wrote a whole blog series about it, and now a whole video: Slides: Python Async Basics slides Blog posts: asyncio basics, large numbers in parallel, parallel HTTP requests, addin…

I’ve been getting very excited about keybase.io recently, not least because it offers secure conversation, and you can have bots. I wrote a quick bot to simulate Arnold Schwarzenegger which I thought I’d share to demonstrate how easy it is. It is based…

Series: operations, images, opacity Not because I was enjoying it, I seemed compelled to continue my quest to understand the performance of various Java 2D drawing operations. I’m hoping to make my game Rabbit Escape faster, especially on the Raspberry…

Series: operations, images, opacity In my previous post I examined the performance of various drawing operations in Java 2D rendering. Here I look at some specifics around rendering images, with an eye to finding optimisations I can apply to my game Ra…

Series: operations, images, opacity I want to remodel the desktop UI of my game Rabbit Escape to be more convenient and nicer looking, so I took a new look at game-loop-style graphics rendering onto a canvas in a Java 2D (Swing) UI. For more on images,…

It was a pleasure to go to the London Python Meetup organised by @python_london. There were plenty of friendly people and interesting conversations. I gave a talk “Making 100 million requests with Python aiohttp” (slides, Blog post) explaining the basi…

Docker is useful for some things, and not as useful as you think for others. Here’s something massively useful: get a throwaway bash prompt inside any version of any Linux distribution in one command: docker run -i -t –mount “type=bind,src=$HOME/Deskt…

Windows was missing from my grub menu after I installed Ubuntu. Fortunately it was fixed by running: sudo grub-mkconfig -o /boot/grub/grub.cfg and rebooting. Phew.

After years of getting around to it, I have redesigned my home page at artificialworlds.net. It’s basically intended to make me look clever or productive or interesting or something. Alternatively, it gives you somewhere to find that thing you know I m…

There are lots of people missing from the programming world: lots of the programmers I meet look and sound a lot like me. I’d really like it if this amazing job were open to a lot more people. One of the weird things that has happened is that somehow w…

I have spent the last few hours investigating abysmal performance in my latest little game project Cross The Road. Firefox was fine, but Chromium and Chrome, especially on mobile, was rendering at about three frames per second. When I stopped using SVG…

In which I try to express the weird joy I felt learning about all the odd quirks of the simple task of turning bytes into characters, and characters into bytes. Slides: Interesting Characters slides

Series: Snake in Elm, Elm makes me happy, Elm Basics, Elm Unit Test, Elm JSON With up-to-date examples, and anecdotes from the last couple of years of continuing to enjoy writing web pages in Elm, here’s a new version of my Elm advert: Slides: Elm ma…

Series: 2D Shapes, drag and drop, new objects My Godot 3 game is progressing, and I am starting to think I am actually writing the level editor. Here’s how I wrote code to make new versions of existing objects (by converting them to scenes): Godot ve…

I am writing a CharsetEncoder in Java, which is my kind of fun. I was getting a mysterious error when I identified that I could not encode certain characters: Exception in thread “main” java.lang.IllegalArgumentException at java.nio.Buffer.position(Bu…

Series: 2D Shapes, drag and drop, new objects Continuing to explore the Godot 3 game engine. I want to make a game where you drag blocks around and balance them on each other, but I couldn’t find much documentation on how to drag-and-drop objects (exce…

Series: 2D Shapes, drag and drop, new objects In which I make a square and a triangle bounce on a rectangle using Godot 3: Godot version: v3.0.6.stable.official.8314054

Series: Snake in Elm, Elm makes me happy, Elm Basics, Elm Unit Test, Elm JSON I find JSON decoding in Elm confusing, so here are some thoughts and examples. Setup $ elm –version 0.19.0 $ mkdir myproj; cd myproj $ elm init … $ elm install elm/json …..

Because the Rapsberry Pi uses a slightly older Python version, there is a special version of Graft for it. Here’s how to get it: Open a terminal window by clicking the black icon with a “>” symbol on it at the top near the left. First we need to in…

I’m running a workshop at the Egham Raspberry Jam on 21st October. The workshop will introduce my little animation language Graft. We will tell a story using animations that we created ourselves using code. The worksheet for the workshop is here: PDF o…

Elm is unstable, so upgrading to the next version can be painful. Here’s what I needed to do to upgrade from 0.18 to 0.19. Replace elm-package.json and tests/elm-package.json with elm.json – e06f5a1728 Switch to the new elm-test – b964b7c7a Re-arrange…

If you use Wunderlist and want to be able to bulk-add tasks from a text file, first install and set up wunderline. Now, to be able to right-click a text file containing one task per line on Ubuntu MATE, create a file called “wunderlist-bulk-add” in ~/….

In a previous post I described how to install Flarum locally on Ubuntu. Here is how I set up my development environment on top of that setup so I was able to write a new Flarum extension and test it on my local machine. Recap: I installed Apache and PH…

I found out on Mastodon recently that the Compose key exists, allowing you to enter special characters using easy-to-remember key sequences (e.g. “<compose>/=” gives you “≠“). To do this on Ubuntu (and probably many other systems), hold SHIFT, …

I want all requests to artificialworlds.net/rabbit-escape/levels/ to get redirected to use the https protocol, and to include “www.” at the beginning of the URL, and I found lots of Stack Overflow articles, but nothing there worked perfectly for me. He…

Here is an almost-minimal example of a systemd service file, that I use to run the Mastodon bot of my generative art playground Graft. I made a dedicated user just to run this service, and installed Graft into /home/graft/apps/graft under that username…

I am setting up a forum for sharing levels for my game Rabbit Escape, and I have decided to try and use Flarum, because it looks really usable and responsive, has features we need like liking posts and following authors, and I think it will be reasonab…

The RABBOTS are coming! Get the latest version of Rabbit Escape: Android: Rabbit Escape on F-Droid (free, no ads) Android: Rabbit Escape Free on the Play Store (free, no ads) Android: Rabbit Escape on the Play Store (Pay about 60p, identical to the f…

I have quite a few videos hosted on YouTube that I would like to upload to my new PeerTube location, but I don’t want to install all the PeerTube dependencies on my machine, so I did it all inside a Docker image. First I built and started a Docker cont…

Recent Overload journal issues contain my new articles on How to Write a Programming Language. Part 1: How to Write a Programming Language: Part 1, The Lexer Part 2: How to Write a Programming Language: Part 2, The Parser PDF of the latest issue: Overl…

I love the “tiling” feature in many window managers including Marco that means I can drag windows to the side of the screen and get them covering one half. However, I never use the similar feature that allows dragging a window to the top, and it often …

I tried to get back to an IRC interface to Slack using Matrix, and it had some problems. Thanks to Colin Watson’s comment on that post, I tried Daniel Beer’s slirc, and so far it seems to be working pretty well. Here’s what I did: Get a Slack legacy to…

Update: I found a better solution using slirc. I like using HexChat to talk to my colleagues, like one other guy. It is fast, and it pops up a new window when someone sends me a direct/private message. Recently, Slack shut down their IRC gateway, forci…

Groovy has lots of interesting syntax that can be used for domain-specific languages, such as Gradle build files, and Jenkinsfiles. I try to demystify the syntax tricks a bit so you have a chance to read and understand what the code is actually doing: …

I have 2 tables like this: > SELECT * FROM table_a; +——+——+ | id | name | +——+——+ | 1 | row1 | | 2 | row2 | +——+——+ > SELECT * FROM table_b; +——+——+——+ | id | name | aid | +——+——+——+ | …

If, like me, you are this person: (Source: xkcd.com/1782) You may want to fix the stupid :slightly_smiling_face: messages you receive from Slack via the IRC gateway. Obviously, I’d prefer they went away entirely, but it’s still better to see a characte…

I am trying to practice documentation-driven development in Pepper3, so every time I start on an area, I will write documentation explaining how it works, and include examples that are automatically verified during the build. I’ve started work on lexin…

Today I wanted to fix a Git repo that contained some bad commits (i.e. git fsck complained about them). [I wanted to do this because GitLab was not allowing me to push the bad commits.] I wanted the code to look exactly as it did before, but the histor…

Series: Examples, Questions My last post Examples of Pepper3 code was a reply to my friend’s email asking what it was all about. They replied with some questions, and I thought the questions and answers might shed some more light: Questions! Brillian…

Series: Examples, Questions I have restarted my effort to make a new programming language that fits the way I like things. I haven’t pushed any code yet, but I have made a lot of progress in my head to understand what I want. Here are some random examp…

Stop! This blog post is out of date – see Recording gameplay videos on RetroPie for a live version in github that may be more helpful. Credits: this is a slightly corrected and shortened version of How To Record A GamePlay Video From A RetroPie by sels…

My OpenMarket colleagues and I ran a workshop at TECH(K)NOW Day on how to write your own programming language: A big thank you to my colleagues from OpenMarket who volunteered to help: Rowan, Jenny, Zach, James and Elliot. An extra thank you to Zach …

Today I found I could not connect out through my proxy server with FileZilla It stopped working when I changed my password to something containing a double quote “. The solution? Change to use WinSCP.

I have been working on a prototype level editor for Rabbit Escape, and I’ve had trouble getting the layout I wanted: a toolbar at the side or top of the screen, and the rest a zoomable workspace. Something like this is very common in many desktop appli…

Today I was trying to make a simple tarball of a project + its dependent jar using the maven-assembly-plugin. I know this is a terrible way to do anything, but hey, just in case someone else wants to do something just as terrible, here are my pom.xml a…

I used to run Planet Code using Venus but that started breaking recently with 500 errors for SNI-enabled sites, and it looks very unmaintained. I considered some other static aggregators, but on shared hosting it’s hard to get the right Ruby version an…

If you want “tomorrow” in Python datetimes, don’t construct a datetime like this: from datetime import datetime, timedelta td = datetime.today() tm1 = datetime(td.year, td.month, td.day + 1, 14, 0, 0) # Don’t do this! Because it will work sometimes, b…

Today at the Egham Raspberry Pi Jam we did two things: 1. The Broken Levels Challenge Some nasty person came and broke our levels for our game Rabbit Escape and we need you to fix them! To play this game you will need a PC version of Rabbit Escape, ou…

On Wednesday 28th June 2017 a group of people from OpenMarket went to the Fora office space in Clerkenwell, London to run a workshop with the Women Who Code group, who work to help women achieve their career goals. OpenMarket provided the workshop “Wri…

For my attempt to improve the asyncio.as_completed Python standard library function I needed to build a local copy of cpython (the Python interpreter). To test it, I needed the aiohttp module, which is not part of the standard library, so the easiest w…

Series: asyncio basics, large numbers in parallel, parallel HTTP requests, adding to stdlib In the previous post I demonstrated how the limited_as_completed method allows us to run a very large number of tasks using concurrency, but limiting the number…