When dealing with colour spaces, one eventually encounters the XYZ colour space. It is a mathematical model that maps any visible colour into a triple of X, Y and Z coordinates. Defined in 1931, it's nearly a century old and serves as a foundation upon which other colour spaces are built. However, XYZ has one aspect that can easily confuse programmers.

You implement a conversion function and, to check it, compare its results with an existing implementation. You search for an online converter, only to realise that the coordinates you obtain differ by two orders of magnitude. Do not despair! If the ratio is exactly 1:100, your implementation is probably correct.

This is because the XYZ colour space can use an arbitrary scale. For example, the Y component corresponds to colour’s luminance but nothing specifies whether the maximum is 1, 100 or another value. I typically use 1, such that the D65 illuminant (i.e. sRGB’s white colour) has coordinates (0.95, 1, 1.089), but a different implementation could report them as (95, 100, 108.9). (Notice that all components are scaled by the same factor).

This is similar to sRGB. In 24-bit True Colour representation, each component is an integer in the 0–255 range. However, a 15-bit High Colour uses the 0–31 range, Rec. 709 uses the 16–235 range and high-depth standards might use the 0–1023 range.

A closely related colour space is xyY. Its Y coordinate is the same as in XYZ and can scale arbitrarily, but x and y have well-defined ranges. They define chromaticity, i.e. hue, and can be calculated using the following formulæ: x = X / (X + Y + Z) and y = Y / (X + Y + Z). Both fall within the [0, 1) range.

Four years ago I proclaimed that regular expressions were broken. Two years ago I discussed this with BurntSushi and even though his expertise in the subject could not be denied, he did not manage to change my opinion. But now, two more years after that, I adjusted my stance.

Everything factual I’ve written previously is still accurate, but calling regular expressions broken might have been a bit too much of a hyperbole. There’s definitely something funky going on with regex engines but I’ve realised an analogy which makes it make sense.

Implementing Solana IBC bridge, I had to deal with various constraints of the Solana protocol. Connecting Solana to Composable Foundation’s Picasso network, I needed to develop an on-chain light client capable of validating Tendermint blocks. This meant being able to validate 50 signatures in a single transaction.

Turns out that’s not possible on Solana and it’s not exactly because of the execution time limit. The real culprit is the transaction size limit which I’ve discussed previously. This article describes how signature verification is done on Solana, the limit on the number of signatures that can be verified in a single transaction and how that limit can be worked around.

Solana transactions are limited to 1232 bytes which was too restrictive when I was implementing Solana IBC bridge while working at Composable Foundation. The smart contract had to be able to ingest signed Tendermint block headers which were a few kilobytes in size.

To overcome this obstacle, I’ve used what I came to call chunking. By sending the instruction data in multiple transactions (similarly to the way Solana programs are deployed), the Solana IBC smart contract is capable of working on arbitrarily-large instructions. This article describes how this process works and how to incorporate it with other smart contracts (including those using the Anchor framework).

In September 2022, ‘Théâtre D’opéra Spatial’, a work submitted by Jason Allen, won Colorado State Fair’s annual fine art competition in the digital art category. What made the success noteworthy was that the image had been AI-generated. Mr Allen eventually tried to register the work with the US Copyright Office but his attempts turned out fruitless. In September 2023 the Office refused his registration.

I didn’t think much of it at the time. I wasn’t that invested in the consideration of what kind of ‘two-dimensional artworks’ are protected by copyright and, more notably, I somewhat agreed with the decision. Perhaps the prompt was protected, but if only minor manual edits were made to the image, it felt like a stretch to say the image as a whole could be covered by copyright law.

* available in Rust nightly.

There are several aspects of Rust that I’m not particularly fond of but the one that takes the cake is core::io::BorrowedBuf which I despise with passion. It’s a nightly feature which puts in question my extreme emotions about it. On the other hand it means there’s time to stop it from getting stabilised and figure out something better.

In this article I’ll describe the problem the feature addresses, the issues I have with the solution and describe some alternatives. As it turns out, things aren’t as easy as they seem on the first look.

In 2023 UniSuper, an Australian retirement fund, decided to migrate part of its operations to Google Cloud. As port of the migration, they needed to create virtual machines provisioned with limits higher than what Google’s user interface allowed to set. To achieve their goals, UniSuper contacted Google support. Having access to internal tools, Google engineer was able to create requested instances.

Fast forward to May 2024. UniSuper members lose access to their accounts. The fund blames Google. Some people are sceptical, but eventually UniSuper and Google Cloud publish a joint statement which points at ‘a misconfiguration during provisioning’ as cause of the outage. Later, a postmortem of the incident sheds even more light on events which have transpired.

Turns out that back in 2023, Google engineer used a command line tool to manually create cloud instances according to UniSuper’s requirements. Among various options, said tool had a switch setting cloud instance’s term. The engineer omitted it leading to the instance being created with a fixed term which triggered automatic deletion a year later.

So, human error. Scold the engineer and case closed. Or is it?

So far I have been lucky in my professional life. I have never had any conflicts with my employers and for the most part maintained good rapport with coworkers and managers alike. Alas, my luck has finally run out.

Long story short, I left Composable Foundation in October and I am still waiting for my final paycheck. TL;DR: If you are doing business with them make sure you are paid in advance.

cd is a straightforward command. As per the name, it changes the directory and does its job perfectly well. But what if it could do more? One scenario is wanting to execute a command inside a specific location without affecting the current working directory (CWD). This article introduces a cd replacement which offers that feature as well as provides more ways to specify the target directory.

It is important to note that it’s not intended for scripting. Rather, it’s only meant for interactive use where it streamlines some operations.

Some people struggle to understand the distinctions between ‘free software’ and ‘open source software.’ Let’s clear up the confusion with an analogy.

Imagine a world without vegetarianism. One day, someone proposes a new diet called ‘moral eating,’ which excludes meat for ethical reasons. Some people embrace it, and discover additional benefits like reduced environmental impact. However, advocates observe that implying people not adhering to the diet are immoral isn’t the best recruitment strategy. They coin the term ‘sustainable eating’ to focus on the environmental advantages.

But now people get bogged down in philosophical debates. If one uses the term ‘moral eating’ some assume they don’t care about the environment; on the other hand, if one says ‘sustainable eating’ some assume they don’t care about animals. To avoid this an all-encompassing acronym MSE (Moral and Sustainable Eating) is created. It signifies the same thing — no meat — but avoids getting entangled in justifications.

And so we end up with three distinct terms — moral eating, sustainable eating and MSE — which all refer to the same diat. What we call vegetarianism.