Ertu's Blog

Clojure is almost as fast as C (with some help)

Thu, 11 Jun 2026 18:53:00 +0300

I have a stress test written in C: 100,000 cubes flying around in space. The CPU rebuilds every cube’s 4x4 transform matrix on every frame and sends all of them to the GPU. That is around 900,000 sine evaluations and 6 MB of matrix data per frame, and after that the GPU still has to draw 3.6 million triangles. So the frame is half CPU work, half GPU work.

I ported it to Clojure and wanted to see how close I could get to the C version’s FPS. I should say up front that I did not do the optimization work alone: I paired with Claude Code on it, and most of the digging in this post (the benchmarks, the JIT logs, the failed attempts) comes from that session.

AI is killing our online interaction

Mon, 22 Dec 2025 17:23:52 +0300

Every new era brings its own set of pros and cons. Sometimes the balance between them really matters. What I want to talk about here is one of the discouraging effects AI has on us engineers today.

AI has brought major changes. With AI editors, we can finish boring tasks very quickly. Even people who do not know how to code can now show impressive demos online through vibe coding. This is all great. Everything is faster and more accessible. On paper, it feels like we have already won. But what have we lost?

A snapshot from the Walkman era

Thu, 26 Jun 2025 12:26:38 +0300

Sometimes, in the middle of life, out of nowhere, random snapshots from the past pop into our minds. It could happen while walking, reading a book, or watching a view. For me, it usually happens when I’m coding or looking at a landscape. This time, while I was coding, a snapshot from more than 20 years ago came to mind.

I was a kid, maybe around ten. We had a music CD at home. This was the late ’90s or early 2000s, so we used Sony Walkmans to listen to music. I really liked that CD back then, but I couldn’t remember its name or the cover clearly, just some blurry fragments. A few words stuck in my mind: “Webb” and “Ocean.” These two were clear. I immediately started searching online, hoping to find a digital version. But the deeper I looked, the more surprising the result was: absolutely nothing. It was like the internet had forgotten it. Search engines only showed recent, popular content. It felt like they had erased the past.

I made a multiplayer shooter game in Lisp

Wed, 22 Jan 2025 11:43:38 +0300

Developing a multiplayer third-person shooter game as a solo developer is a journey filled with challenges and rewards. I embarked on this adventure to create Wizard Masters, a web-based multiplayer game where players battle as mages wielding elemental spells.

Built using Clojure, a Lisp dialect, this project pushed the boundaries of web game development and my own skills as a programmer. Here’s how it went.

In Wizard Masters, players can choose from six elemental spells—fire, toxic, ice, lightning, and earth—and compete in two modes: solo and team deathmatch. I published the game on CrazyGames to reach a broader audience. However, its multiplayer nature demanded a large player base, which was a constant challenge.