Simon WillisonModify

2025-07-02 12:35:35

Mandelbrot in x86 assembly by Claude

I prompted Claude Sonnet 4:

Write me an ascii art mandelbrot fractal generator in x86 assembly

And got back code that looked... like assembly code I guess?

So I copied some jargon out of that response and asked:

I have some code written for x86-64 assembly using NASM syntax, targeting Linux (using system calls for output).

How can I run that on my Mac?

That gave me a Dockerfile.

I tried running it on my Mac and... it failed to compile.

So I fired up Claude Code (with the --dangerously-skip-permissions option) in that directory and told it what to run:

Run this: docker build -t myasm .

It started crunching. It read the errors, inspected the assembly code, made changes, tried running it again in a loop, added more comments...

...and eventually produced an ASCII art image of a fractal! Claude Code proudly declared:

Success! The Docker container ran and generated a Mandelbrot set visualization using ASCII characters. The output shows all @ symbols, which indicates the algorithm is working but all points are inside the set (high iteration count). The program compiled and executed successfully on x86_64 architecture via emulation.

Yeah... I was not satisfied with an image that was entirely @ symbols! I said:

That is a bad result - it is just @ signs, I cannot see the fractal

Claude made a few more changes and gave me the result I wanted:

Here's the finished assembly code, the Dockerfile to run it on a Mac and the full transcript of the Claude Code session that got it there.

Tags: mandelbrot, ai, generative-ai, llms, ai-assisted-programming, anthropic, claude, vibe-coding, claude-code

2025-07-02 07:55:09

TIL: Using Playwright MCP with Claude Code

It turns out it's easy:

claude mcp add playwright npx '@playwright/mcp@latest'
claude

The claude mcp add command only affects the current directory by default - it gets persisted in the ~/.claude.json file.

Now Claude can use Playwright to automate a Chrome browser! Tell it to "Use playwright mcp to open a browser to example.com" and watch it go - it can navigate pages, submit forms, execute custom JavaScript and take screenshots to feed back into the LLM.

The browser window stays visible which means you can interact with it too, including signing into websites so Claude can act on your behalf.

Tags: armin-ronacher, til, playwright, ai-assisted-programming, anthropic, claude, claude-code

2025-07-02 05:46:20

One of the best examples of LLM developer tooling I've heard is from a team that supports software from the 80s-90s. Their only source of documentation is video interviews with retired employees. So they feed them into transcription software and get summarized searchable notes out the other end.

— Kevin Webb, a couple million lines of Smalltalk

Tags: small, ai-assisted-programming, ai, llms

2025-07-02 04:37:43

Sometimes a service with a free plan will decide to stop supporting it. I understand why this happens, but I'm often disappointed at the treatment of existing user's data. It's easy to imagine users forgetting about their old accounts, missing the relevant emails and then discovering too late that their data is gone.

Inspired by today's news about PlanetScale PostgreSQL I signed into PlanetScale and found I had a long-forgotten trial account there with a three-year-old database on their free tier. That free tier was retired in March 2024.

Here's the screen that greeted me in their control panel:

What a great way to handle retiring a free plan! My data is still there, and I have the option to spin up a database for 24 hours to help get it back out again.

Tags: saas, databases

2025-07-02 03:57:46

Using LLMs for code archaeology is pretty fun.

I stumbled across this blog entry from 2003 today, in which I had gotten briefly excited about ColdFusion and implemented an experimental PHP template engine that used XML tags to achieve a similar effect:

<h1>%title%</h1>
<sql id="recent">
select title
from entries 
order by added desc
limit 0, %limit%
</sql>
<ul>
  <output sql="recent">
    <li>%title%</li>
  </output>
</ul>

I'd completely forgotten about this, and in scanning through the PHP it looked like it had extra features that I hadn't described in the post.

So... I fed my 22 year old TemplateParser.class.php file into Claude and prompted:

Write detailed markdown documentation for this template language

Here's the resulting documentation. It's pretty good, but the highlight was the Claude transcript which concluded:

This appears to be a custom template system from the mid-2000s era, designed to separate presentation logic from PHP code while maintaining database connectivity for dynamic content generation.

Mid-2000s era indeed!

Tags: claude, coldfusion, ai, llms, ai-assisted-programming, php, generative-ai, projects

2025-07-02 02:16:12

Announcing PlanetScale for Postgres

Today PlanetScale are announcing a private preview of their new horizontally sharded PostgreSQL solution, due to "overwhelming" demand.

Notably, it doesn't use Vitess under the hood:

Vitess is one of PlanetScale’s greatest strengths [...] We have made explicit sharding accessible to hundreds of thousands of users and it is time to bring this power to Postgres. We will not however be using Vitess to do this.

Vitess’ achievements are enabled by leveraging MySQL’s strengths and engineering around its weaknesses. To achieve Vitess’ power for Postgres we are architecting from first principles.

Meanwhile, on June 10th Supabase announced that they had hired Vitess co-creator Sugu Sougoumarane to help them build "Multigres: Vitess for Postgres". Sugu said:

For some time, I've been considering a Vitess adaptation for Postgres, and this feeling had been gradually intensifying. The recent explosion in the popularity of Postgres has fueled this into a full-blown obsession. [...]

The project to address this problem must begin now, and I'm convinced that Vitess provides the most promising foundation.

I remember when MySQL was an order of magnitude more popular than PostgreSQL, and Heroku's decision to only offer PostgreSQL back in 2007 was a surprising move. The vibes have certainly shifted.

Tags: databases, mysql, postgresql, scaling, sharding, vitess