In early November 2025, Anthropic had a program giving out $250 credits for Claude Code on the web. It expired on November 18, and on November 15 I still had $220 left.

I was working on something else and as a side effect accidently vibe coded a prolog interpretor on my phone over the weekend.

I haven't used Prolog for 20 years, and but it does seem to be roughly correct.

This project is to see how far I can push it. 🚀

Did I really ask Codex to add more Emojis to this README? Yes I did...

> uv run main.py ./examples/examples.pl  -q "mammal(X)" -v

Loading program from './examples/examples.pl'...
Successfully loaded './examples/examples.pl'
Query: mammal(X).
Solution 1:
X = dog

Solution 2:
X = cat

> uv run main.py ./examples/examples.pl  -q "grandparent('tom', Y)" -v
Loading program from './examples/examples.pl'...
Successfully loaded './examples/examples.pl'
Query: grandparent('tom', Y).
Solution 1:
Y = ann

Solution 2:
Y = pat

• No human written code. Can prompt things, can tell tools what changes to make but no human written code should be used.
• Don't deliberatly add slop. If you notice it doing something wrong, get it fixed.
• Use all the tools you can. Add lots of tests! Add automatic code reviews! Add security audits!

• Don't settle on average code. If an AI is generating slop, tell it what is wrong and how to improve it.

• This is a fun project! Don't take it too seriously.

• I don't know if this works at all. It seems to work, and there are some tests that work but that's it.
• I'm putting it under a MIT license but as AI written code it isn't clear if it can be copyrighted at all
• There are lots of real Prolog implementations that are probably better than this! Use them.

YES!

Please send in your vibe contributions! Just open a PR.

Are you a tool vendor who wants your tools used? Yes! I'd love to use them. I prefer a PR but opening an Issue also works