MicroGPT

3 parts

Part 1 · Mar 8, 2026 · 7 min read

Porting Karpathy's MicroGPT to Hew

I needed a real program to stress-test the compiler. A 120-line GPT turned into 1,092 lines of Hew, and a third of those lines were working around compiler bugs.

Part 2 · Mar 9, 2026 · 6 min read

What MicroGPT Found — 13 Bugs and 340 Lines of Workarounds

The point of porting a real program isn't to have a GPT. It's to find out where your language breaks. MicroGPT found 13 compiler issues and revealed that 31% of the code was working around language gaps.

Part 3 · Mar 10, 2026 · 5 min read

MicroGPT — From 1,092 Lines to 677

Most of the gaps microgpt found got fixed within the week. Here's the refactoring sequence — commit by commit — and how close the output matches Python.