This is the second "I built a programming language" post in a day, and if I post the one I'm building, we can have a three-day streak :D They thought AI meant personal software, but it also means personal programming languages!

In all seriousness, this is great, and why not? As the post said, what once took months now takes weeks. You can experiment and see what works. For me, I started off building a web/API framework with certain correctness built in, and kept hitting the same wall: the guarantees I wanted (structured error handling, API contracts, making invalid states unrepresentable) really belonged at the language level, not bolted onto a framework. A few Claude Code sessions later, I had a spec, then a tree-sitter implementation, then a VM/JIT... something that, given my sandwich-generation-ness, I never would have done a few months ago.

I should post number 4, last week I built a new lisp framework for LLMs as first class programmers. It compiles for go, python, and JS.