Well I need to check out the competition for my livelihood.

I thought I'd see what $2-3 buys me on Codex. I got all of:

* a compiler for a numerical bc-like language with an LLVM back end

* a small test suite (not good enough to catch everything it should have)

* a terminal based IDE for it with separate editor, syntax coloring and output panel - like Compiler Explorer. It'll show the LLVM IR too. Surprised to see it handles things like window resizes without me asking.

* example code including a simple 1D Poisson solver and an MLP trained by backpropagation.

It compiles fast enough, and generates fast enough code, that it has the interactivity of a spreadsheet so I can do things like explore tweaks to that MLP learning rate in "real time".

I tried to add multidimensional arrays. I burnt $3 having it fail - probably because it was writing array indexing code directly for LLVM whereas I would have written that in C and incorporated whatever IR clang generated. It was able to give excuses though.

For a few dollars more I added minor features at which point the total cost of writing N lines of code was probably growing quadratically in N and I called it quits at $9.

A lot more useful than the subject of this story
https://www.theregister.com/2026/02/09/claude_opus_46_compiler/

Worth noting that billing lags usage a bit so you need to set spending limits!