# GPT-6-Luna and Specs > Source: > Published: 2026-10-10 07:00:00+00:00 This is probably not going to shock anyone, but I **generated** some more **Rust code** with **GPT-6-Luna** today. I had a Rust function (well 2 functions) that was around **80 lines** of code. I decided to write a spec for it, and then sent it to GPT-6-Luna for code generation. GPT-6-Luna responded with a **new function**, and one that was only **30 lines** of code. • I reviewed the function; it seems GPT used early returns, which reduced at least one branch, and combined both functions into one. • I tested it and it worked correctly. • I would not be surprised if it was faster than my old code too, due to having one fewer branch. It seems to me that **spec-driven development** may become a more prominent part of software development. It is likely the **spec** will become **more important** than the code. In any case, Luna did the code gen in 21 seconds for only $0.0011—it seems like a good model to do simpler code generations with.