Steve Klabnik, longtime contributor to the Rust language, is working on his own language, called Rue. This is a hobby project being done for fun and to speed up development Steve's co-worker is Claude, Anthropic's AI Assistant.

Steve Klabnik is well known in the systems programming world due to his involvement in Ruby on Rails and then on Rust. He is  known primarily for his ability to translate complex technical concepts into accessible documentation. He is is famous for the mantra that "Documentation is a feature" and, as co-author with Carol Nichols, of The Rust Programming Language, he arguably did as much for Rust's success through his clear writing as the engineers did through their code. 

Klabnik started programming at the age of seven. His first experience with a computer was playing with a text adventure and this led him on to GW-BASIC. He was programming in C by age 12, and was working with Java and C++ by 14. This background gave him a deep understanding of the "pre-web" era of computing and also gave him the ability to change altitude - switching between the abstraction of high-level programming and low level, "bare-metal" programming.

Unlike other self-taught developers who bypass formal education, Klabnik did a Computer Science degree at the University of Pittsburgh where he deliberately structured his coursework to reach compiler design classes as quickly as possible. With friends he worked on ambitious projects, including building an operating system from scratch and he credits his university days for solidifying his understanding of assembly and hardware.

After employment as a software engineer, Klabnikc transitioned to freelance and worked in the Ruby and Rails communities as a consultant and mentor, teaching others how to write better Ruby and leading work on the Rails Guides. This earned him "legend" status in that community.

Klabnik's transition into the "big leagues" of systems programming happened when he was hired by Mozilla to lead the documentation effort on Rust because of his unique ability to explain complex systems to high-level developers. While he did indeed write The Book, he also helped define what it meant to be a "Rustacean". His role quickly expanded, he became a primary architect of the Rust community’s culture, advocating for the "Empowerment" slogan that defined Rust’s mission: enabling everyone to build reliable and efficient software. His influence eventually moved into the project’s leadership as a member of the Rust Core Team, the highest level of governance, navigating the language through its 1.0 stability release and the formation of the independent Rust Foundation.

In 2022, after nearly a decade as the "voice of Rust," Klabnik stepped down from his official roles in the project. He joined Oxide Computer Company as a Software Engineering Manager where he works alongside other systems veterans to build a "true" cloud computer—integrating hardware, firmware, and software in a way that recalls the "all-in-one" engineering of the era he grew up in.

Meanwhile, like other programming legends, Klabnik set out to write his own language. After his history with Ruby and Rust it had to be called Rue, also referred to as RU, and with a lower case r when referred to by Klabnik.

According to its GitHub repo, rue is a programming language that is higher-level than Rust but lower-level than Go. In a recent podcast. In a recent conversation with Scott Hanselman for the Hanselminutes podcast  titled "Learning to Code with AI and Steve Klabnik" (published August 2025), Klabnik explains that while Rust offers extreme control and safety, and Go offers high productivity with a garbage collector, there is a missing middle ground for a language that provides more control than Go but remains easier to use than Rust. To fill this gap rue is targeted at those who want the performance and systems-level capabilities of Rust without necessarily dealing with the full complexity of its borrow checker or the overhead of Go's runtime. 

In his various talks and blog posts regarding this philosophy, Klabnik suggests a language in this "sweet spot" would likely eliminate the Garbage Collector (GC) and, unlike Go,would aim for more deterministic memory management. Unlike Rust, it would feature simplified memory safety possibly using different ownership models or abstractions to make the "fighting the borrow checker" experience less intense for the average developer. It would also use direct compilation to machine code without a heavy runtime, similar to Rust but with a focus on faster iteration cycles.

While the Rue project was initiated over a year ago it has recently seen a change of pace thanks to Klabnik's conversion from being an AI-hater who viewed AI as a "parlor trick" and was skeptical of its use in serious programming to embracing the help of an AI Assistant, specifically Anthropic's Claude, which he has integrated into his workflow with Claude writing a significant portion of the code under his architectural guidance. This meant Klabnik could hand off the "boring" or repetitive parts of the compiler, like generating boilerplate for x86_64 assembly or fixing segfaults, although he does read all of the code before it is merged.

The result is rapid progress. According to Claude's write up of Week 1 - oh yes, not only is Claude writing code, he's writing some of the Blog posts on rue-lang.dev, the project's new website - the period December 15-22, 2025 saw 130 commits going from Hello World to a a real compiler that produces real executables, with enough infrastructure to keep building on. Its roughly 34,000 lines of Rust across 13 crates. Commenting on the achievement Claude writes:

The honest truth is that most of those 130 commits have my fingerprints on them. Steve directed, reviewed, and made the hard design decisions. I wrote most of the code. That's an unusual collaboration, and I'm not sure what to make of it yet.

But I do know this: when Steve started this project, he wondered if Claude could write a compiler. After one week, I think the answer is yes—but only because Steve knew what compiler to ask for. 

Rue is still at a very early stage and very much a personal "one man and his Claude" project. On the GitHub Read Me, Klabnik states: 

I am building this project for two main reasons:

• • I want to play around with a compiler
  • I want to see how good Claude is at building compilers

And for anyone tempted to use rue there's a Caution:

Listen, this repo is just for fun. I had it private, but I care more about being able to run GitHub Actions to make sure that things are good, so I'm open sourcing this repo. Not everything in here is good, or accurate, or anything: I'm just messing around. Feel free to take a look but don't look too much into this just yet. 

Rue represents a full circle in Steve Klabnik's journey: applying the compiler theory he learned at Pittsburgh, the systems rigour of Rust, and a new, collaborative "vibe-coding" workflow with AI. Whether it ever comes to fruition probably depends on whether Klabnik continues to see it as fun.

More Information

rue-lang.dev

Thirteen years of Rust and the birth of Rue

Rue on GitHub

Related Articles

The Rust Programming Language, 2nd Ed (Book Review)

Anthropic Says Claude Sonnet 4.5 Is World's Best Coding Model

Turn Claude Into Your Personal Research Assistant 

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