Blog
Stories, insights, and lessons from building Elo
Guards, Checks, and Data Wrangling
New runtime validation primitives and improved data extraction make Elo more expressive for real-world data pipelines.
Elo 0.9.x is here!
First official version is released. Discover here how Claude Code and I designed and wrote Elo in seven days, and what made it possible.
Days Six and Seven: Teaching and Typing
The final days of 2025 brought two major additions: interactive exercises for learning Elo, and a powerful type definition system inspired by Finitio.
Day Five: Security and Polish
A language that compiles to executable code needs security guarantees. Day five added formal security documentation, bug bounty program, and deep equality—the kind of polish that separates toys from tools.
Day Four: Words Matter
Naming things is one of the hardest problems in computer science. Day four was about getting the vocabulary right—and restricting the grammar to prevent future confusion.
Day Three: Data Structures and a New Home
Day three brought the biggest transformation yet: Elo learned to handle data, gained a proper website, and introduced AI agents that audit their own code.
Day Two: The Art of Refinement
Day one was about building something from nothing. Day two was different—it was about refinement, rebranding, and preparing Elo for the world.
Building Elo: A Human-AI Collaboration Story
Elo was built in a single day through an intense collaboration between a human developer and Claude Code. Here's what we learned about making AI pair programming actually work.