Spec-first publication
Language specification, design decisions, and governance record live now under CC BY 4.0. Compiler source and binary follow in a later complete-release phase under FSL-1.1-Apache-2.0.
The language AI writes
The language AI writes — compile-time safety for AI-authored automation.
Arcana Lang is a programming language designed as a compile-time-safe target for AI code generation. Generic languages — TypeScript, Python, Ruby — were designed for humans. AI generators that target them inherit every safety problem those languages permit. Arcana inverts the premise: if an AI generates code that would violate a declared safety constraint, the compiler rejects it before the code can run.
This site is the public language specification, design decisions, and governance record. Designed, governed, and maintained by Micah Hurst ([email protected]).
The six pillars
Section titled “The six pillars” Compile-Time Safety The irreducible core — effect system, affine resource types, refinement types, and scoped data-flow analysis.
Effect Contracts & Capability Discipline Effects as operational contracts that travel from authoring through checking to deployment.
Batteries-Included, Closed-World by Design First-class capabilities under a closed-world model — simultaneously a productivity and supply-chain-safety property.
Portable Runtime & Execution WebAssembly + sandboxed runtime + multi-target codegen. A runtime-side complement to the compile-time guarantees.
Self-Hosting & Determinism A journey, stated honestly. Stage1=stage2 self-hosted; verification-harness migration is the in-progress piece.
Governance & Honest Scope The trust mechanisms — non-promises, current honest state, open intentions, and a public marketing-claims ledger.
Start here
Section titled “Start here”If you’re new to Arcana, read these three pages in order. They give you the framing, the orientation, and the first concrete demonstration. Then you can decide which pillar to dig into.
1. How to read Arcana code The samples on this site default to S-expressions, not Rust-shaped prose. Learn the two-layer architecture (canonical + human view) and how to use the toggle. ~3 minutes.
2. We didn't build a language for humans to write The framing essay. Why design a language FOR AI generators rather than try to make generators better at the languages we already had. ~8 minutes.
3. Pillar — Batteries-Included The most accessible pillar. First-class effect capabilities, schema-as-types, the closed-world stdlib. Start your tour of the technical pillars here. ~10 minutes.
Hit an unfamiliar term? Glossary defines every Arcana-specific token used on this site in one line each.
Sizing up a project?
Section titled “Sizing up a project?” When to use Arcana What Arcana is a strong fit for, and what it deliberately isn't — with a one-line decision rule for AI agents and humans choosing a stack.
Cookbook — coming soon A worked-example collection is on the way. It's gated on the canonical-projection tooling so every recipe ships with verified canonical, not hand-guessed forms.
Recent writing
Section titled “Recent writing” I set out to build websites. I ended up designing a language for AI. The origin story — how building software for small businesses led to Arcana, and why the wall I hit was the language, not the AI.
We didn't build a language for humans to write Arcana Lang is a target for AI code generation, not a human-coding tool. What changes when you design FOR the generator.
Four decay modes Arcana cannot solve at the language layer How safety gates fail over time. Extends Jason Iannazzo's Equifax/Target framework with two AI-era additions.
About this publication
Section titled “About this publication”Adoption model
Closer to WebAssembly or LLVM IR than to Rust or Python: code is generated into Arcana by AI systems and reviewed by humans, rather than hand-written by a developer community.
Honest scope
Arcana’s safety claims are deliberately hedged today — qualifying their scope, their gaps, and where they don’t apply. The hedges stay until a formal external security review independently confirms broader claims are defensible.
A seventh, future-only pillar
A Curated-Ecosystem-Future pillar is part of the long-term identity but explicitly out of the launch set — surfaced under Open Intentions (Not Commitments) rather than as a current capability.
Stay in the loop
Section titled “Stay in the loop”The compiler binary isn’t public yet — the spec, decisions, and governance are. If you want a single heads-up when the spec opens further or the compiler goes public, leave an email. No tracking, no list-sharing.