Chelis

Chelis is an open-source numerical computing language for code that agents write and people supervise. Tensors carry named dimensions and precision in their types, and a compiler and proof stack check shapes, precision, effects and ownership before the program runs. The project is hosted by the Chelis-Lang organization, and the site lists release 0.19.1 for Linux x86_64 and macOS arm64 under the MIT license.

What It Is

Chelis is a programming language and toolchain for numerical work such as pricing, time series and statistics. Its aim is that an agent's mistake becomes a compiler error rather than a plausible wrong number. For example, a NumPy-style broadcast that silently stretches a 3 by 1 array against three weights is rejected by chelis check before anything executes.

The readable syntax is called Surf (.ch), and Deep (.dp) is the canonical form used by the compiler and agents. Programs build to native code through C.

How the Agent Loop Works

The CLI is designed to sit inside an agent's write-check-fix loop. chelis check answers in JSON with the error kind and source span, and the same input always produces the same answer. The agent repairs the code until no errors remain, then chelis prove checks properties declared with @property using type checking, an SMT solver or seeded sampling. Each result names the method behind it. A person then reviews types and properties rather than every line.

chelis tide mcp exposes check, eval, prove and structural edit operations as MCP tools. A SKILL.md and llms.txt are published for coding agents.

What the Compiler Enforces

• Shapes must match; nothing is broadcast implicitly.
• Named dimensions match by name, so batch is not seq even when both are the same size.
• f32 and f64 meet only through an explicit cast.
• Random operations require an explicit key.
• Borrowed values cannot be passed to owned parameters without a copy.
• Negative indices stop the program instead of wrapping around.
• I/O appears in a function's effects.

Shells and Packages

Shells installed with Reef extend the core language: Nautilus for numerical methods, statistics and optimization, Coral for typed dataframes, Shoals for quantitative finance, and economoist for economic models with properties checked by an SMT solver. The research page mentions chelis prove with cvc5 and a first-order core calculus mechanized in Lean 4. Commercial support is listed from C Proof.

Setup Path

The toolchain manager chelisup is installed from a script attached to each release, then downloads the compiler and keeps versions side by side. chelis build needs a native C compiler on the platform. Documentation includes the Chelis book, a first-program lesson, CLI workflow and agent workflow guides.