GitHub - Chelis-Lang/chelis: Turtles all the way down

Chelis is a numerical computing language for code that agents write and people supervise. Tensors carry named dimensions and precision in their type, and a proof stack checks the properties you state.

def portfolio_return(w: tensor[3, f64], r: tensor[3, 1, f64]) -> tensor[f64] = {
  weighted = mul(w, r)
  weighted |> sum(0)
}

In numpy, returns shaped 3 by 1 stretch against three weights into a 3 by 3 grid and the sum comes back as a plausible wrong number. chelis check rejects the same multiply before anything runs. The error from its JSON report:

{"kind":"DimensionMismatch","message":"`mul` argument 2: expected rank-1 tensor, got rank-2 tensor","severity":0.8,"expected":"rank-1 tensor","got":"rank-2 tensor","span":{"span":"point","offset":94},"span_id":"surf:94..103"}

Checked before it runs. The compiler checks shapes, precision, effects, and ownership. Dimensions match by name, f32 and f64 do not mix without a cast, I/O appears in a function's effects, and random operations take explicit keys.
An agent in the loop. chelis check answers in JSON with the error kind and source span, and the same input always gets the same answer. chelis tide mcp gives an agent check, eval, prove, and structural edits as MCP tools.
Properties you can review. chelis prove checks @property declarations with type checking, an SMT solver, or seeded sampling, and each result names the method behind it. A second checker written in Chelis cross-checks the compiler, and a core calculus of Chelis is mechanized in Lean 4.
General-purpose numerics. Surf (.ch) is the readable syntax; Deep (.dp) is the canonical form the compiler and agents use. Programs build to C. Shells, installed with Reef, cover numerical methods (Nautilus), dataframes (Coral), and quantitative finance (Shoals).

Install

Chelis is distributed as prebuilt binaries for Linux x86_64 and macOS arm64, published on the releases page. The install guide has the steps and the native C compiler chelis build needs on each platform.

Documentation

The Chelis guide covers the first program, the CLI, types, effects, properties, and Reef packages. The same guide is the mdBook in docs/book, rendered from chelis.ch; build it locally with mdbook build docs/book. The examples directory holds executable Chelis programs.

License

MIT