With.

The thesis.

With is a systems language whose safety model is Rust-like in outcome and different in mechanism. Ownership is persistent and single; borrowing is ephemeral and never stored; relationships that must outlive a scope are expressed as typed handles. That trade removes lifetime annotations from the language at the cost of forbidding references inside long-lived data structures. The compiler is written in With and rebuilds itself to a byte-identical fixpoint.

It is designed for agents and humans to author alike. The rule that removes ceremony for a human, that no character the program already determines has to be written, applies equally to an agent generating the code, and the explicit spellings that remain sit where an author of either kind is most likely to be silently wrong. with init gives every new project an agent primer.

If the creators of the language can leak by accident, the design is wrong, not the programmer.

What it looks like.

fn handle(req: Request) -> Response:
    let user = db.find_user(req.params.id) else:
        return Response.not_found()
    Response.json(user)
// scoped mutation: the value is mutable only inside the block
let config = with Config.default() as mut c:
    c.timeout = 30
    c.retries = 3

Distinctive moves.

• Explicitness where meaning is not forced. The project’s written design rule is that a character the program already determines should not have to be written, and a choice between two meanings must be. In practice this means less ceremony than Rust for inference and scoping, and deliberate spellings at the points where an author, human or agent, is most likely to be silently wrong.
• C as a first-class neighbour. c_import reads C headers directly, and with migrate translates C source into With.
• Leaks are defects. The language treats an accidental leak as a design error rather than as safe behaviour.
• Decisions are recorded. Language changes go through numbered, dated rulings with alternatives weighed, kept in the repository alongside a versioned specification.

Maturity.

A working, self-hosting compiler with CI on Linux (x86_64, aarch64), macOS (arm64) and Windows (x86_64, aarch64), nightly releases and an LSP. The specification is versioned and ahead of the implementation in places; the repository marks compiler behaviour that does not yet match a ruling as non-compliant rather than as precedent.

Agent tooling.

with init generates an AGENTS.md and CLAUDE.md in every new project, containing a compact primer on With’s syntax, ownership model, idioms and common mistakes, written for an AI assistant working in that project. The compiler itself is developed largely by agents under a human maintainer who rules on language design, and its own repository carries the same kind of guidance.