zerolang

zerolang is a pre-1 programming language experiment with compiler APIs designed for agent workflows.

Agent-first refers to the compiler and tooling interfaces exposed for programmatic use. An agent can load language rules for the compiler binary in use, inspect source through stable command contracts, read diagnostics with repair metadata, produce a small edit, and rerun the same checks.

Safety status

Security vulnerabilities should be expected. zerolang is not ready for production systems, sensitive data, or trusted infrastructure. Run and develop it in isolated, disposable environments.

Agent Workflow Interfaces

A small program shows function definitions, return rows, prefix calls, fallibility, and indentation:

fn answer i32
  ret + 40 2

pub fn main Void world World !
  if == answer() 42
    check world.out.write "math works\n"

The compiler exposes the workflow through CLI commands with stable structured output.

Load Version-Matched Rules

The compiler ships skill text that matches the binary being used:

zero skills list
zero skills get zero-language
zero skills get zero-diagnostics
zero skills get zero-stdlib

Print the language guide bundled with the compiler:

zero skills get zero-language

Inspect Compiler Facts

Compiler state is exposed through structured command output instead of prose-only output. The important contract is the stable fields and repair identifiers; today the CLI exposes those fields with --json:

zero tokens --json examples/hello.0
zero parse --json examples/hello.0
zero check --json examples/hello.0
zero graph --json examples/systems-package
zero size --json examples/point.0

The JSON contracts include diagnostic codes and spans, public symbols, import edges, target readiness, compile-time sandbox facts, retained helpers, and size retention reasons.

Compiler-Native Contracts

Most language ecosystems expose some of these facts through separate tools, editor protocols, or library APIs. zerolang keeps the agent-facing inspection and repair path in the compiler CLI.

The inspection and repair surfaces are compiler commands, not editor-only features or a separate analysis service:

Command	Contract
zero skills get zero-language	Version-matched language rules bundled with the compiler binary.
zero check --json	Diagnostics with code, span, expected/actual fields, fix safety, repair metadata, compile-time sandbox facts, and target readiness.
zero parse --json	A stable parse summary with declarations, function signatures, and body node kinds.
zero graph --json	Modules, imports, public symbols, capabilities, effects, ownership facts, helper use, and interface fingerprints.
zero fix --plan --json	Typed repair plans that describe proposed fixes without editing files.
zero size --json	Retained helpers, size reasons, profile policy, backend facts, and artifact budget data.

Repair With Diagnostics

A failing fixture reports a diagnostic with stable fields:

zero check --json conformance/check/fail/unknown-name.0

Today that output includes fields like:

{
  "code": "NAM003",
  "message": "unknown identifier 'message'",
  "expected": "visible local, parameter, function, or builtin",
  "actual": "no matching visible symbol",
  "repair": {
    "id": "declare-missing-symbol"
  }
}

Diagnostics can be explained and turned into typed fix plans:

zero explain --json TYP009
zero fix --plan --json examples/agent-repair-demo/broken.0

Run the repair demo:

pnpm run agent:demo

See examples/agent-repair-demo/ for the broken fixture, suggested edit, fixed fixture, and scripted check-explain-plan-rerun flow.

Compatibility Policy

zerolang is intentionally unstable before 1.0. The repo prefers one current syntax and one formatted style over compatibility layers:

zero fmt --check examples/hello.0
zero check --json examples/hello.0

Before 1.0, the project may make breaking changes to simplify the language, standard library, diagnostics, or inspection APIs for agent use.

Quick Start

Install the latest release:

curl -fsSL https://zerolang.ai/install.sh | bash
export PATH="$HOME/.zero/bin:$PATH"
zero --version

Check a program:

zero check examples/hello.0

Run a small executable:

zero run examples/add.0

Expected output:

math works

Common Commands

zero check examples/hello.0
zero run examples/add.0
zero build --emit exe --target linux-musl-x64 examples/add.0 --out .zero/out/add
zero graph --json examples/systems-package
zero size --json examples/point.0
zero skills get zero --full
zero doctor --json

Validation

pnpm run docs:test
pnpm run conformance
pnpm run native:test
pnpm run command-contracts

Benchmarks run locally by default:

pnpm run bench