# Lemma CLI
> **A command-line interface for the Lemma language.**
This package provides the `lemma` CLI for running, inspecting, and serving Lemma docs. It ships alongside the `lemma-engine` crate and exposes the same deterministic, auditable evaluation pipeline from the terminal.
## Status
Lemma is still early-stage and **not yet recommended for production use**. Expect breaking changes and evolving commands while the toolchain stabilizes.
## Installation
```bash
cargo install lemma-cli
```
After installation the `lemma` binary is available on your PATH.
## Common commands
```bash
# Evaluate a document (all rules)
lemma run shipping
# Evaluate specific rules
lemma run tax_calculation:tax_owed
# Override facts at runtime
lemma run tax_calculation income=75000 filing_status="married"
# Explore documents interactively
lemma run --interactive
# Show document structure
lemma show pricing
# List available documents
lemma list ./documentation/examples
# Start the HTTP server
lemma server --port 3000 --dir ./documentation/examples
# Start the MCP server (AI assistant integration)
lemma mcp --dir ./documentation/examples
```
Each command supports `--help` for full usage details.
## Features
- **Deterministic evaluations** – same audit trail as the engine library
- **Interactive mode** – select documents, rules, and facts without typing full paths
- **HTTP server** – evaluate documents over REST, perfect for integration tests and dashboards
- **MCP server** – expose Lemma to AI assistants via the Model Context Protocol
- **Machine-readable output** – `--raw` flag for tooling and pipelines
## Example session
```bash
lemma run shipping
# Output:
# ┌───────────────┬──────────────────────────────────────────────────────┐
# │ Rule ┆ Evaluation │
# ╞═══════════════╪══════════════════════════════════════════════════════╡
# │ express_fee ┆ 4.99 │
# │ ┆ ... │
# └───────────────┴──────────────────────────────────────────────────────┘
```
Enable raw mode to pipe results:
```bash
lemma run shipping --raw > output.json
```
## Documentation
- CLI reference: <https://github.com/benrogmans/lemma/blob/main/documentation/CLI.md>
- Language guide: <https://benrogmans.github.io/lemma/>
- API docs (engine): <https://docs.rs/lemma-engine>
- Examples: <https://github.com/benrogmans/lemma/tree/main/documentation/examples>
- Roadmap: <https://github.com/benrogmans/lemma/blob/main/documentation/roadmap.md>
## Contributing
Contributions are very welcome! See [documentation/contributing.md](https://github.com/benrogmans/lemma/blob/main/documentation/contributing.md) and the [project roadmap](https://github.com/benrogmans/lemma/blob/main/documentation/roadmap.md) for ideas.
## License
Apache 2.0