lemma 0.9.2

A pure, declarative language for business rules.
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nav_title: Tools & SDKs
nav_order: 50
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# Tools & SDKs

Ways to run Lemma, from embedding the engine in your app to driving it from the command line.

## Lemma SDKs

Embed Lemma directly in your language:

- [Rust]rust.md
- [Elixir]elixir.md
- [JavaScript / TypeScript]javascript.md
- [Maven]maven.md
- [Python]python.md (coming soon)
- [C# / .NET]dotnet.md (coming soon)

More SDKs are on the way. Precompiled binaries make each new one straightforward to add.

## Command line & servers

- [Lemma CLI]../reference/cli.md: `lemma run`, `show`, `list`, `format`, `fetch`, plus `server`, `lsp`, and `mcp`
- [Lemma MCP]../reference/cli.md#lemma-mcp-start-mcp-server: expose specs to AI assistants over the Model Context Protocol
- [Registry: LemmaBase]../reference/registry.md: share and reuse specs via `@owner/name` imports on `uses`

## Notes that apply to every SDK

- Same engine underneath, so results are identical across languages.
- `load` validates: invalid specs are rejected there, never at run time.
- The engine never hits the network. Resolve `@...` [registry]../reference/registry.md references before loading.
- Explanations are opt-in (`explain: true` / `--explain`). Wire shape: [`api.v1.json`]../schemas/api.v1.json (`RuleResult.explanation``RuleNode`; nested tree under `ExplanationNode`).
- Maven package requires **JDK 21+**.
- Editor support (any language): the [VS Code / Cursor extension]../installation.md drives `lemma lsp`.