statem

A minimal state machine engine, built as two independent, idiomatic sibling libraries: statem-py (Python, published to PyPI as statem) and statem-rs (Rust crate statem-rs). Same design philosophy, two implementations — see each directory's own docs for language-specific usage.

Why this shape

• Config is data, not code. The state graph (on / always / entry / exit / error_state) is a plain, JSON/YAML-friendly structure — author it by hand, generate it, or load it from a file, database, or LLM.
• Guards and actions are ordinary functions, registered by name, independent of the graph. No subclassing, no framework lifecycle to inherit into.
• Fails fast. Bad transition targets and unregistered guard/action names are caught at construction time, not three hops into a live run.
• Every run is traceable. Each guard/action that fires is recorded in order, so you can see exactly why the machine ended up where it did.
• One philosophy, two languages, on purpose. statem-py and statem-rs aren't a port of one into the other — each is written the way its language naturally does this: Pydantic validation and duck-typed sessions in Python; the borrow checker, Display, and typed errors in Rust.

Packages

Package	Language	Docs
statem-py	Python (PyPI: statem)	statem-py/README.md
statem-rs	Rust (crate: statem-rs)	statem-rs/Cargo.toml

License

MIT — see LICENSE.