How to install the facet-python crate // Lib.rs

Adding `facet_python` library as a dependency

Run this command in a terminal, in your project's directory:

cargo add facet-python

To add it manually, edit your project's Cargo.toml file and add to the [dependencies] section:

facet-python = "0.43.2"

The facet_python library will be automatically available globally. Read the facet_python library documentation.

Back to the crate overview.

Readme

Generate Python type definitions from facet type metadata.

Overview

This crate uses facet's reflection capabilities to generate Python type hints and TypedDicts from any Rust type that implements Facet. This enables type-safe interop when your Rust code exchanges data with Python.

Example

use facet::Facet;
use facet_python::to_python;

#[derive(Facet)]
struct User {
    name: String,
    age: u32,
    email: Option<String>,
}

let python_code = to_python::<User>(false);

This generates:

from typing import TypedDict, Required, NotRequired

class User(TypedDict, total=False):
    name: Required[str]
    age: Required[int]
    email: str  # Optional fields become NotRequired

Type Mappings

Rust Type	Python Type
`String`, `&str`	`str`
`i32`, `u32`, etc.	`int`
`f32`, `f64`	`float`
`bool`	`bool`
`Vec<T>`	`list[T]`
`Option<T>`	`T` (NotRequired in TypedDict)
`HashMap<K, V>`	`dict[K, V]`
Struct	`TypedDict`
Enum	`Union[...]` of variants

Features

Recursive types: Handles nested structs and enums
Documentation: Preserves doc comments as Python docstrings
Reserved keywords: Automatically handles Python reserved words as field names
Generic support: Maps Rust generics to Python type parameters

Adding facet_python library as a dependency

Adding `facet_python` library as a dependency