---
id: fable-library
version: "5.13.0"
license: MIT
license_treatment: permissive
maintenance: active
---

# fable-library — Fable library for Python

License: permissive · Maintenance: active · Downloads: 139.6K/mo

## What it is and what it does

Fable Library for Python is the runtime foundation for F# code compiled to Python via the Fable compiler. It bridges the gap between F# semantics and Python execution by providing type definitions, runtime utilities, and Rust-based extensions for features like unsigned integers that Python doesn't natively support. The library uses a two-tier architecture combining Python components for core functionality with Rust extensions for performance and proper type representation.

The package is distributed as pre-built wheels across multiple platforms and architectures, making it straightforward to install as a dependency. Library authors can choose between bundling it with their compiled code or declaring it as a PyPI dependency; the PyPI approach is required for libraries intended for distribution beyond a single machine.

Use it for:

- Running F# libraries compiled to Python that depend on unsigned integer types
- Distributing cross-platform F# code as Python packages with proper type support
- Integrating F# and Python codebases where F# components are compiled to Python
- Accessing performance-critical Rust implementations for operations not efficiently done in pure Python

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Fable Library for Python provides runtime support and type definitions for F# code compiled to Python, including Rust-based extensions for unsigned integer types and performance-critical operations.

Yes, if you are using F# code compiled to Python via Fable. It is a required runtime dependency for such projects and is actively maintained with no known vulnerabilities. The MIT license and broad platform support make it a straightforward addition. If you are not using Fable-compiled F# code, there is no reason to install it.

## Install

pip install fable-library
uv add fable-library
poetry add fable-library

## Installing fable-library

Before you install: Medium install friction due to compiled Rust extensions across multiple platforms, but wheels are pre-built for all major architectures. Actively maintained with a release 21 days ago.

License in practice: MIT license permits unrestricted use, modification, and distribution in both open-source and commercial projects.

Quickstart:

pip install fable-library==5.13.0

import fable_library
# Use Fable-compiled F# code in Python

Requires Python 3.10 or later; Python 4.0 and above are not supported.

Verify before relying:

- What specific Rust extensions are included and what performance gains they provide
- How to integrate Fable-compiled F# modules with this library
- Whether the bundled vs. PyPI distribution choice affects runtime behavior

## Package facts

- License: MIT (permissive)
- Python support: supports_current
- Install friction: medium
- Maintenance: active
- Downloads: 139.6K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

F# to Python runtime, Fable Python library, F# compiled Python support, unsigned integers Python, F# interop Python, fsharp-interop, compiled-language-runtime

[View on SkillFed](https://skillfed.io/packages/fable-library) · [View on PyPI](https://pypi.org/project/fable-library/)