frozenlist

A list-like structure which implements collections.abc.MutableSequence

frozenlist Permissive license Apache-2.0 Active ★ 124 v1.8.0 released 2025-10-06

Install

frozenlist on PyPI

pip

pip install frozenlist

uv

uv add frozenlist

poetry

poetry add frozenlist

Package facts

License	Apache-2.0 (permissive)
Python support	supports the current Python release (>=3.9)
Install friction	low — pure-Python wheel
Runtime dependencies	none
Maintenance	actively maintained — 311 days since the last release
Last repo commit	2026-08-10
First released	2019-08-28
Popularity	one of the 100 most-downloaded packages on PyPI (30-day window, as of 2026-08-13)
Known vulnerabilities	none known (OSV.dev, checked 2026-08-13)

Evidence: frozenlist-1.8.0-py3-none-any.whl

Development Status :: 5 - Production/StableIntended Audience :: DevelopersOperating System :: MacOS :: MacOS XOperating System :: Microsoft :: WindowsOperating System :: POSIXProgramming Language :: CythonProgramming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPy

About frozenlist

from the package's own PyPI description — quoted content, verbatim

frozenlist

.. image:: https://github.com/aio-libs/frozenlist/workflows/CI/badge.svg :target: https://github.com/aio-libs/frozenlist/actions :alt: GitHub status for master branch

.. image:: https://codecov.io/gh/aio-libs/frozenlist/branch/master/graph/badge.svg?flag=pytest :target: https://codecov.io/gh/aio-libs/frozenlist?flags[]=pytest :alt: codecov.io status for master branch

.. image:: https://img.shields.io/pypi/v/frozenlist.svg?logo=Python&logoColor=white :target: https://pypi.org/project/frozenlist :alt: frozenlist @ PyPI

.. image:: https://readthedocs.org/projects/frozenlist/badge/?version=latest :target: https://frozenlist.aio-libs.org :alt: Read The Docs build status badge

.. image:: https://img.shields.io/matrix/aio-libs:matrix.org?label=Discuss%20on%20Matrix%20at%20%23aio-libs%3Amatrix.org&logo=matrix&server_fqdn=matrix.org&style=flat :target: https://matrix.to/#/%23aio-libs:matrix.org :alt: Matrix Room — #aio-libs:matrix.org

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AI interpretation — verify before relying

AI-generated interpretation of the package facts above; every digit, version, license, or vulnerability id it cites is grounded in the facts already shown on this page

frozenlist provides a mutable list that can be frozen to prevent further modifications, raising RuntimeError on mutation attempts after freeze() is called, and supporting hashing only when frozen.

Low friction: pure wheel distribution (frozenlist-1.8.0-py3-none-any.whl) with no runtime dependencies. Active maintenance with last commit 2026-08-10 and recent v1.8.0 release (2025-10-06).

Apache-2.0 is permissive; you may use, modify, and distribute frozenlist freely in commercial or proprietary projects provided you include a copy of the license and note material changes.

Usage

pip install frozenlist

from frozenlist import FrozenList
fl = FrozenList([17, 42])
fl.append('spam')
fl.freeze()
# fl.append('Vikings') would raise RuntimeError

Verdict: frozenlist is a stable, actively maintained utility (top-100 PyPI tier, no known vulnerabilities) offering a simple pattern for transitioning lists from mutable to immutable with zero external dependencies and broad Python 3.9+ support including PyPy.

Needs verification

Performance characteristics of frozen vs. unfrozen list operations compared to alternatives
Whether the Cython-accelerated build is reliably available across all target platforms

immutable list pythonfrozen list data structurehashable list collectionprevent list modificationmutable to immutable listlist freeze lockcollections abc mutablesequence