How to Install `frozenlist` in Python

v1.8.0 General Purpose Python >=3.9 Apache-2.0

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

Install pip install frozenlist

What is frozenlist?

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

`` is a list-like structure which implements `` is called, after which list modifications raise ``:

>>> from frozenlist import FrozenList >>> fl = FrozenList([17, 42]) >>> fl.append('spam') >>> fl.append('Vikings') >>> fl >>> fl.freeze() >>> fl >>> fl.frozen True >>> fl.append("Monty") Traceback (most recent call last): File " ", line 1, in File "frozenlist/frozenlist.pyx", line 97, in frozenlist.frozenlist.FrozenList.append self.checkfrozen() File "frozenlist/frozenlist.pyx", line 19, in frozenlist.frozenlist.FrozenList.checkfrozen raise RuntimeError("Cannot modify frozen list.") RuntimeError: Cannot modify frozen list.

FrozenList is also hashable, but only when frozen. Otherwise it also throws a RuntimeError:

Documentation → PyPI page →

Quick Start

Minimal example to get started with frozenlist:

import frozenlist

print(frozenlist.__version__)

Installation

pip (standard)

pip install frozenlist

Virtual environment (recommended)

python -m venv venv
source venv/bin/activate   # Windows: venv\Scripts\activate
pip install frozenlist

pip3

pip3 install frozenlist

conda

conda install -c conda-forge frozenlist

Poetry

poetry add frozenlist

Verify the Installation

After installing, confirm the package is available:

python -c "import frozenlist; print(frozenlist.__version__)"

If this prints a version number, installation succeeded. If you see a ModuleNotFoundError, see the errors section below.

Installation Errors

Common errors when installing frozenlist with pip.

ModuleNotFoundError: No module named 'frozenlist'

Cause: The package is not installed in the current Python environment.

Fix: Run pip install frozenlist. If using a virtual environment, ensure it is activated first.

ModuleNotFoundError: No module named 'frozenlist' (installed but still failing)

Cause: pip installed the package into a different Python than the one running your script.

Fix: Use python -m pip install frozenlist to install into the interpreter you are running.

ImportError: cannot import name 'X' from 'frozenlist'

Cause: The function or class does not exist in the installed version.

Fix: Check the version with pip show frozenlist and upgrade with pip install --upgrade frozenlist.

pip: command not found

Cause: pip is not in PATH or Python was not added to PATH during installation.

Fix: Try python -m pip install frozenlist. On macOS/Linux try pip3.

PermissionError: [Errno 13] Permission denied

Cause: No write access to the system Python package directory.

Fix: Use a virtual environment, or add --user: pip install --user frozenlist

SSL: CERTIFICATE_VERIFY_FAILED

Cause: pip cannot verify PyPI's SSL certificate — common behind corporate proxies.

Fix: Try: pip install --trusted-host pypi.org --trusted-host files.pythonhosted.org frozenlist

Recent Releases

Version	Released
`1.8.0` latest	2025-10-06
`1.7.0`	2025-06-09
`1.6.2`	2025-06-03
`1.6.1`	2025-06-02
`1.6.0`	2025-04-17

Full release history on PyPI →

Manage frozenlist

Upgrade to latest version

pip install --upgrade frozenlist

Install a specific version

pip install frozenlist==1.8.0

Uninstall

pip uninstall frozenlist

Check what is installed

pip show frozenlist

Last updated: 2026-04-11 • Data from PyPI

How to Install frozenlist in Python