.. _use-sequence-for-iteration:

use-sequence-for-iteration / C0208
==================================

**Message emitted:**

``Use a sequence type when iterating over values``

**Description:**

*When iterating over values, sequence types (e.g., ``lists``, ``tuples``, ``ranges``) are more efficient than ``sets``.*

**Problematic code:**

.. literalinclude:: /data/messages/u/use-sequence-for-iteration/bad.py
   :language: python

**Correct code:**

``list.py``:

.. literalinclude:: /data/messages/u/use-sequence-for-iteration/good/list.py
    :language: python


``tuple.py``:

.. literalinclude:: /data/messages/u/use-sequence-for-iteration/good/tuple.py
    :language: python



**Additional details:**

https://gist.github.com/hofrob/8b1c1e205a0d4c66a680b1fe4bfeba11

This example script shows a significant increase in performance when using a list, tuple or range over a set in python version 3.11.1.



Created by the `refactoring <https://github.com/pylint-dev/pylint/blob/main/pylint/checkers/refactoring/recommendation_checker.py>`__ checker.