https://github.com/Suor/funcy

A fancy and practical functional tools
https://github.com/Suor/funcy

functional-programming python utilities

Last synced: 8 months ago
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A fancy and practical functional tools

• Host: GitHub
• URL: https://github.com/Suor/funcy
• Owner: Suor
• License: bsd-3-clause
• Created: 2012-10-13T00:44:57.000Z (about 13 years ago)
• Default Branch: master
• Last Pushed: 2024-05-01T10:07:23.000Z (over 1 year ago)
• Last Synced: 2024-05-21T01:03:59.338Z (over 1 year ago)
• Topics: functional-programming, python, utilities
• Language: Python
• Homepage:
• Size: 1.04 MB
• Stars: 3,283
• Watchers: 71
• Forks: 141
• Open Issues: 13
• Metadata Files:
  • Readme: README.rst
  • Changelog: CHANGELOG
  • License: LICENSE

Awesome Lists containing this project

• my-awesome-starred - funcy - A fancy and practical functional tools (Python)
• awesome-list - Funcy - A collection of fancy functional tools focused on practicality. (Containers & Language Extentions & Linting / For Python)
• best-of-python - GitHub - 14% open · ⏱️ 19.09.2025): (General Utilities)
• starred-awesome - funcy - A fancy and practical functional tools (Python)
• awesome-technostructure - Suor/funcy
• awesome-python-resources - GitHub - 7% open · ⏱️ 25.08.2022): (函数式编程)
• awesome-technostructure - Suor/funcy

README

          
Funcy |Build Status|

=====

A collection of fancy functional tools focused on practicality.

Inspired by clojure, underscore and my own abstractions. Keep reading to get an overview

or `read the docs `_.

Or jump directly to `cheatsheet `_.

Works with Python 3.4+ and pypy3.

Installation

-------------

::

    pip install funcy

Overview

--------------

Import stuff from funcy to make things happen:

.. code:: python

    from funcy import whatever, you, need

Merge collections of same type

(works for dicts, sets, lists, tuples, iterators and even strings):

.. code:: python

    merge(coll1, coll2, coll3, ...)

    join(colls)

    merge_with(sum, dict1, dict2, ...)

Walk through collection, creating its transform (like map but preserves type):

.. code:: python

    walk(str.upper, {'a', 'b'})            # {'A', 'B'}

    walk(reversed, {'a': 1, 'b': 2})       # {1: 'a', 2: 'b'}

    walk_keys(double, {'a': 1, 'b': 2})    # {'aa': 1, 'bb': 2}

    walk_values(inc, {'a': 1, 'b': 2})     # {'a': 2, 'b': 3}

Select a part of collection:

.. code:: python

    select(even, {1,2,3,10,20})                  # {2,10,20}

    select(r'^a', ('a','b','ab','ba'))           # ('a','ab')

    select_keys(callable, {str: '', None: None}) # {str: ''}

    compact({2, None, 1, 0})                     # {1,2}

Manipulate sequences:

.. code:: python

    take(4, iterate(double, 1)) # [1, 2, 4, 8]

    first(drop(3, count(10)))   # 13

    lremove(even, [1, 2, 3])    # [1, 3]

    lconcat([1, 2], [5, 6])     # [1, 2, 5, 6]

    lcat(map(range, range(4)))  # [0, 0, 1, 0, 1, 2]

    lmapcat(range, range(4))    # same

    flatten(nested_structure)   # flat iter

    distinct('abacbdd')         # iter('abcd')

    lsplit(odd, range(5))       # ([1, 3], [0, 2, 4])

    lsplit_at(2, range(5))      # ([0, 1], [2, 3, 4])

    group_by(mod3, range(5))    # {0: [0, 3], 1: [1, 4], 2: [2]}

    lpartition(2, range(5))     # [[0, 1], [2, 3]]

    chunks(2, range(5))         # iter: [0, 1], [2, 3], [4]

    pairwise(range(5))          # iter: [0, 1], [1, 2], ...

And functions:

.. code:: python

    partial(add, 1)             # inc

    curry(add)(1)(2)            # 3

    compose(inc, double)(10)    # 21

    complement(even)            # odd

    all_fn(isa(int), even)      # is_even_int

    one_third = rpartial(operator.div, 3.0)

    has_suffix = rcurry(str.endswith, 2)

Create decorators easily:

.. code:: python

    @decorator

    def log(call):

        print(call._func.__name__, call._args)

        return call()

Abstract control flow:

.. code:: python

    walk_values(silent(int), {'a': '1', 'b': 'no'})

    # => {'a': 1, 'b': None}

    @once

    def initialize():

        "..."

    with suppress(OSError):

        os.remove('some.file')

    @ignore(ErrorRateExceeded)

    @limit_error_rate(fails=5, timeout=60)

    @retry(tries=2, errors=(HttpError, ServiceDown))

    def some_unreliable_action(...):

        "..."

    class MyUser(AbstractBaseUser):

        @cached_property

        def public_phones(self):

            return self.phones.filter(public=True)

Ease debugging:

.. code:: python

    squares = {tap(x, 'x'): tap(x * x, 'x^2') for x in [3, 4]}

    # x: 3

    # x^2: 9

    # ...

    @print_exits

    def some_func(...):

        "..."

    @log_calls(log.info, errors=False)

    @log_errors(log.exception)

    def some_suspicious_function(...):

        "..."

    with print_durations('Creating models'):

        Model.objects.create(...)

        # ...

    # 10.2 ms in Creating models

And `much more `_.

Dive in

-------

Funcy is an embodiment of ideas I explain in several essays:

- `Why Every Language Needs Its Underscore `_

- `Functional Python Made Easy `_

- `Abstracting Control Flow `_

- `Painless Decorators `_

Related Projects

----------------

- https://pypi.org/project/funcy-chain/

- https://pypi.org/project/funcy-pipe/

Running tests

--------------

To run the tests using your default python:

::

    pip install -r test_requirements.txt

    py.test

To fully run ``tox`` you need all the supported pythons to be installed. These are

3.4+ and PyPy3. You can run it for particular environment even in absense

of all of the above::

    tox -e py310

    tox -e pypy3

    tox -e lint

.. |Build Status| image:: https://github.com/Suor/funcy/actions/workflows/test.yml/badge.svg

   :target: https://github.com/Suor/funcy/actions/workflows/test.yml?query=branch%3Amaster