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https://github.com/Suor/funcy

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

functional-programming python utilities

Last synced: 9 days ago
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A fancy and practical functional tools

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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