Znaczące zmiany wprowadzone w każdej wersji Pythona 3

Każda z wersji Pythona wprowadzała wiele zmian i ulepszeń - poniżej subiektywnie selektywna lista najważniejszych zmian wprowadzonych do każdej większej wersji Pythona 3:

Python 3.0 (2008-12-03):

* print statement replaced with a print() function
* dict.iterkeys(), dict.iteritems(), and dict.itervalues() removed
* Python 2’s xrange() is Python 3’s range(); Python 2’s range() is no more
* Python 2’s str is Python 3’s bytes; Python 2’s unicode is Python 3’s str
* The default Python source encoding is now UTF-8
* urllib2 module split into urllib.request and urllib.error modules
* urlparse module renamed to urllib.parse
* urllib module split into urllib.parse, urllib.request, and urllib.error modules

Python 3.1 (2009-06-26):

* The fields in strings formatted with str.format() can now omit numbering in order to be automatically numbered, as in 'Sir {} of {}'.format('Gallahad', 'Camelot')
* round(x, n) now returns an integer if x is an integer
* collections module: Counter and OrderedDict added

Python 3.2 (2011-02-20)

* New modules: argparse, concurrent.futures, html, and sysconfig
* .pyc files are now stored in _pycache_/ directories
* datetime module: timezone added

Python 3.3 (2012-09-29)

* New modules: faulthandler, ipaddress, lzma, unittest.mock, and venv
* Support for implicit namespace packages (directories without an _init_.py) added
* datetime module: New datetime methods: timestamp(), strftime(), and astimezone()

Python 3.4 (2014-03-17)

* New modules: asyncio, ensurepip, enum, pathlib, selectors, statistics, and tracemalloc
* http.server command-line interface: --bind option added

Python 3.5 (2015-09-13)

* Coroutine functions (async def), awaitable objects (await and _await()), asynchronous iteration (async for, aiter(), and anext()), and asynchronous context managers (async with, aenter(), and aexit_()) added
Multiple and/or unpackings can now be used in a single function call
* New modules: typing and zipapp
* Various additions & improvements to the asyncio module

Python 3.6 (2016-12-23)

* Formatted string literals (“f-strings”)
* Variables can now be annotated by following the name of the variable with a colon and the annotation
* Underscores can now be used in numeric literals
* await and yield can now be used in the same function, thereby enabling asynchronous generators
* async for can now be used in list, set, & dict comprehensions and in generator expressions
* await expressions can now be used in any comprehension
*kwargs now preserves insertion order
* dicts are now implemented in such a way that they preserve insertion order
* Various additions & improvements to the asyncio module

Python 3.7 (2018-06-27)

* dicts are now guaranteed to preserve insertion order
* async and await are now reserved keywords
* New modules: contextvars, dataclasses, importlib.resources

Python 3.8 (2019-10-14)

* Assignment expressions: := (the “walrus operator”) can now be used to assign a value to a variable in the middle of an expression
* Function parameters can now be made positional-only by placing a / after them in the argument list

Python 3.9 (2020-10-05)

* dicts can now be merged & updated using the | and |= operators
* New modules: graphlib and zoneinfo
* asyncio module: to_thread() added
* Removed: asyncio.Task.current_task() and asyncio.Task.all_tasks() (deprecated since Python 3.7); use asyncio.current_task() and asyncio.all_tasks() instead

Python 3.10 (2021-10-04)

* Pattern matching with match/case syntax
* Common syntax errors now have better error messages

Python 3.11 (2022-10-03)

* Exception groups
* Traceback messages now highlight the exact expression that caused the error
* New modules: tomllib and wsgiref.types