Is there any way linter/type checker for #Python that can find expressions that never will evaluate to anything other than False based on the type information? E.g. checking if a variable of the type `int` exists within a list of the type `list[str]`? I do use #mypy but it doesn't seem to catch this.

Git-хуки, которые не дают коммитить плохой код

Здравствуйте, коллеги программисты! Большинство фейлов в CI — это мелочи: забытый console.log , форматирование, линт, сломанный импорт, файл без теста. Такие ошибки не должны доезжать до сборки или код-ревью. Git-хуки позволяют запускать проверки прямо во время git commit и блокировать коммит, если были обнаружены нарушения. В прошлой статье я рассказывал про скрипты, которые я использую для проверки качества кода в PHP/Laravel. В этой статье я хочу рассказать о скриптах для JavaScript/TypeScript и Python — линтинг, форматирование, тесты, статический анализ и проверка наличия тестов. Все скрипты описанные в статье находятся здесь - https://github.com/prog-time/git-hooks

https://habr.com/ru/articles/993870/

#линтер #git_hooks #javascript #python #eslint #prettier #tsc #vitest #mypy #pytest

The only criticism I have of types in Python:

Python is a really good dynamically typed language. Since classes are themselves instances of a class-describing object, you can do what other languages have to do with text-transforming macros by just treating the class as mutable and dynamically adding things like methods.

... and then the type system kicks your ass for doing that, so you're left with a few not-great options.

#python #mypy

[Mypy에서 Ty로: Ruff 제작사가 만든 초고속 Rust 기반 Python 타입 체커 도입 가이드

Astral사는 새로운 Rust 기반 Python 타입 체커인 'ty'를 출시했습니다. 이 도구는 Mypy의 엄격 모드와 유사한 기능을 제공하며, 빠른 실행 속도를 자랑합니다. 설치 및 사용 방법, GitHub Actions와의 통합 방법, 그리고 커뮤니티 기반의 pre-commit 워크어라운드에 대한 가이드가 제공되었습니다.

https://news.hada.io/topic?id=25713

#python #typechecking #rust #ty #mypy

Январский рефакторинг: 7 дней, чтобы почистить Python веб‑проект

Январь - самое удобное время разобрать завалы в проекте. Пол‑команды ещё в отпусках, pull‑реквестов меньше, product owner'ы только вспоминают, что планировали делать в этом году - можно спокойно пройтись по коду и навести порядок. В этой статье пойдёт речь о нескольких косметических действиях, которые, с одной стороны, почти не затрагивают логику программы и не вызывают ненависти у тестировщиков, а с другой - делают код чуть приятнее и дают темы для обсуждения на бэкенд‑созвонах. Мы разложим импорты, перенесём логику из роутов в контроллеры, а из контроллеров - в репозитории и сервисы, избавимся от requirements.txt в пользу нормального менеджера зависимостей и включим mypy.

https://habr.com/ru/articles/983172/

#python #backend #refactoring #architecture #linter #mypy #litestar

I think that my Python code editor is ready for 2026!

Using Flycheck and happy about how simple it was to add a custom syntax checker. 👏

I've configured my Emacs to auto-switch between flake8 or ruff, and mypy or the brand new type checker "ty" depending on what's in the local environment.

Pull request to my emacs configuration with details about the implementation:
https://github.com/DavidVujic/my-emacs-config/pull/23/changes

#python #emacs #mypy #flake8 #ruff #ty #elisp #flycheck

With high-performance #Python type checkers like #Pyright, #Pyrefly, and #ty now available, what's the value proposition of #Mypy? Is it the reference implementation? Or does Mypy still have the most features? I'm not trying to knock Mypy, I'm genuinely asking because I don't know.

ty: революция в тайп-чекинге

Всем привет! За последние пару лет компания Astral буквально разрывает Python-мир своими инструментами. Даже если вы не слышали это имя напрямую, с большой вероятностью вы уже пользовались их продуктами — ruff или uv . И это не преувеличение. И ruff , и uv сегодня фактически стали стандартом индустрии. Например, в свежем релизе PyCharm 2025.3 при создании нового проекта по умолчанию инициализируется именно окружение uv , а не привычный venv . Для open source-проекта — это очень серьёзный показатель доверия со стороны экосистемы. Открытый исходный код и массовое принятие инструментов Python-разработчиками дали Astral тот самый «кредит доверия», который компания, судя по всему, пока что уверенно оправдывает. И вот буквально на днях Astral объявили, что их новый «революционный» тайп-чекер ty переходит в стадию бета-тестирования. А если учитывать, что и uv , и ruff формально тоже всё ещё находятся в бете, то можно считать, что ty уже фактически вышел в релиз. Собственно, о нём и поговорим дальше. Если вам интересны подобные материалы — подписывайтесь на Telegram-канал «Код на салфетке» . Там я делюсь гайдами для новичков и полезными инструментами. А прямо сейчас у нас ещё и проходит новогодний розыгрыш.

https://habr.com/ru/articles/979752/

#uv #ruff #ty #mypy #type_checking #python #rust #astral

I’ve published a PR that adds an `unsafe-subtype` error to mypy, primarily to address unsafe `date`/`datetime` use cases. I would appreciate any reviews or feedback. Thanks! https://github.com/python/mypy/pull/20448 #python #typing #mypy

I have been investigating this:
```Python
from numbers import Real
def positive(x: Real) -> bool:
return x > 0 # Type Check failed!
```

#PEP 484 said that one should use `float` instead, but this does not solve for other numerical types e.g. #GMP numbers or #NumPy numbers.

And I found some old threads like https://github.com/python/typing/issues/1663
https://github.com/python/mypy/issues/3186
https://discuss.python.org/t/numeric-generics-where-do-we-go-from-pep-3141-and-present-day-mypy/17155
https://discuss.python.org/t/clarifying-the-float-int-complex-special-case/54018/26

And it seems like none has make any real progress.

To my understanding, ABC should also provides a good protocol for typing, just like typeclasses in #Haskell.

#Python #Typing #MyPy #Pyright

🚀🎉 Hold onto your keyboards, folks! #Astral has unleashed "ty," a lightning-fast #Python #type #checker, because, of course, we needed another one. Written in #Rust, because Python apparently wasn't fast enough for checking itself, "ty" is now in #Beta and ready to bravely enter a market already saturated with the likes of #mypy, #Pyright, and other tools you didn't know you couldn't live without. 🌪️🔧
https://astral.sh/blog/ty #ty #HackerNews #ngated

I have a script called pyfix which runs mypy and ruff to

- have strong typing
- have a fixed and orderly import order
- have the file always formatted in the same way
- detect programming errors and redundancies.

Now I am working on gitlogui (https://codeberg.org/harald/gitlogui) the main script of which I called glu. So I am running

pyfix glu

all the time, which reads funny. 😀

#python #gitlogui #mypy #ruff #strongTyping #linting

Pythonの型チェックでmypy使ってみた
https://qiita.com/yomu_n/items/95fe59545c59096cd789?utm_campaign=popular_items&utm_medium=feed&utm_source=popular_items

#qiita #Python #mypy #型ヒント

have you ever annotated a TypedDict onto the **kwargs fuction and want Sphinx to automatically add it to the function's docstring?

class GreetingKwargs(TypedDict):
name: Annotated[str, Doc("the name of the person to greet")]

def greet(**kwargs: Unpack[GreetingKwargs]):
"""Greet a person.

:returns: A nice greeting
"""
return f"hello, {kwargs['name']}!"

i wrote a plugin for it https://github.com/cthoyt/sphinx-unpack

#python #sphinx #mypy #typing

Python type-checkers should infer Final from all-caps named variables. https://github.com/python/mypy/issues/19987 Consider adding a thumb up :) #python #typing #mypy

Introducting: `stormcheck mypy --edu` , type check your code, and learn #Python fundamentals at the same time!

The error messages themselves are ordered by difficulty level, and each category has a dedicated tutorial built-in to the CLI!

My goal was to create a tool that can teach beginners as they work, but still be useful to professionals who already know their craft.

We call this Compassion-Driven-Development

Once finished, I plan on putting this on all my open-source projects to help contributors who are new to Python.

Soon: RUFF checking as well?? What else would a tool like this benefit from?

#OpenSource #CLI #mypy #education #programming #teaching #learning

I have a Python static typing conundrum. I'd like a solution that works with mypy.

I have a function which fills out a list, albeit not "in order", so it's inconvenient to write it as a list comprehension or similar.

So, I fill the list with [None] and assert that all the Nones are gone by the time it returns.

However, the assertion I wrote does NOT convince mypy that the type of result now matches the return type of f, and I get a diagnostic: Incompatible return value type (got "list[int | None]", expected "list[int]")

def f() -> list[int]:
    result: list[int|None] = [None] * 3
    result[0] = 1
    result[2] = 2
    result[1] = 3
    assert not any(i is None for i in result)
    return result

Any hints? Can I do something besides cast the return value?

Solution: I used TypeGuard (python 3.10+) as suggested in replies. I can accept the runtime overhead.

#askMastodon #python #mypy #answered

At this point, I think writing #Python without #mypy --strict is insane.

And a side-effect is that if you add a new dependency, there's a solid chance you have to spend a day writing stubs for it. Helps keep bloat down and also means you get a decent tour of the library.

Okay, so, fans of the #TwistedFramework help me out here:

I am mucking around with writing a simple new thing that, in order to have type annotations that aren't *completely* useless, needs to deal with the fact that Protocol and Factory aren't annotated.

But adding annotations makes the entire framework notice that the pattern of paired-Protocol-and-Factory subclasses are inherently LSP violations, because .protocol and .factory are writable attributes and thus invariant.

#python #mypy

The pythonbuilder got a few improvements. Apart from introducing ruff as a consistent python code formatter and for linting in addition to mypy, it got a new module pbpython.py which wraps

- ruff check
- ruff format
- mypy

calls for easy use as target builders.

https://codeberg.org/harald/pythonbuilder

#pythonbuilder
#buildmachine
#bashbuilder
#buildsystem
#buildtool
#softwaredevelopment
#programming
#python
#ruff
#mypy