Python

My small Python (~100 lines of codes) codes aren't maintainable, but I'm happy with them. I don't ever plan to work on serious projects with Python, so I can't say much about it's maintainability. But, from limited experience, I'd rather use C++, C#, or in my special case, G'MIC if maintainability matters to me.

There's one key qualifier in this sentence: I know. One's skill set matters, I guess...

Also fastest to write? I'd say JS or Ruby are just as fast or barely slower.

What most people mean is that Python has great Libraries which do the thing you want without much fuss. But thats more on the libraries than on the language.

It's not too bad if you strictly enforce Pyright, Pylint and Black.

But I have yet to work with Python code other than my own that does that. So in practice you are right.

My work uses python and it hasn't been bad for new code that has tests and types. Old code we inherited from contractors and "yolo startup" types is less good, but we've generally be improving that as we touch it.

Python has typing hints which mypy uses. It's similar to something javascripts wants to introduce call type annotations. It also has linters and formatters (ruff which does the work of multiple tools in one and is very fast). It also has unit tests built in as well as popular test libraries like pytest and nox and tox for running tests.

It is up to the maintainers to use the tools they have been given to make projects maintainable. I have worked on and seen very maintainable python projects of various sizes. While legacy code is always a bit of a nightmare (python 2 and < python 3.6), it doesn't have to be that way and getting into a python project nowadays is way easier than most other languages I've tried (maybe also because it's what I know well).

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i had the misfortune once of having to try to understand a >400kLoC python codebase in a critical position and let me tell you that maintainability is a Problem. the system was older than most of the best practices of today and had a structure i can only describe as "a duolith of sqlalchemy soup".

Yup. Part of what makes python so easy and fast is the lack of things built into languages so they are maintainable in a large project.

Take duck typing. It's so easy when you have a small project that can fully understood by a developer. Get into a big project with 10000 classes and you need explicit classes and interfaces just to understand what is going on.

Python is by far one of the worst languages I've ever seen in relation to maintainability, second only to Javascript (due to missing types, which are fixed by Typescript).

Seriously, it's rare for a Python project with more than 1,000 lines to not turn into an absolute mess thanks to the layers upon layers of meta programming, weird edge cases and so on. There are whole bad patterns I've never seen beyond Python codebases.

Things are improving slowly thanks to type hints and so on, but they are still far from where they need to be. Python is used in even more dynamic ways than JS, so the type system needs to be more expressive than TS. You can't even define a function that appends two tuples with proper type hints!