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Comment by goodoldneon | Hacker News Reader

This is a terrible take. Using type annotations doesn’t mean Python is no longer a dynamically typed language

This guy is full of terrible takes. Like his claim that typing catches "one bug a year".

If you enforce them then you can't do duck typing, this means adding lots of boilerplate code to your code base, increasing the amount of bugs, since bugs are proportional to the total number of lines of code in the project.

Typing related bugs that aren't caught in unit testing are very rare.

Any additional bugs per lines of code, which would be less in a strictly typed language anyway, is worth the structure you get from a typed language.

I disliked JavaScript and love python. Typescript has replaced python as my labor of love language for now but a typed python in a similar manner would be great

Typing doesn't remove many bugs from Python code (probably about 1 bug per year). It's statisically insignificant.

JavaScript is a bad language and adding stuff to it makes it better. The same isn't true for Python.

> If you enforce them then you can't do duck typing,

This is a little misleading as mypy and pyright both support structural typing.

> If you enforce them then you can't do duck typing, this means adding lots of boilerplate code to your code base, increasing the amount of bugs, since bugs are proportional to the total number of lines of code in the project.

You can still do duck typing. Python's Protocol and TypedDict do that for objects and dicts, respectively. Python also has sum types. I've added type annotations to thousands of lines of legacy code and rarely have I had to change any logic to accommodate.

> Typing related bugs that aren't caught in unit testing are very rare.

Not true at all. Unless you're writing unit tests that cover every possible code path, your unit tests will miss stuff. And I'd argue that 100% test coverage is a Herculean effort to write and maintain, and isn't worth it. Static analysis gives you tons of checking for free. The biggest benefit is forcing you to properly handle function arguments that could be None. Are you always checking that values aren't None before using them?

Static analysis using static typing gives you almost nothing at all in practice.

It searches for a very narrow and rare set of bugs, which hardly ever happen.

Typing really exists to help a compiler, it's not a code correctness tool in the way you envision.

It absolutely is a code correctness tool. If I have a function that should only accept a string then static analysis will error in all the places that pass anything else. As long as you validate your inputs (i.e. request validation) then the type annotations are representative of the runtime types

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