3 ms·

This isn't the first time I've seen this argument- clearly there are people that it rings true for, but I just have a hard time seeing it. The benefits you get

This isn't the first time I've seen this argument- clearly there are people that it rings true for, but I just have a hard time seeing it. The benefits you get from types start to very quickly diminish as soon as you start adding untyped values into the mix. Sure, there are the odd cases where you might happen to have a typed function and a typed value and the checker can find a bug for you, but my experience writing python tells me these cases in reality are vanishingly rare. And the cost of this flexibility seems to be quite high. The overall quality of type checking that mypy gives you seems to be pretty abysmal, and it requires quite a bit more handholding and awkward workarounds to deal with the proliferation of any's and uninferable types than a language that just starts with types in the first place.

ehsankia 7y ago
Not really. Enable something like MyPy or PyType on a big enough codebase with zero explicit annotation and it'll already find plenty of bugs and unhandled cases from the inferred types alone. Some of these are stuff a strong IDE may catch too (using the wrong function name, passing wrong number of args, etc), but some other ones are actually deeper in the code. So already, with zero annotations, you already get value out, let alone once you type a few tricky variables that are harder for Python to track.
- rebeccaskinner 7y ago
  I've never seen that personally, but most of my python work has been on small to medium sized projects (generally in the 5-10 KLOC range).
  - nl 7y ago
    What kind of "untyped data" are you dealing with?
Too 7y ago
That's like saying the value of unit tests quickly diminish once you add non tested code to the mix. For fearless refactoring, sure, you need quite high type-coverage to not get a false sense of security, but still, the more you have the safer it is. For just finding bugs and code navigation, any addition of types is going to be a win.

ehsankia 7y ago

Not really. Enable something like MyPy or PyType on a big enough codebase with zero explicit annotation and it'll already find plenty of bugs and unhandled cases from the inferred types alone. Some of these are stuff a strong IDE may catch too (using the wrong function name, passing wrong number of args, etc), but some other ones are actually deeper in the code. So already, with zero annotations, you already get value out, let alone once you type a few tricky variables that are harder for Python to track.

rebeccaskinner 7y ago
I've never seen that personally, but most of my python work has been on small to medium sized projects (generally in the 5-10 KLOC range).
- nl 7y ago
  What kind of "untyped data" are you dealing with?

Too 7y ago

That's like saying the value of unit tests quickly diminish once you add non tested code to the mix. For fearless refactoring, sure, you need quite high type-coverage to not get a false sense of security, but still, the more you have the safer it is. For just finding bugs and code navigation, any addition of types is going to be a win.