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You're correct but this barely changes the authors points: "It’s virtually impossible to statically analyze" and "In Python a good amount of errors are disco

by tln 8y ago

You're correct but this barely changes the authors points: "It’s virtually impossible to statically analyze" and "In Python a good amount of errors are discovered at runtime"

lvh 8y ago
The rest of the points are silly rehashes of arguments as old as Emacs v vim, but sure, let's go there too. We've done empirical research to see if this matters. Charitably, the results are "inconclusive"[0]. > The first glaring issue is that I have no guarantee that is_valid() returns a bool type. You can name functions ridiculous, unhelpful and misleading things in any language. The very fact that you know to expect a bool undermines the point: clearly, despite not having static types, a human managed to make a pretty reasonable assumption about what a piece of code was about to do. Just because the compiler can check that is_valid returns a string doesn't mean that hat's magically a useful thing to do. > The fact that I cannot, in the absence of perfect test coverage, verify the syntactical correctness of someone’s code is a big red flag. Syntax errors are caught by the compiler. Semantic errors aren't caught by the best type systems. At best, type systems are a way to encode a bit of the semantics so that the compiler can prove things about it. > To improve static type checking in Python, developers made libraries like jedi, pytype, mypy, and toasted-marshmallow, but they are often not used in most projects because they do not belong to the standard toolchain I can not imagine the author actually used jedi and believes this. That's... not how jedi works. I also don't know what to do with the argument of "oh, you have an optional static type system but people don't use it because it's annoying, this is why we should use a mandatory static type system" other than shrug. I like types! I think there are great arguments for types. I like the idea of being able to have a type system prove that certain bugs can't happen. This adds nothing but FUD and no new insights. [0]: https://danluu.com/empirical-pl/ https://danluu.com/empirical-pl/
mlthoughts2018 8y ago
> “In Python a good amount of errors are discovered at runtime" In my experience this is roughly equally true with statically typed languages as it is with Python. The types of errors the compiler helps find before running tests are just not important. They are not types of errors that matter much. And if compiler errors are cryptic enough, it can be a huge huge pain that you can’t just run the code on a toy input to see what’s going on. The whole pitch about how static typing and compilation will save you time by forcing more correctness prior to testing is just a hogwash myth in practice. It happens occasionally, but not nearly enough to justify all the stuff advocating it, and the benefits of being able to debug according to desired behavior and just not care about strict safety in edge cases you can guarantee you won’t hit are really tangible. You cannot easily dismiss these benefits.

by tln 8y ago

You're correct but this barely changes the authors points: "It’s virtually impossible to statically analyze" and "In Python a good amount of errors are discovered at runtime"

lvh 8y ago

The rest of the points are silly rehashes of arguments as old as Emacs v vim, but sure, let's go there too. We've done empirical research to see if this matters. Charitably, the results are "inconclusive"[0]. > The first glaring issue is that I have no guarantee that is_valid() returns a bool type. You can name functions ridiculous, unhelpful and misleading things in any language. The very fact that you know to expect a bool undermines the point: clearly, despite not having static types, a human managed to make a pretty reasonable assumption about what a piece of code was about to do. Just because the compiler can check that is_valid returns a string doesn't mean that hat's magically a useful thing to do. > The fact that I cannot, in the absence of perfect test coverage, verify the syntactical correctness of someone’s code is a big red flag. Syntax errors are caught by the compiler. Semantic errors aren't caught by the best type systems. At best, type systems are a way to encode a bit of the semantics so that the compiler can prove things about it. > To improve static type checking in Python, developers made libraries like jedi, pytype, mypy, and toasted-marshmallow, but they are often not used in most projects because they do not belong to the standard toolchain I can not imagine the author actually used jedi and believes this. That's... not how jedi works. I also don't know what to do with the argument of "oh, you have an optional static type system but people don't use it because it's annoying, this is why we should use a mandatory static type system" other than shrug. I like types! I think there are great arguments for types. I like the idea of being able to have a type system prove that certain bugs can't happen. This adds nothing but FUD and no new insights. [0]: https://danluu.com/empirical-pl/ https://danluu.com/empirical-pl/

mlthoughts2018 8y ago

> “In Python a good amount of errors are discovered at runtime" In my experience this is roughly equally true with statically typed languages as it is with Python. The types of errors the compiler helps find before running tests are just not important. They are not types of errors that matter much. And if compiler errors are cryptic enough, it can be a huge huge pain that you can’t just run the code on a toy input to see what’s going on. The whole pitch about how static typing and compilation will save you time by forcing more correctness prior to testing is just a hogwash myth in practice. It happens occasionally, but not nearly enough to justify all the stuff advocating it, and the benefits of being able to debug according to desired behavior and just not care about strict safety in edge cases you can guarantee you won’t hit are really tangible. You cannot easily dismiss these benefits.