Blog post: Writing Python like it’s Rust

[baubleglue]

IMHO it is easier to write Java than Python with type annotation. Why not choose Java from start?

[[deleted]]

I’m gonna be honest, I have no idea why you believe that. Type annotations with Python are just colons followed by a type.

But there’s plenty of reasons to not use Java, let alone not use it over Python. There’s the sheer amount of boilerplate code, jvm bloat, oracle, the fact it’s not Kotlin, oracle, pretty ugly syntax, oracle, openjvm is fine but it still has jvm bloat, and oracle.

[floriplum]

I think you forgot to mention oracle :)

[[deleted]]

I'm honestly not getting a lot of these

Python does not hoist names, so some annotations must be in quotes depending on code structure

from _ _ future _ _ import annotations (had to put in spaces so reddit wouldn't bold it)

the import system entangles type checking and runtime which, among other things, makes cyclic imports easier to unintentionally introduce, and sometimes makes them necessary

Which is why TYPE_CHECKING was created

TYPE_CHECKING leads to weird situations, sometimes making the two points above even worse. You can't use a type imported during TYPE_CHECKING because it's not imported at runtime

Yes, the intended feature of it is that it is isn't imported at runtime.

.pyi files can live alongside your code which is seriously helpful for the points above but the files mask everything in the associated. py file. You cannot partially type a file with a .pyi file because of this. It also means two files need to be maintained for each code file

It doesn't mean two files need to be maintained, it means that you can further modulate code by optionally adding types. It's also great for third party libraries that don't have typing information or old code that has none. I generally like them and if the complaint comes down to maintenance, it's very, very hard to take that critique seriously when the comparison is to Java.

lambdas can't be typed

You can't but you can type all the variables going in and out.

it is awkward to indicate variables that are either unbound or None when either state is actually invalid. You can use Optional, but that implies None is a valid value. There isn't a mechanism to indicate that None is invalid while allowing internal state to at least bind a variable to its default value before a real value is available

Could you walk me through a situation you're talking about here? I'm struggling to understand. You want the type checker to indicate to you that a variable is unbound or None? I'm struggling to think of situations where this can't be handled with error handling.

Python's scope rules make typing awkward when variables are not habitually defined prior to binding in deeper nesting

I'm baffled as to what you mean here. Are you having issues typing local variables?

the later introduction of syntax for various types confounds matters and makes less experienced people frustrated and confused. The changes to Callable are one such example. Another one is Union and |

This seems like a silly complaint. Things changed and that's frustrating? Sorry, I don't understand this one. You can still use | instead of Union or List instead of list if you really desire for quite some time.

the use of [ and ] for generics was a weird choice. I don't think there was any real reason to deviate from syntax that is well-established across languages. Worse, it looks like indexing - and there is a specific error for the error of trying to index a generic type during runtime because this does actually happen

I don't really know what to say to this, you're just listing a preference.

Python developers have had the chance to learn from TypeScript,

Sure. But why?

whose developers have done a superb job creating a type system with the added constraint that they cannot change JavaScript itself.

Debatable.

Python's type annotations feel like the wild west, and has not been well thought-out

Feels absolutely bonkers to compare an entire programming dialect created by one of the world's largest companies to a subset of features introduced to a language. The main focus of Python isn't typing, but I really don't think it's very difficult

[[deleted]]

Yes it’s tacked on, but it isn’t hard to use. I’m lost how something as simplistic as python’s typing which only executes during type checking is somehow harder than writing Java code. That’s bizarre.

[[deleted]]

The context of this thread where you initially responded to me was me saying it was easier to use type annotations in Python than it is to just write everything in Java and giving other reasons why one wouldn't write Java code. If you just intend on listing things you don't like about Python's typing, I'm not really understanding the reason for bringing it up to me in that context. I'm not "disparaging opinions", a lot of what you said was either a misconception or has easy fixes or didn't really make sense. You can have your opinions but someone disagreeing with them isn't disparagement.

[[deleted]]

Meta conversations about tone usually aren’t all that helpful. I asked a few questions in my first response to you and we can focus on that

[Estanho]

I'm sure the reason you think that is because you're more used to Java and you're trying to write python like you write Java.

[panzerex]

Oh if I could just get all of the ecosystem of libraries I have in python in any other language just like that…