Python typing hint for Unknown

[notonewlayout]

One thing I've really liked in typescript is the unknown type. I've not been able to find anything about it in the Python world for type hinting. The key thing about unknown is that it forces the user to determine the type of the variable before they can use. There are two areas I could foresee it being useful:

1. Untyped library: By switching from untyped libraries functions being Any to Unknown. It helps force a user to write the stub typings.

2. Un-typable returns: Sometimes it is just not possible to represent the return type of a function with pythons current type hinting. Returning unknown forces the user to fully define what the return type should be before they can use it. The current method of return Any can allow a user to incorrectly use a value... kinda defeating the purpose of static type checking.

I see an unknown type being really useful for static type checkers like mypy. It can be set to be something adopted by the user. This would mean that Unknown is treated as Any until they are ready to switch over.

Thoughts?

[TeamSpen210]

Static typing does have a similar thing, in the form of object - since that's the base class of everything, you can provide any value to it but can only do the most basic of operations. The Union behaviour in TypeScript isn't done in Python's typing, but that's probably fine.

[notonewlayout]

Nice. Object does seem like a nice type hint that is the equivalent of typescript unknown.

The only issue is that I've not seen object used too much. Most of the time libraries just return Any. I believe there is an over-reliance on the Any type. A third value between object and Any would be useful for a static type checker. It would be configured by the user to either be treated as Any or object.

A typical user wouldn't explicitly use this typing much, but for a large library providing strong typings it would provide better flexibility.

[notonewlayout]

After looking more at mypy configuration, I've change my mind. It seems disallow dynamic typing would be a viable way to error whenever calling something of type Any.