pyre-check VS typing

Internally we use Pyre for Python type checking: https://github.com/facebook/pyre-check

Before type hinting, work had intense rules and linters enforcing docstrings with types. Now, type hints and automatic pyre runs take care of all the heavy lifting.

Python now has an optional type system and if you add one of them such as mypy or pyre to your CI process and you can configure GitHub to refuse the pull request until types are added you can make it somewhat strongly typed.

If you have a preexisting codebase I believe the way you can convert it is to add the types that you know on commits and eventually you will have enough types that adding the missing ones should be easy. For the missing ones Any is a good choice.

https://pyre-check.org and https://github.com/python/mypy are popular.

So to find things in a similar space, you need to look for languages with these sorts of constraints - so things like Sorbet for Ruby or pyright/pyre and you'll see similar and new ideas

Facebook/Instagram uses Pyre which is a typechecker for Python.

I'd be curious if the pyre-check compilation is any faster for you either by removing the inlining optimization flag (the `-Oclassic` here https://github.com/facebook/pyre-check/blame/36243764ab81a82...) or whether there's a way to compile pyre-check to bytecode instead of the native compilation step (which unfortunately it looks like there's no easy way to modify pyre-check's build config to do so).

I must be doing something wrong.

[1] https://github.com/facebook/pyre-check

Some other good alternatives for type checking are Pyright (which is seen in VSCode via Microsofts PyLance plugin) and Pyre.

but looking at relevant issues on GitHub it seems this has been shot down repeatedly. python/typing#18, python/typing#213

See https://github.com/python/typing/issues/256 for a discussion.

Mypy allows that because initial versions of PEP-484 allowed that. This has changed; here's the current wording on the PEP:

> This is no longer the recommended behavior. Type checkers should move towards requiring the optional type to be made explicit.

https://www.python.org/dev/peps/pep-0484/#id29

Dunno, other, larger projects than the one I'm working on seem to run up against this from time to time. (rasa_core, to pick one example from near the top of a Google search; also Telethon, Blender, TensorFlow, Pandas. Guido also filed a bug on the typing module in an early version of Python 3.5 because of unexpected implications of this particular issue, so the problem isn't exactly purely theoretical.) That's aside from the wish for conceptual purity in the call signatures of classes and their subclasses, which is not always and automatically a bad wish to have; and the notion that a language that prides itself on its introspective faculties might want to make introspection of classes from the top of a class hierarchy possible, at least in theory? Perhaps to facility learning about the language and/or visualizing large class hierarchies easily, for instance?

How do you define Python? If you include PEP 484 in your definition, surely it must be 'statically typed', otherwise there would be no need for these terms.

Since Python 3.5 (PEP-484), developers can add type annotations to their code. Python's optional static typing improves code comprehension, code completion, program analysis, and more. However, retrofitting type annotations can be a laborious and time-consuming task.

You might be interested in looking at PEP 484 (Type Hints https://www.python.org/dev/peps/pep-0484/) and PEP 483 (The Theory of Type Hints https://www.python.org/dev/peps/pep-0483/).

> Similarly where a language with first-class support for types might have `type Foo`, Python makes you write `T = TypeVar("T"); class Foo(Generic[T])` or something like that, and it gets more confusing when you only want one of the methods to be generic and I can never remember whether that `T` takes on a single type across all uses or which scope I need to define it in, etc.

I don't know about you but I find PEP 484 very clear here: https://www.python.org/dev/peps/pep-0484/#scoping-rules-for-...

> The problems for which I'm less optimistic tend to revolve around shoehorning typing into existing Python syntax--e.g., to get a callback that takes kwargs you have to define a protocol with a `__call__` method that takes kwargs because you can't express it with `typing.Callable`

You might be interested in the discussion over here then -> https://github.com/python/typing/issues/769#issuecomment-741...