mypy VS pyright

It's got type annotations and mypy has a discussion about it here as well: https://github.com/python/mypy/issues/1282

There is already an AOT compiler for Python: Nuitka[0]. But I don't think it's much faster.

And then there is mypyc[1] which uses mypy's static type annotations but is only slightly faster.

And various other compilers like Numba and Cython that work with specialized dialects of Python to achieve better results, but then it's not quite Python anymore.

[0] https://nuitka.net/

[1] https://github.com/python/mypy/tree/master/mypyc

In Python there is MyPy that can help with this. https://www.mypy-lang.org/

It's funny you should say this.

Reading this article prompted me to future-proof a program I maintain for fun that deals with time; it had one use of utcnow, which I fixed.

And then I tripped over a runtime type problem in an unrelated area of the code, despite the code being green under "mypy --strict". (and "100% coverage" from tests, except this particular exception only occured in a "# pragma: no-cover" codepath so it wasn't actually covered)

It turns out that because of some core decisions about how datetime objects work, `datetime.date.today() < datetime.datetime.now()` type-checks but gives a TypeError at runtime. Oops. (cause discussed at length in https://github.com/python/mypy/issues/9015 but without action for 3 years)

One solution is apparently to use `datetype` for type annotations (while continuing to use `datetime` objects at runtime): https://github.com/glyph/DateType

PEP 695 is great. I've been using mypy every day at work in last couple years or so with very strict parameters (no any type etc) and I have experience writing real life programs with Rust, Agda, and some Haskell before, so I'm familiar with strict type systems. I'm sure many will disagree with me but these are my very honest opinions as a professional who uses Python types every day:

* Some types are better than no types. I love Python types, and I consider them required. Even if they're not type-checked they're better than no types. If they're type-checked it's even better. If things are typed properly (no any etc) and type-checked that's even better. And so on...

* Having said this, Python's type system as checked by mypy feels like a toy type system. It's very easy to fool it, and you need to be careful so that type-checking actually fails badly formed programs.

* The biggest issue I face are exceptions. Community discussed this many times [1] [2] and the overall consensus is to not check exceptions. I personally disagree as if you have a Python program that's meticulously typed and type-checked exceptions still cause bad states and since Python code uses exceptions liberally, it's pretty easy to accidentally go to a bad state. E.g. in the linked github issue JukkaL (developer) claims checking things like "KeyError" will create too many false positives, I strongly disagree. If a function can realistically raise a "KeyError" the program should be properly written to accept this at some level otherwise something that returns type T but 0.01% of the time raises "KeyError" should actually be typed "Raises[T, KeyError]".

* PEP 695 will help because typing things particularly is very helpful. Often you want to pass bunch of Ts around but since this is impractical some devs resort to passing "dict[str, Any]"s around and thus things type-check but you still get "KeyError" left and right. It's better to have "SomeStructure[T]" types with "T" as your custom data type (whether dataclass, or pydantic, or traditional class) so that type system has more opportunities to reject bad programs.

* Overall, I'm personally very optimistic about the future of types in Python!

[1] https://github.com/python/mypy/issues/1773

# is fixed: https://github.com/python/mypy/issues/12987.

You probably already know but you can add type hints and then check for consistency with https://github.com/python/mypy in python.

Modern Python with things like https://learnpython.com/blog/python-match-case-statement/ + mypy + Ruff for linting https://github.com/astral-sh/ruff can get pretty good results.

I found typed dataclasses (https://docs.python.org/3/library/dataclasses.html) in python using mypy to give me really high confidence when building data representations.

Pyright is a fast type checker meant for large Python source bases. It can run in a “watch” mode and performs fast incremental updates when files are modified.

However, I made it faster for my use-case by changing some settings. Neovim allows to have these settings in the setup function for LSP. I was trying to figure out how do I change these settings with doom emacs. Pyright docs suggest to have these settings in pyrightconfig.json.

Not exactly what you are looking for but maybe useful to others.

https://github.com/microsoft/pyright/blob/main/docs/mypy-com...

You can use pyright instead[0]. It is the FOSS version of pyright, but having some features missing.

[0]: https://github.com/microsoft/pyright

Unfortunately, pyright explicitly stated that they are not interested in inlay hints or other language server features, that those will only be added to pylance. That's why I added it myself instead of submitting a pull request to pyright. See https://github.com/microsoft/pyright/issues/4325

return { -- add pyright to lspconfig { "neovim/nvim-lspconfig", ---@class PluginLspOpts opts = { ---@type lspconfig.options servers = { -- Listed servers will be automatically loaded to buffers jsonls = { settings = { json = { format = { enable = true, }, }, validate = { enable = true }, }, }, pyright = { settings = { python = { analysis = { -- https://github.com/microsoft/pyright/blob/main/docs/settings.md autoSearchPaths = false, useLibraryCodeForTypes = true, diagnosticMode = "openFilesOnly", }, }, }, }, }, -- Add folding capability to use LSP for ufo plugin capabilities = { textDocument = { foldingRange = { dynamicRegistration = false, lineFoldingOnly = true, }, }, }, }, }, }

[{ "resource": "/Documents/Coding/VSCode/Projects/Photoeditor/PhotoEditor.py", "owner": "_generated_diagnostic_collection_name_#0", "code": { "value": "reportMissingModuleSource", "target": { "$mid": 1, "external": "https://github.com/microsoft/pyright/blob/main/docs/configuration.md#reportMissingModuleSource", "path": "/microsoft/pyright/blob/main/docs/configuration.md", "scheme": "https", "authority": "github.com", "fragment": "reportMissingModuleSource" } }, "severity": 4, "message": "Import \"requests\" could not be resolved from source", "source": "Pylance", "startLineNumber": 2, "startColumn": 8, "endLineNumber": 2, "endColumn": 16 }]

I don't use astro, but you can configure pyright by using a pyrightconfig.json or directly in the LSP configuration.

I prefer jedi over pyright as pyright has crippled documentation support outside of VSCode. I also found jedi is make correct suggestions based on inferred type in some situations where pyright would need type annotation to provide completions, pyright is significantly faster though. Jedi with mypy and flake8 is comparable to pyright I think, but unfortunately mypy wasn't working over tramp. Also isort wasn't working over tramp, but jedi, black, importmagic and flake8 all worked.