Gradual typing

[akaihola]

Here's another stab at adding typing since #639 was closed.

I acknowledge that Paul has expressed that he isn't currently planning to add type hints, and that reviewing type hints would be a burden.

However, I believe this extremely minimal Mypy configuration and a minimal set of changes not only make Mypy pass, but also enable to use it to check some types, and allow development to continue without requiring full type hints everywhere.

Mypy takes over the burden of reviewing type annotations from humans.

Most notably, functions with no type hints are not checked by Mypy at all with this configuration. This allows adding type hints just only to select sections of the code base. It is still of course possible to gradually add typing overall and increase Mypy's strictness if desired.

See Using mypy with an existing codebase for more information.

[ruancomelli]

The type union syntax X | Y is only available in Python 3.10, but Aider still supports Python 3.9.
Instead, this should be

Suggested change

	repo_content_prefix: str | None = """Here are summaries of some files present in my git repository.
	repo_content_prefix: typing.Optional[str] = """Here are summaries of some files present in my git repository.

[akaihola]

On line 1 of this file, I've added

from __future__ import annotations

which makes sure X | Y is supported on Python 3.9.

[ryanpeach]

Need to put that in the tests too it looks like:

TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'

[nedtwigg]

I would think that typing an untyped python codebase is exactly the kind of thing that Aider itself would be great at. Typing the edges is trivial, that leads to type errors, fix those, that leads to new type errors, fix those, etc.

I also think if it's worth adding type annotations at all, then it's worth bumping to a Python version that supports the latest / greatest versions of them. Aider seems like more of an end-user thing than infrastructure library, seems okay for it to be more aggressive in bumping requirements than a typical library.

[Faolain]

Amazing work as this will make aider improving itself even better (from experience llms do quite well with typed code)

[CLAassistant]

All committers have signed the CLA.

[akaihola]

I rebased on main and fixed all typing errors which had appeared meanwhile. Also added a requirements file for running Mypy. It includes Mypy itself and some type stub packages. The workflow now uses this requirements file as well as other requirements files needed for type checking.

[ryanpeach]

Have you considered pyright instead? Pyright is fast enough to work in your vscode and neovim live, and can go in your pre-commit.

Also we should put typing into the github actions.

Personally I think typing will make aider better both in scripting mode (making it more understandable to devs, less likely for bugs) and for self-modification via aider (it will improve the linting loop, and will give more informative repo maps).

I'd definitely love to see a blog post about the accuracy of aider edits under properly typed vs untyped code generation.

[ryanpeach]

Very minimal IMO. I like it (though I have no authority)

[ryanpeach]

A few more lint comments

[ryanpeach]

Not sure why we need this on push, just PR right?

[ryanpeach]

Use a matrix like in the other workflows

[akaihola]

What's the benefit of running Mypy on other Python versions than the most recent supported one?

[ryanpeach]

ERROR: Cannot install None, aider-chat and aider-chat[browser,dev,mypy,playwright]==0.1.dev1+g1aa8de2 because these package versions have conflicting dependencies.

The conflict is caused by:
    aider-chat 0.1.dev1+g1aa8de2 depends on attrs==24.3.0
    aiohttp 3.11.11 depends on attrs>=17.3.0
    jsonschema 4.23.0 depends on attrs>=22.2.0
    referencing 0.36.0 depends on attrs>=22.2.0
    aider-chat[browser,dev,mypy,playwright] 0.1.dev1+g1aa8de2 depends on attrs==24.3.0
    aider-chat[browser,dev,mypy,playwright] 0.1.dev1+g1aa8de2 depends on attrs==24.3.0; extra == "browser"
    aider-chat[browser,dev,mypy,playwright] 0.1.dev1+g1aa8de2 depends on attrs==24.2.0; extra == "mypy"

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip to attempt to solve the dependency conflict

https://github.com/OnScale/aider-stateless/actions/runs/12914071198/job/36012781606?pr=7

[ryanpeach]

I've noticed a lot of dead code, dead variables, etc in the codebase.

I think this is from aider writing its own code a lot.

I think if we are going to have aider write its own code, strong linting is a necessity

[Faolain]

Completely agree here @paul-gauthier what are your thoughts?

[ruancomelli]

Don't forget to add from __future__ import annotations to the top of this file.