feat: add type checking to backend codebase (ty, mypy)

[kshitijrajsharma]

add mypy static code checks !

[linear]

TECH-948

[spwoodcock]

https://github.com/astral-sh/ty

Let's see what happens to Astral over time, but as long as their tools keep being open-sourced, this is a good replacement =)

[kshitijrajsharma]

https://github.com/astral-sh/ty

Let's see what happens to Astral over time, but as long as their tools keep being open-sourced, this is a good replacement =)

Indeed , i use ty regularly! Thanks sam , this issue should be updated to use ty

[spwoodcock]

I've also addressed this in other repos in the past, like FieldTM. My conclusion was that adding a type checking pre-commit hook was a huge undertaking - there could be 1000s of corrections to make in a repo 😆

One option these days could be to use an LLM to refactor - but it's a huge refactor with a lot of manual review.

The second best option is to add good linting / formatting (ruff), but then for type checking ask the user to ensure their IDE has it in place. Any underlined / highlighted issues in the IDE should ideally be fixed before commit. (vscode for example has mypy integrated using the Python extension. Perhaps there is a way to add ty to vscode too)

[kshitijrajsharma]

I've also addressed this in other repos in the past, like FieldTM. My conclusion was that adding a type checking pre-commit hook was a huge undertaking - there could be 1000s of corrections to make in a repo 😆

One option these days could be to use an LLM to refactor - but it's a huge refactor with a lot of manual review.

The second best option is to add good linting / formatting (ruff), but then for type checking ask the user to ensure their IDE has it in place. Any underlined / highlighted issues in the IDE should ideally be fixed before commit. (vscode for example has mypy integrated using the Python extension. Perhaps there is a way to add ty to vscode too)

I bet ! Haha which is why i haven't added ruff and ty into backend yet ! Probably one day to blindly format all the files and add it to hooks ! Yes ty is available in vscode !

[spwoodcock]

Seems to be! https://marketplace.visualstudio.com/items?itemName=astral-sh.ty