[dathinab]

not specific to just your answer but why do people mention ruff?

Ruff is a linter which (intentionally) does close to no type checking.

So you pretty much have to pair it up with a type check to get any even just half way decent static code analysis.

[notatallshaw]

Because ty was built out of the ruff code base, and is maintained by the same team, and the type checking abilities are intended to help ruff with linting rules in the future.