chore: type annotations - convert uses of Optional and some Union usage to union operator |

[edmondchuc]

This PR is a follow-up to #2963. Largely, it updates usages of typing.Optional and typing.Union type annotations to the more modern and preferred union operator |.

Some other notes:

• Some w3c sparql10 tests now passing, but not sure how. Results from the earl report has changed.

Summary of changes

Checklist

• Checked that there aren't other open pull requests for
  the same change.
• Checked that all tests and type checking passes.
• If the change adds new features or changes the RDFLib public API:
  • Created an issue to discuss the change and get in-principle agreement.
  • Considered adding an example in ./examples.
• If the change has a potential impact on users of this project:
  • Added or updated tests that fail without the change.
  • Updated relevant documentation to avoid inaccuracies.
  • Considered adding additional documentation.
• Considered granting push permissions to the PR branch,
  so maintainers can fix minor issues and keep your PR up to date.

[coveralls]

coverage: 90.248% (-0.001%) from 90.249%
when pulling 1e36c39 on edmond/types
into 4ea72ac on main.

[ashleysommer]

@edmondchuc
Did you need to fix any typing errors that arose from these changes and needed to be fixed? I expect if they are all simply replacing Union and Optional with their alternate forms, then MyPy should not have generated any new errors.

Something else to note, on the topic of Optional[X] vs X | None personally I prefer the former. Even though now the Python developers discourage its use and advocate to use the | None form, I personally tend to still use Optional[] in my projects, as a matter of personal taste. I think its because it reminds me of the Rust Option<> type.

[edmondchuc]

I didn't run into any mypy errors. No runtime changes and no semantic changes to the codebase.

Something else to note, on the topic of Optional[X] vs X | None personally I prefer the former. Even though now the Python developers discourage its use and advocate to use the | None form, I personally tend to still use Optional[] in my projects, as a matter of personal taste. I think its because it reminds me of the Rust Option<> type.

Yeah, that's fair. I definitely was tossing up between the two, but the python docs helped me over the line given that their official stance is to prefer the union operator now.

For others reading this. From the python typing docs:

To define a union, use e.g. Union[int, str] or the shorthand int | str. Using that shorthand is recommended.

Keep in mind that Optional is shorthand for Union.

Optional[X] is equivalent to X | None (or Union[X, None]).