I am big fan of static analysis and would love to have the extra confidence & coherence that checked annotations provide. Some edx-platform’s more, uh, “magical” code (modulestore, the xblock runtimes, etc) would be a lot more approachable if correctly annotated.
With mypy, there’s going to be some up-front configuration and refactoring to get it to pass on edx-platform. Is it possible to start by checking a smaller piece of the project, and then working out from there? The new learning_sequences app could be a good candidate, being relatively new, well-documented, and partially annotated.
If we could get even a single directory passing, I would support a PR to add mypy to the edx-platform test suite (preferably as a GitHub action).