Typing at scale: statically type-checking a large codebase
summary
Aiven moves a 2015 monorepo with about 200 developers from untyped Python toward static checking using mypy and a progressive-to-strict per-file scheme, then a generated inline-ignore script that lets the team flip to mostly-strict quickly. They hit a moving-target of mypy options and bugs, found any and deserialization break static guarantees (one production incident), augment with runtime guards/Pydantic, and conclude the approach works but needs tooling, conventions, and ongoing maintenance.
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chapters (7)
- 0:00Introduction to static typing
- 2:31Starting type annotation effort
- 7:28Progressive typing challenges
- 12:30Runtime vs compile-time checks
- 14:14Solving type-checking problems
- 22:09Would we do it again?
- 22:59Q&A session
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