This is what made me give it a shot in TS, but the problem is your types at interface boundaries tend to be annoyingly complex. The other problem is any project

This is what made me give it a shot in TS, but the problem is your types at interface boundaries tend to be annoyingly complex. The other problem is any project with optional types soon becomes a project with required types everywhere. There might be more merit in widely-used public libraries, though. I don't make those.