[nickm12]

I previously worked at Dropbox, which had server codebase consisting of over 2 million lines of (untyped) Python. While I was there, Dropbox introduced type annotations into the codebase and used it as a testing group for Mypy, which was being developed largely at Dropbox, with both Jukka Lehtosalo and Guido van Rossum on staff.

I can say from that experience that pretty much everything you are claiming is wrong. Developers were enthusiastic about adopting type annotations. We found it made code easier to understand, gave better support from IDEs, made refactors easier, and caught bugs earlier.

Type-checking that codebase with Mypy was a technical challenge, but the Mypy team did a tremendous amount of work scale Mypy through caching and other optimizations. It was still slow, taking minutes at times, but way faster than the complete test suite.

Now, I will be the first to tell you not to write a 2Mloc server in Python, but if you happen to have created one, type annotations are huge boon to making it work.

[ReflectedImage]

I've seen both the statically typed Python 1Mloc monolithic and the ducked typed 1Mloc micro-service based approach in practice.

I'm telling you the ducked typed micro-service based approach is the way to go.

But you sort of know that "not to write a 2Mloc server in Python", don't you? If we encourage developers to use static typing they will be writing 2Mloc monolithic servers. That's just the type of code that static typing encourages.

Encouraging static typing in Python is putting them down the path of disaster.

[nickm12]

Yes, I said quite clearly not to write a 2Mloc server in Python. Honestly, I would lean towards not writing servers of any size in Python, but if scalability and performance are of low concern, it could be a productive language for certain apps.

"If we encourage developers to use static typing they will be writing 2Mloc monolithic servers."

I don't even know where to begin with this wild assertion. Ill-advised as it was, Dropbox wrote its two million line server long before typed Python even existed. I wasn't around when they started cracking it up (see blog post below), but I strongly suspect the type annotations in the codebase helped rather than hindered that effort.

https://dropbox.tech/infrastructure/atlas--our-journey-from-...