Well, no. They are not certainly using int, they might be using a more efficient data type.
This might be for legacy reasons or it might be intentional because it might actually matter a lot. If I make up an example, chat_participant_id is definitely stored with each message and probably also in some index, so you can search the messages. Multiply this over all chats on WhatsApp, even the ones with only two people in, and the difference between u8 and u16 might matter a lot.
But I understand how a TypeScript or Java dev could think that the difference between 1 and 4 bytes is negligible.
Just because we cannot prove something, doesn't mean that we can treat strong claims the same way as proven hypnosis. If we cannot prove that UBI is overall beneficial, we just cannot believe it with the same certainty that we would if we had a bunch of studys on our side.
Look, I'm not saying that we have nothing - I'm just saying that what we have are educated guesses, not proven facts. Maybe "open question" was too strong of a term.
Well, you can conclude anything using your reasoning, but that does give the high degree of certainty that is sought after in the studies reviewed in the article.
Again, I'm not saying that I don't believe static type checkers are beneficial, I'm just saying we cannot say that for sure.
It's like saying seat belts improve crash fatality rates. The claim seems plausible and you can be a paramedic to see the effects of seat belts first-hand and form a strong opinion on the matter. But still, we need studies to inspect the impact under scrutiny. We need studies in controlled environments to control for things like driver speed and exact crash scenarios, we need open studies to confirm what we expect really is happening on a larger scale.
Same holds for static type checkers. We are paramedics, who see that we should all be wearing seat belts of type annotations. But it might be that we are some subset of programmers dealing with problems that benefit from static type checking much more than average programmer. Or there might be some other hidden variable, that we cannot see, because we only see results of code we personally write.
My conclusion is that it is hard to empirically prove that "static type systems improve developer productivity" or "STS reduce number of bugs" or any similar claim. Not because it looks like it is not true, but because it is hard to control for the many factors that influence these variables.
Regardless of anyone's opinion on static/dynamic, I think we still must call this an "open question".
My laptops runs postgres, but it is still pretty portable