Guido van Rossum

Some type checkers also include a bunch of experimental ideas that aren't official standard Python syntax yet.

The static type checkers also just get better at discovering

things that sort of are unspecified by the language, but that sort of could make sense.

And so each static type checker actually has its sort of strong and weak points.

And you see that everywhere, right?

Because there's not one single JavaScript engine either.

There is one in Chrome.

There is one in Safari.

There is one in Firefox, right?

I can't put a number on it, but from the number of packages that do interesting things with it at runtime and the fact that there are like...

Now, three or four very mature type checkers that each have their segment of the market.

And then there is PyCharm, which has a sort of more heuristic-based type checker that also supports the same syntax.

My assumption is that...

Many, many people developing Python software professionally for some kind of production situation are using a static type checker.

Especially anybody who has a continuous integration cycle probably has...

one of the steps in their testing routine that happens for basically every commit is run a static type checker.

And in most cases, that will be MyPy.

So I think it's a pretty popular topic.

Historically, I actually started out with using Vim, but when it was still called VI.

For a very long time, I think from the early 80s to... I'd say two years ago, I was an Emacs user.