It's pretty great, because you can run it in debug mode where it will assert-fail if your static type assertions are violated, or in optimized mode where those checks (and the code to support multiple types in a variable) go away and instead the program just blows up like a C program with a bad cast does.

For a lot of the business world, code flexibility is much more important than speed because speed is bottlenecked not on the architecture but on the humans in the process; your database queries going from two seconds to one second matters little if the human with their squishy eyeballs takes eight seconds to digest and understand the output anyway. But when the business's needs change, you want to change the code supporting them now, and types make it much easier to do that with confidence you aren't breaking some other piece of the problem domain's current solution you weren't thinking about right now (especially if your business is supported by a team of dozens to hundreds of engineers and they each have their own mental model of how it all works).

Besides... Regarding performance, there is a tiny hit to performance in Python for including the types (not very much at all, having more to do with space efficiency than runtime). Not only do most typed languages not suffer performance hindrance from typing, the typing actually enables their compilation-time performance optimizations. A language that knows "this variable is an int and only and int and always an int" doesn't need any runtime checks to confirm that nobody's trying to squash a string in there because the compiler already did that work by verifying every read and write of the variable to ensure the rules are followed. All that type data is tossed out when the final binary gets built.

It’s also a worst-of-both-worlds arrangement, in that you have to do the extra work to satisfy the type checker but don’t get the benefits of a compiled language in terms of performance and ease-of-deployment, and only partial benefits in terms of correctness (because the type system is unsound).

AFAIK the Dart team felt this way about optional typing in Dart 1.x, which is why they changed to sound static typing for Dart 2.

I’ve seen it many times. Here’s one of the more extreme examples, a highly-upvoted comment that describes not using type hints as “catastrophically unprofessional”:

https://www.reddit.com/r/Python/comments/1iqytkf/python_type...

Python typed or untyped feels like a taste / flexibility / prototyping tradeoff; TypeScript vs. JavaScript feels like "Do you want to get work done or do you want to wrap barbed wire around your ankle and pull?" And I say this as someone who will happily grab JS sometimes (for <1,000 LOC projects that I don't plan to maintain indefinitely or share with other people).

Plus, TypeScript isn't a strict superset of JavaScript, so choice at the beginning matters; if you start in JS and decide to use TS later, you're going to have to port your code.

If you're working on a project that doesn't use type hints, there's also plenty of frowning, but that's just because coding without a type checker is kind of painful.

"almost" is the load bearing word here, and/or a weasel word. Define what an "economically important project" is.

> Also just to be clear: node is filled with povertyware and you should be extremely careful what you grab from npm.

Is "povertyware" what we call software written by people and released for free now?