Hints don't provide any guarantees. It's still possible to silently and unknowingly pass the wrong type of value into any given argument, with or without the checker. The "tooling" the other languages have includes a compiler that performs these checks in a way that Hints + Checker-of-choice is unlikely (or unable) to. "What do you think these checkers do?" you might ask. The answer is: not nearly what a compiler does.
> It's still possible to silently and unknowingly pass the wrong type of value into any given argument
This is also possible in traditionally statically typed languages. Nothing stops you from doing unsafe casts or using reflection. Much like its exceedingly unlikely that you'll run across this in "normal" java or C++, its exceedingly unlikely for you to run into any issues with this in python. And, in fact, the typechecker has ways to handle unusual things like dynamically created attributes, for when that comes up.
And yes I mean this quite honestly. I've seen a lot of typechecked code, some of it quite ridiculously dynamic. Typecheckers perform absolutely fine.
>The "tooling" the other languages have includes a compiler that performs these checks in a way that Hints + Checker-of-choice is unlikely (or unable) to.
What way is that? Typechecking is static analysis. There's really no difference between how java or cpp does typechecking and how mypy does, other than that the python typechecker isn't installed by default.
> This is also possible in traditionally statically typed languages. Nothing stops you from doing unsafe casts or using reflection.
Neither of those is "silent" or "unknowing".
> What way is that? Typechecking is static analysis. There's really no difference between how java or cpp does typechecking and how mypy does, other than that the python typechecker isn't installed by default.
The typechecker can't handle un-hinted code (or, rather, it chooses something very permissive, like 'Any' for all hints). It's incomplete at best.
> This is not an answer.
It is. That you don't like or agree with it doesn't make it not an answer.
And in Java or c++, un-hinted code couldn't compile. The python type checker can do more than a java or c++ checker in this regard.
>Neither of those is "silent" or "unknowing".
They're exactly as silent or unknowing as you would get in typed python code. You appear to be comparing untyped python. That's an incorrect comparison. Offhand, I actually can't think of anything I could do in typed python that would get around the type checker, that wouldn't be considered reflection or a dynamic cast, and be very obviously so in python too. If you have an example of a silent or unknowing failure of well typed python code that passes on mypy, you should probably file a bug report ;)
>That you don't like or agree with it doesn't make it not an answer.
You're right. Its not an answer not because I disagree with it (I don't), but because it doesn't actually answer anything, which is why I don't disagree with it.
To summarize this:
Python typecheckers are capable of more type inference than Java, and require less syntax than c++ or Java to get well typed code. A typed python codebase can interact cleanly with an untyped python codebase, and within the typed parts of the code, you get equivalent safety guarantees to what the type systems of Java or C++ provide.
Your appear to be ascribing magical powers to compilers in other languages, when those compilers have exactly the same type information as mypy does.
In other words, going back to your first statement:
>Hints don't provide any guarantees.
Hints provide exactly the same guarantees as any other type system: "Assuming you write reasonable code that doesn't attempt to subvert the type system, the type system will catch any dumb mistakes you make."
That's the exact same guarantee you get in any statically typed language.
