The benefit of static typing isn't just reliability. Tooling is another major argument. Won't appeal to certain hardcore programmers who think that even notepad has too many features. But it is great for refactoring, finding all references to a function or a property or navigating through the code at design time. Basically all the features visual studio excels at for .net languages.

And I disagree with the barrier to entry argument. Static typing, by enabling rich tooling, helps a beginner (like it helped me) a lot more by giving live feedback on your code, telling you immediately where you have a problem and why, telling you through a drop down what other options are available from there, etc. Basically makes the language way more self-discoverable than having to RTFM to figure out what you can do on a class.

I think dynamic typing proponents get hung up on the auto-complete aspect. The real benefit is when you find someone writing a property with a common-ish name to a data structure and you want to know "who the hell uses this", you can answer that question pretty easy in statically typed languages. In dynamically typed languages you kind of just grep and hope the name is not too common.

> In dynamically typed languages you kind of just grep and hope the name is not too common.

For four days, I spent debugging a python production script because in one place I had typo'd ".recived=true" on an object and just couldn't understand why my state machine wouldn't work.

And very quickly, the whole team became fans of __slots__ in Python.

I still write 90% of my useful code in python, but that one week of debugging was exhausting & basically wouldn't have even compiled in a statically declared language. Even in python, the error is at runtime, after I got the __slots__ in place.

> I still write 90% of my useful code in python, but that one week of debugging was exhausting & basically wouldn't have even compiled in a statically declared language.[...]

nothing stops you from using static typing with python3

I haven't used optional typing in python. However, the problem I see with optional typing is that while I may choose to use it my team mates might not. Even more importantly, the 3rd party dependencies I use probably don't. So the amount of code that actually uses the types would be very limiting. Saying the choice is entirely up to you personally is a misnomer.

The typing spec provides for supplementary "stub files" that can be provided for third-party dependencies without their own annotations. The typeshed project provides these for a fair and quickly increasing number of common dependencies, and is plugged into pycharm and mypy by default: https://github.com/python/typeshed