If these had been available in Python 3.2 or even better 3.0, the switch would have been far easier for corporate users that need benefits before accepting the cost of change...
The usage is essentially the same, just a different command. Huge benefit though is that if you have Python 3.4+ installed you already have the virtual env and pip installed, so things are much simpler.
I'm not sure what the differences are to old virtualenv, but the biggest feature is that it works out of the box as long as you have Python > 3.4. No more googling "how to install virtualenv" or "easy_install pip; pip install virtualenv" stuff.
Unless you're on Ubuntu, where they ship a non-functional version of venv and require you to "sudo apt install" python-venv to get the working version, defeating the entire point of a simple module in the stdlib that lets you manage your Python environment as a user.
The big improvement on 16.04 is at least the error message explains what's going on.
You still need something like MyPy to actually validate types. What happened is that there's now a standard for typing annotations - now, PyCharm, MyPy, Wing IDE and anyone else can share the same syntax.
It's not only optional, it does nothing by default. What was introduced into python is a standardized way to do type annotations. It consists mostly of a new standard library module and as far as i know it doesn't even introduce changes to the language as it uses comments, additional files and the rarely used function annotations. The interpreter happily ignores them anyways but external tools like mypy don't have to invent their own incompatible syntax.
I was more excited about them when I believed they were actually enforced. I guess they help with static analysis in IDEs, but you can still get type errors at runtime, so Python is still missing out on the main advantage of static typing.
Because I'll need to support people that use it and explain it to newbies who read it. More work to do, without much benefit (to me; I understand it has much benefit to some people).
It's only without benefit if you don't write Python. Otherwise, it's like having tests that take almost no effort to write. What's not to love about it?
Edward Tufte might call it chart junk. It reduces the information to ink ratio. I generally get by just fine by choosing good names, so I don't need extra type checking beyond the standard duck typing.
"there is only one way to do things in Python" is just vapid marketing.
It's not even that, the actual quote is "There should be one, and preferably only one, obvious way to do things". The whole "there is only one way to do it" was a joke response to Perl's "There's more than one way to do it" motto.
I've had great experiences with optional static typing from tools like flow[1] and mypy. I've found you can gain most of the bug catching and readability benefits of static typing, while having the power of dynamic typing when come across a truly dynamic problem.
