[ak217]

Monkey patching is a clear violation of the API contract and is expected to break when versions change.

It's really not clear to me how your claims can be backed up. Lack of static typing is a fundamental feature of Python, it's part of the design philosophy. The majority of the language functionality is built in the standard library, where modules and interfaces can be swapped out and deprecated easily. Modules in pypi can have different codebases for different interpreter versions, and programs/projects can declare their dependencies using virtualenv; multiple Python interpreter versions can coexist on the same system. Your claim boils down to saying that static typing allows languages to develop faster and cut down maintenance costs, but I don't think you can conclusively demonstrate either point.

[cmccabe]

virtualenv is a symptom of the disease, not the cure. People get stuff working with a specific version of all the libraries and of Python, and then they forget about upgrading. And why should they upgrade? It will just break their code in mysterious ways. It would be different if the compiler could tell them about changes in type signatures, but it can't.

In the real world, monkeypatching happens. And you may not always know that your libraries or framework are doing it, either. Ruby on Rails does extensive monkeypatching, even of core classes such as String. I don't think you can patch str in CPython due to implementation issues, but that's not the point.

[slurgfest]

Ruby's culture is FAR more tolerant of monkeypatching than Python's culture - monkeypatching str, for example, just isn't a thing you would do. So what constitutes 'the real world' differs between the two.