> Count me in the "don't make breaking changes" camp. You can spit out warnings to prevent developers from using certain language features in new code, but chan

> Count me in the "don't make breaking changes" camp. You can spit out warnings to prevent developers from using certain language features in new code, but changes which outright break old code should be extremely rare. "Extremely rare" != "never". > This is how Javascript works (the language, not the ecosystem around it), and it means I can update my web browser and continue visiting old websites. ...and there are reasons for this which don't apply to Python. A typical JavaScript deployment needs to run on millions of machines which the developer doesn't control, and coordinating an update of a JavaScript version to all the machines it needs to run on isn't feasible. Python is usually not run under these constraints: in the typical case, Python runs on servers which the person running it on controls. JavaScript pays an extremely high cost for this, continuing to support decades-old horrible misfeatures such as nonsensical typecasts, returning undefined from nonexistent members, and a variety of incompatible ways to make asynchronous calls. You shouldn't do this unless you have a very strong reason to do so, and these misfeatures is one of the main reasons you shouldn't use JavaScript unless you have a strong reason to do so.