[jrochkind1]

Ruby 1.8 to 1.9 was very painful, I am not sure why it was more succesful than Python 2->3, I'm not sure it "deserved" to be or was any less painful on it's face. It easily could have been just as disastrous. So also informed by that; ruby hasn't done anything nearly as painful since.

But that applies to making it so old code does not work in the new version of the language. Nobody expects all new code to work in the old version of the language. Ruby adds new features including syntax that won't properly parse in old interpreters all the time. It's not clear to me why inline type definitions couldn't be such.

[dragonwriter]

> I am not sure why it was more succesful than Python 2->3

Probably because Ruby had a much narrower area where it was heavily used, with fewer “finished” but critical libraries.

[riffraff]

Matz often cited the "carrot" of much better performance on 1.9 as a reason for the successful transition.

Python3 didn't offer much over python2, so people just saw the downsides, while ruby pushed people to upgrade with the promise that their efforts would gain them better performance and/or save money.

[Polylactic_acid]

I expect most ruby projects only have rails as its core dependency with all other gems being small utility libraries that can be easily updated and replaced. Python gets used for such a wide variety of things.

[baweaver]

That's definitely fair, and probably a large reason why they're so paranoid about repeating that.