I don't see how the Python 2 to Python 3 transition has been a "fiasco". It may not have been the fastest transition, but that really doesn't matter in practice.
Individuals and organizations with extensive Python 2.x software systems have been able to continue using those with no problems.
Development has been able to continue on Python 3.x without needing to worry about backward compatibility with Python 2.x. It is a cleaner language, in many ways.
Over time, we have indeed seen libraries, frameworks and users migrate from 2.x to 3.x as it benefits them. It's not something that's forced on them, causing disruption and anger.
And so we've gradually seen Python 3.x starting to become more and more adopted, while Python 2.x slowly fades away. It's a non-disruptive, steady transition.
If you want to talk about a real fiasco, Perl 6 is a much better example. Having no truly usable implementation after nearly 15 years, and thus basically no adoption, does qualify as a disaster in every sense.
True, Perl 6 is an amazing fiasco! Every bad thing in software has happened, so it's the world's most sensational counter-example! Stay away! Hide your kids!
P.S. But from close-up, it's the think-tank and test-bed of potential Perl 5 upgrades. Even if Perl 6 never ships, it's contributed tons of shipping code for Perl 5. Yes, it's hard to understand that from a distance, and it's not a PR dream, but oh well.
But from close-up, it's the think-tank and test-bed of potential Perl 5 upgrades.
I question this claim. Perhaps it's true of some syntactic features (`say` comes to mind as do some proposals for function signatures), but the semantics rarely translate over well (consider smartmatch). If you squint and tilt your head you can claim that Moose is an example of a feature designed in one language and implemented in another, but Moose is more an exercise in language/feature syncretism than it is porting something complete in implementation or design to Perl 5.
Individuals and organizations with extensive Python 2.x software systems have been able to continue using those with no problems.
Development has been able to continue on Python 3.x without needing to worry about backward compatibility with Python 2.x. It is a cleaner language, in many ways.
Over time, we have indeed seen libraries, frameworks and users migrate from 2.x to 3.x as it benefits them. It's not something that's forced on them, causing disruption and anger.
And so we've gradually seen Python 3.x starting to become more and more adopted, while Python 2.x slowly fades away. It's a non-disruptive, steady transition.
If you want to talk about a real fiasco, Perl 6 is a much better example. Having no truly usable implementation after nearly 15 years, and thus basically no adoption, does qualify as a disaster in every sense.