For me the Perl 6 and Python 3 changes have similar problems: no realistic solution for massive code bases. I worked at least 3 different places that had massi

For me the Perl 6 and Python 3 changes have similar problems: no realistic solution for massive code bases. I worked at least 3 different places that had massive code bases in Perl 5, that saw no signs of changing the entire time. Furthermore, ecosystems develop around these things, e.g. people (unwisely or not) saving “data” as Perl 5 hashes. There are similar dependencies on the Python 2.x way of doing things. Also, every project has its own long-term maintenance items to do. LONG before I consider screwing with the very syntax of my entire code base, I will be thinking about things like: avoiding deprecated APIs in other libraries, refactoring problematic designs, etc. Also, project repositories frequently branch out and every merge is a pain point. There could be many people developing unrelated items in parallel. There is NO convenient place to merge in somebody’s completely new language syntax, just like there is no place for gratuitous reformatting of code or other high-impact, low-benefit scenarios. And finally, even if a code base isn’t massive, developers have limited time. It is always more attractive to fix some bugs or add dozens of features. It is never attractive to do a complete rewrite of code for unproven gain and definite pain.