Tomas Votruba has posted the second part of his Reactor series on his site today. In part one he covered some of the basics of the Ractor package (a CLI tool that provides some handy helper functions for Symfony applications). In part two he covers some of the "founding fathers" and packages that he built the package on top of.
You already know What Rector does and How it works from part 1.
It's not that PHP didn't need to be updated until 2017. I surely could delegate hundreds of upgrade-hours for my whole career. So why Now?
The post then talks about the idea of "codemod" functionality like the PHP CS Fixer that changes code to bring it up to PSR-2 compliance. It then covers the package that's one of the keys to the Reactor project, the nikic/PHP-Parser package. He talks about the read/write functionality, an example of a change it might make and finishes by thanking the "founding fathers" that made those packages available.