You can completely skip this appendix and the experimental features we show and not suffer for it. Or you can blindly follow the examples we show in the chapters and not worry about what is happening. But we think you’ll want to use them and understand them because we want to use and understand them too.
Many of the new features in Perl aren’t really “new.” They’re experimental. You have to do something to enable them, they might change, and they might disappear altogether. In fact, v5.24 removed two experimental features.
This is quite clever. People can install the latest perl and start using these new features. They can test them, see how they interact with other features, and best of all, develop unexpected idioms for them. Or they can completely ignore them and not worry about backward compatibility. The Perl 5 Porters, the people who develop and maintain the Perl code base, get to see how people use and react to a feature before they commit to making it permanent.
Learning Perl should show you the best and most exciting ways of working in Perl, but we also don’t want you to rely on experimental features that might disappear a year after you buy this book. We show you some of the new features, but when we do, we point to this appendix so you can get the background we don’t want to explain each time.
feature module documentation lists most of the new features and gives a brief
description of their use. You can also read the perldelta documentation ...