What on earth is modern Perl? I tried asking my search engine. I got nothing that showed me examples of what the code looks like. Is there really a popular faction in the Perl community that's evolving the language in a different direction using modules?
http://modernperlbooks.com/books/modern_perl_2016/index.html ... seriously tho, if your search engine didn't at least link "modern perl" to somewhere in that site, something's very wrong with it. (edit: I see what you mean, it's thin on worked examples. I'd say browse around cpan for new uploads, most new perl code these days uses modern idioms)
The principles of modern perl pretty much boil down to "use the new stuff and turn off the old stuff":
* use strict and warnings, those go without saying. 'autodie' is also pretty much de rigueur these days too.
* disable legacy things like bareword filehandles and indirect object syntax.
* enable unicode everywhere by default in strings and I/O layers
* use Moose, or at least a compatible subset like Moo or Type::Tiny. This is probably the biggest differentiator of modern perl, as Moose is a major addition to the OO system, basically a backport of the perl 6 object system.
I wouldn't say the evolution of the language via modules is any kind of "faction", it's very much the mainstream thought of perl and always has been. Perl was designed from nearly the start to be hackable from within itself.
Moderl Perl is the recent versions of perl, like modern Java is the recent versions of Java. But Perl is more flexible providing forward compatibility.
For stability, Perl defaults to an old stable behavior. Modern features are opt-in
Perl::Modern is a handy way to select a version, sort of like Python's `from future import foo`