The feature pragma has one problem - it comes with Perl itself, so it does not inform you about features in higher versions of Perl.

feature pragma is pure perl, all it does is twiddle $^Hints, so it can be dual-lived , it should be dual lived , so this problem not much of a problem

sure, Syntax::Construct can be like Modern::Perl and other $^Hints-twiddlers ...

but there is a benefit to having CORE modules that already handle this fundamental operation, both documenting and turning on features, actually do both things and do them well, its called feature after all ...

so it doesn't really need to turn on //= but it can document it  use feature qw[ // ]

you see what I'm getting at, right? perlver is great for finding stuff out, feature is great for documenting and turning it on ... one place to look information, same old vocabulary , perldoc feature

if you keep vocabulary small, and not have 11teen different names for the same thing ...

Syntax::... a new top level namespace that doesn't scream this is about core perl language features ...

This is the general idea