Is there a difference between () and (())?

Is there a difference between ((),()) and (())?

What about {(),()} and {} and {()}?

I don't think there is any difference (i'm pretty confident).

You should look at perlfunc, expecially exists and defined.

## What about
$foo->{bar};         # no rules     # exists
$foo->{bar}={};      # all rules    # exists and defined
$foo->{bar}={ my => "# my rules" }; # exists and defined and has keys
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___crazyinsomniac_______________________________________
Disclaimer: Don't blame. It came from inside the void
perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"