Anonymous hashes & arrays, as you stated, are just hashes and arrays that don't have a name. They are only useful when used as a reference:

my $hashref  = { A => 1, B => 2 };
my $arrayref = [ 1, 2, 3 ];
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You would then access the elements of the references using ->:

print $hashref->{B}; # 2
print $arrayref->[2]; # 3
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or by

print %$hashref{B}; # 2
print @$arrayref[2]; # 3
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I much prefer ->, for what it's worth