Just because your statement confused me a little:

The type of brackets - {} - tells Perl that it's a hash.
The @ tells Perl to use list context vs. scalar context.

Note the difference between:

@hash{@array} = (1) x scalar(@array);
print join(" -- ", keys %hash), "\n";

#AND

$hash{@array} = (1) x scalar(@array);
print join(" -- ", keys %hash), "\n";
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