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# Parens, not curlies
my %hash = (this => "one", that => "two"); 
# Use a slash when dumping @var or %var
print Dumper(\%hash);
print($hash{this}, "\n");
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Curlies create an anonymous hash and return a reference to that hash. Hashes are initialized from a list, not from a hash reference. Use parens (not curlies) to create a list.

If you wanted to work with a hash reference, use curlies, and assign the result of the curlies to a scalar.

my $hash = { this => "one", that => "two" }; 
print Dumper($hash);
print($hash->{this}, "\n");
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