• Boolean operations apply a boolean context
• Undefined values are treated as false
• Scalars are evaluated as booleans
• Numbers are evaluated as true if non-zero
• Strings are evaluated as true if non-empty
• Lists are evaluated as booleans
• Lists, arrays, and hashes are evaluated as true if non-empty

        my $string;
        if ($string) {
            print "A: Hello, $string.\n";
        }

        $string = "world";
        if ($string) {
            print "B: Hello, $string.\n";
        }
      

        B: Hello, world.