My question is, given the two lists above, how would you create $x without those other temporary variables?

Taking you literally that the values (@data array already exists, just autovivify the hashref: 

my $r;
@{ $r }{ 1 .. 12 } = @data;

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In reply to Re: On-the-fly hashref by BrowserUk
in thread On-the-fly hashref by oko1

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