in reply to sorting domains by extention

In this specific case, you don't need a fullblown GRT. Of course the simpler approach is less efficient, but you won't notice that before you start sorting tenthousands of domains, and I find the simpler approach is tons more readable. 
my @sorted_domain =
    map { join ".", reverse split /\./ }
    sort
    map { join ".", reverse split /\./ }
    @domain;

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 Argh. I'm not paying attention.

Makeshifts last the longest.

In Section Seekers of Perl Wisdom