Fewer moving parts. 
sub gcd {
  my ($n, $m) = @_;
  $m ? gcd($m, $n%$m) : $n;
}

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But is worrying about this a false path?

In reply to Re: Re: Euclid's Algorithm: A Homage to Tilly by Anonymous Monk
in thread Euclid's Algorithm: A Homage to Tilly by ignatz

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