use Math::Pari qw/ PARI /;
sub PARIdo {
    my $s = shift;
    $s =~ s/[{}\s]+//g;
    PARI($s);
}

##</code><code>##

PARIdo(q{
  mygcd(a, b) = {
    if (a > b, {
      mygcd(b, a);
    }, {
      if (a == 0, {
        b;
      }, {
        mygcd(b % a, a);
      });
    });
  }
});
print PARI("mygcd(12,8)");

##</code><code>##

my $v1 = PARI(12);
my $v2 = PARI(8);
print PARI(qq{mygcd($v1,$v2)});