RosettaCodeData/Task/Arithmetic-geometric-mean/Perl-6/arithmetic-geometric-mean-2.pl6

sub agm( $a, $g ) {
    $a ≅ $g ?? $a !! agm(|@$_)
        given ($a + $g)/2, sqrt $a * $g;
}

say agm 1, 1/sqrt 2;