gistfile1.txt

sub r2s (Rat $rat) {
    my $s = $rat < 0 ?? '-' !! '';
    my $r = $rat.abs;
    my $i = $r.floor;
    $r -= $i;
    $s ~= $i;
    if $r {
	$s ~= '.';
	my $place = 0;
	my %seen;
	while $r {
	    my $key = $r.perl;
	    if %seen.exists($key) {
		my $rep = $place - %seen{$key};
		$s = substr($s,0,*-$rep) ~ substr($s, *-$rep).subst(/(.)/, -> $/ { $0 ~ "\x0305" }, :g);
		last;
	    }
	    else {
		%seen{$key} = $place++;
		$r *= 10;
		$i = $r.floor;
		$s ~= $i;
		$r -= $i;
	    }
	}
    }
    $s;
}

say r2s(241025348275725.3352);
say r2s(1/7000);
say r2s(2**64 / 1 + 1/97);