extract-rat.p6

my $value = (1 - 0.00342) ** -0.5;
say $value;
say $value.Rat;
say extract-rat($value);

sub extract-rat(num $n) {
    my $buffer = Buf.allocate(8);
    $buffer.write-num64(0, $n);
    my $vi = $buffer.read-uint64(0);
    my $sign = $vi +> 63;
    my $exponent = ($vi +> 52) +& 0b11111111111;
    my $mantissa = $vi +& 0b1111111111111111111111111111111111111111111111111111;
    (-1) ** $sign * (1 + $mantissa / 2 ** 52) * 2 ** ($exponent - 1023)
}