gistfile1.txt

C:\consulting\rakudo>perl6 -I. -MPrev
> 1 + 2
3
> 2 * prev
6
> 3 * prev
18

Prev.pm6

my Mu $prev;
sub prev() is export { $prev }
my $comp := nqp::getcomp('perl6');
$comp.HOW.add_method($comp, 'autoprint', method (Mu \value) {
    $prev := value;
    self.interactive_result(value)
        unless nqp::tellfh(nqp::getstdout()) > $*AUTOPRINTPOS;
});
$comp.HOW.compose($comp);