One lunch I was complaining about how or and die get all of the good work and some of my bit-twiddling coworkers said that they hardly ever have anything to do. We went out for drinks later and they tried to teach me what they know about integers. I find it very hard to understand but I think I figured out how to do 2+2.

sub add {
    my( $a, $b, $bit, $cary, $sum ) = ( @{$_[0]}, 1, 0, 0 );
    $sum |= $bit   if  1 & ( $a ^ $b ^ $cary );
    $cary = 1 & ( $a & $b | ( $cary & ($a|$b) ) );
    return $a | $b ? [$a>>1,$b>>1,$bit<<1,$cary,$sum] : $sum;
}
my @args = map {0+$_} (@ARGV,2,2)[0,1];
my $acc = add( [@args] );
$acc = add($acc)   while  ref $acc;
print "add[@args] = $acc\n";
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