# And now the hardcore, nonobvious solution, leaving the grep
# loop prematurely and discarding the result :
$index = 0;
grep { goto DONE if ($_ eq $pos); $index++; 0 } @list;
DONE:
foreach $i (@list) {
  print( ("*"," ","|")[ 0 <=> $index-- ], " $i\n");
};