If that's what you need you need to either use a C style for or iterate over the array indices instead of the array itself.

for my $i ( 0 .. $#list ) { 
  $data->{"IS_LAST"} = $i < $#list ? 0 : 1;
  ## ...
}
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Another alternative would be to iterate over all items save the last and then process the last item seperately.

for my $item ( @list[ 0 .. $#list - 1 ] ) {
  process_item( $item, 0 );
}
process_item( $list[ $#list ], 1 );
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