while (<>) {
    # ... process a chunk of input ...
    # ... print result ...
}

##</code><code>##

use strict;
use warnings;

my $input_layers = ':encoding(utf-8)';

if (!eof()) {
    binmode ARGV, $input_layers or die $!;
}
while (<>) {
    # ... process a chunk of input ...
    # ... print result ...
    if (eof && !eof()) {
        binmode ARGV, $input_layers or die $!;
    }
}

##</code><code>##

use strict;
use warnings;
use Iterator::Diamond;

my $iterator = Iterator::Diamond->new(magic => 'stdin');

while ($iterator->has_next) {
    my $line = $iterator->next;
    # ... process a chunk of input ...
    # ... print result ...
}