#!/usr/bin/perl
use strict;
use warnings;

sub make_file_chunker {
    my ($fh, $n) = @_;
    my $eof = 0;
    return sub {
       # Don't try to read past EOF.
       # This matters for terminals.
       return if $eof;

       my @chunk;
       for (1..$n) {
          my $line = <$fh>;
          if (!defined($line)) {
             $eof = 1;
             last;
          }

          chomp($line);
          push @chunk, $line;
       }

       return @chunk;
    };
}

my $iter = make_file_chunker($fh, 4);
while ( my @chunk = $iter->() ) {
   print(join("\n", @chunk) . "\n\n");
}