#!/usr/bin/perl -w
use strict;

open my $fh, '<', 'details.txt' or die $!;

until(grep !defined, my @details = map scalar <$fh>, 1 .. 4) {
    print @details, "\n";
}

##</code><code>##

#!/usr/bin/perl -w
use strict;

open my $fh, '<', 'details.txt' or die $!;

my $i;
my @details;

while(<$fh>) {
    push @details, $_;
    next if ++$i % 4;
    print @details, "\n";
    @details = ();
}

##</code><code>##

#!/usr/bin/perl -w
use strict;

open my $fh, '<', 'details.txt' or die $!;

sub read_lines {
    my ($fh, $amnt) = @_;
	return unless defined(my $line = <$fh>);
    return (
        $line,
        $amnt > 1 ? read_lines($fh, $amnt - 1) : ()
    );
}

while(my @details = read_lines($fh, 4)) {
    print @details, "\n";
}