use strict;
use warnings;

my $file1 = make_func (shift);
my $file2 = make_func (shift);

while (1) {
	my $line1 = $file1->();
	my $line2 = $file2->();
	last unless defined $line1 and defined $line2;
	print "$line1 $line2 \n";
}

sub make_func {
	my $file = shift;
	open my $FH, "<", $file or die "could not open $file $!";
	return sub 
		{my $c = <$FH>;  
		return unless defined $c; 
		chomp $c; 
		return $c
	}
}