#!/usr/bin/perl -w
use strict;
use Text::Tabs;
use Symbol; #Symbol and
my @data;   #array instead of hash so the same file can be in several columns
my $sep ='';
if( $ARGV[0] =~ /^-sep/ ){
  (undef, $sep, @ARGV) = @ARGV;
}
die("usage: lam [-sep seperator] file1 file2 [...]\n") unless scalar @ARGV >1;
for(my $i=0; $i < scalar @ARGV; $i++){
  open($data[$i]->{FH}=gensym, $ARGV[$i]);
  $data[$i]->{w}=0;
  while(readline(*{$data[$i]->{FH}})){
    my $length = length(expand($_));
    $data[$i]->{w} = $length > $data[$i]->{w} ? $length : $data[$i]->{w};
  }
  $data[$i]->{h} = $.;
  seek($data[$i]->{FH}, 0, 0);
}
my $max = (sort {$main::b <=> $main::a} map {$_->{h}} @data)[0];
for(my $j=0; $j<$max; $j++){
  for(my $i=0; $i < scalar @ARGV; $i++){
    if( $j > $data[$i]->{h} ){
      print ' 'x$data[$i]->{w};
    }
    else{
      chomp($_ = readline(*{$data[$i]->{FH}}));
      $_ = expand($_);
      print $_, ' 'x($data[$i]->{w}-1-length);
    }
    print $sep unless $i+1 == scalar @ARGV;
  }
  print "\n";
}

##</code><code>##

#!/usr/bin/perl -w
use strict;
use Symbol;
use Text::Tabs;
die("usage: overlay file1 file2\n") unless scalar @ARGV == 2;
my @data;
for(my $i=0; $i < scalar @ARGV; $i++){
  open($data[$i]->{FH}=gensym, $ARGV[$i]) || die("overlay($ARGV[$i]): $!\n");
  1 while(readline(*{$data[$i]->{FH}}));
  $data[$i]->{LINE} = $.;
  seek($data[$i]->{FH}, 0, 0);
}
my $maxline = $data[0]->{LINE} > $data[1]->{LINE} ?
  $data[0]->{LINE} : $data[1]->{LINE};
for(my $i=0; $i < $maxline; $i++){
  if( $i > $data[0]->{LINE} ){
    while(readline(*{$data[1]->{FH}})){
      print;
    }
    last;
  }
  elsif( $i > $data[1]->{LINE} ){
    while(readline(*{$data[0]->{FH}})){
      print;
    }
    last;    
  }
  else{
    for my $data (@data){
        $data->{str} = readline(*{$data->{FH}});
        chomp($data->{str});
        $data->{str} = expand($data->{str});
    }
    my $maxchar = length($data[0]->{str}) > length($data[1]->{str}) ?
        length($data[0]->{str}) : length($data[1]->{str});
    my @onechars = split(//, $data[0]->{str});
    my @twochars = split(//, $data[1]->{str});
    my $str;
    for(my $j=0; $j<$maxchar; $j++){
      if( $j > $#onechars ){
        $str .= join('', splice(@twochars, $j));
      }
      elsif($j > $#twochars){
        $str .= join('', splice(@onechars, $j));
      }
      else{
        $str .= $onechars[$j] eq ' ' ? $twochars[$j] : $onechars[$j];
      }
    }
    print $str, "\n";
  }
}