#!/usr/bin/perl

use Algorithm::Diff qw(traverse_sequences);
use Term::ANSIColor;
use strict;
use warnings;

my @from = split //, shift // 'this is the left string';
my @to = split //, shift // 'this is the right string';

traverse_sequences( \@from, \@to,
  {
  MATCH     => sub {print $from[shift()]},
  DISCARD_A => sub {print color('red'), $from[shift()], color 'reset'},
  DISCARD_B => sub {print color('green'), $to[pop()], color 'reset'},
  } );
print "\n";