#!/usr/bin/perl

# http://perlmonks.org/?node_id=1174957

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

my $template = <<END;
The earliest conceptualization of human rights is credited to ideas about natural rights emanating from natural law. In particular, the issue of universal rights was introduced by the examination of extending rights to indigenous peoples by Spanish clerics, such as Francisco de Vitoria and Bartolomé de Las Casas. In the Valladolid debate, Juan Ginés de Sepúlveda, who maintained an Aristotelian view of humanity as divided into classes of different worth, argued with Las Casas, who argued in favour of equal rights to freedom from slavery for all humans regardless of race or religion. 
END

my $copywitherrors = <<END;
The earliest conceptulization of human rights is credited to ideas about rights emanating from natural law. In particular the issue of universal rights was introduced by extending rights to indigenous peoples by Spanish clerics, such as Francisco de Vitoria and Bartolomé de Las Casas. In the Valladolid debate, Juan Ginés de Sepúlveda, who maintained an Aristotelian view of humanity as divided into clases of different worth argued with Las Casas, who argued in favour of equal rights to freedom from slavery for all humans regardless of race.
END

my $somethingelse = <<END;
Although ideas of rights and liberty have existed in some form for much of human history, there is agreement that the earlier conceptions do not closely resemble the modern conceptions of human rights. According to Jack Donnelly, in the ancient world, "traditional societies typically have had elaborate systems of duties... conceptions of justice, political legitimacy, and human flourishing that sought to realize human dignity, flourishing, or well-being entirely independent of human rights. These institutions and practices are alternative to, rather than different formulations of, human rights".14 The history of human rights can be traced to past documents, particularly Constitution of Medina (622), Al-Risalah al-Huquq (659-713), Magna Carta (1215), the Twelve Articles of Memmingen (1525), the English Bill of Rights (1689), the French Declaration of the Rights of Man and of the Citizen (1789), and the Bill of Rights in the United States Constitution (1791) 
END

sub compare
  {
  my ($old, $new) = @_;
  my $changes = 0;

  traverse_sequences( [ split //, $old ], [ split //, $new ],
    {
    DISCARD_A => sub { $changes++ },
    DISCARD_B => sub { $changes++ },
    } );
  return $changes;
  };

my $length = length $template;
print "length: $length\n";

my $answer = compare($template, $copywitherrors);
my $ratio = $answer / $length;
printf "copywitherrors: %d  ratio %.3f\n", $answer, $ratio;

$answer = compare($template, $somethingelse);
$ratio = $answer / $length;
printf "somethingelse: %d  ratio %.3f\n", $answer, $ratio;