A rough implementation of https://en.wikipedia.org/wiki/Weasel_program, experimenting with a simple genetic algorithm.

methinks.php

<?php

/**
 * Genetic algorithm test.
 * This is basically a rough implementation of the Weasel program
 * https://en.wikipedia.org/wiki/Weasel_program
 */

$ascii = "abcdefghijklmnopqrstuvwxyz "; // Ascii characters

$string_match = "dance then wherever you may be i am the lord of the dance said he"; // String we're looking for

$string_match = strtolower($string_match);


/** Generate a random string */
function random_string($length) {
	global $ascii;
	
	$s = "";
	
	
	for ($n=0; $n < $length; $n++)
		$s.= strtolower($ascii[rand(0,26)]);
		
	return $s;
}

/** Mutate a given string */
function random_string_from_src($string) {
	
	global $ascii;
	
	for ($n=0; $n<strlen($string); $n++) {
			if (rand(0,19)==0) $string[$n] = $ascii[rand(0, 26)];
			
				
	}
	
	return $string;
}

/** Score a string against it's target */
function get_score($string, $target) {
	$score = 0;
	for ($n =0; $n < strlen($string); $n++)
		if ($string[$n] == $target[$n]) $score ++;
		
	return $score;
}

/** Mutate a string, produce children and pick the best one */
function BREED($string) {
	global $string_match;
	$best = $string;
	$best_score = get_score($string, $string_match);
	
	for ($n = 0; $n < 100; $n++)
	{
		$v = random_string_from_src($string);
		if (get_score($v, $string_match)>=$best_score) {
			$best = $v;
			$best_score = get_score($v, $string_match);
		}
	}
	
	return $best;
}

$cnt = 0;
$v = random_string(strlen($string_match));
do {
	$v = BREED($v);
	$score = get_score($v, $string_match);
	echo "Generation $cnt: $v ($score) \n";
	
	$cnt ++;
} while($score < strlen($string_match));