msort.php

<?php

   function p($xs){
      foreach($xs as $x) print("$x ");
      print "\n";
   }

   function split2($xs){
      if(count($xs) == 1) return array($xs, array());

      list($l, $r) = array_chunk($xs, 2);
      return array();
   }

   function msort($xs){
      list($l, $r) = split($xs);
      return merge(
         (count($xs) <= 2) ? array(l, r)
                           : array(msort(l), msort(r)));
   }

   $xs = range(0, 20);
   shuffle($xs);
   p($xs);
   list($x, $y) = array(array(1,2,3), array(6));

   print_r(array_chunk(array(1,2), 2));
   print_r(array_chunk(array(1), 2));
?>