Spike for functionally solving MineSweeper Kata

minesweeper_functional_kata.php

<?php

$grid = array(
  array('*', '*', '*', '*', '*'),
  array('*', '.', '*', '.', '*'),
  array('*', '*', '.', '.', '*'),
  array('*', '*', '.', '*', '*'),
  array('*', '*', '*', '*', '*')
);

$neighbourCoords = array(
  array(-1, -1),
  array(0, -1),
  array(1, -1),
  array(-1, 0),
  array(1, 0),
  array(-1, 1),
  array(0, 1),
  array(1, 1)
);

$findNeighbours = function($grid, $x, $y) use ($neighbourCoords) {
  $neighbours = array();
  foreach ($neighbourCoords as $increment) {
    $targetY = $y + $increment[1];
    $targetX = $x + $increment[0];
    $neighbours[] = $grid[$targetY][$targetX];
  }
  return $neighbours;
};

$findMines = function($sum, $cell) {
  return $sum += ('*' == $cell) ? 1 : 0;
};

for ($y = 0; $y < 5; $y++) {
  for ($x = 0; $x < 5; $x++) {
    $neighbours = $findNeighbours($grid, $x, $y);
    $mines = array_reduce($neighbours, $findMines, 0);
    echo "Mines at $x,$y: $mines\n";
  }
}