APLGameOfLife.js

/**
 * This is a copy of https://www.youtube.com/watch?v=a9xAKttWgP4 (Conway's game of life in APL) in 
 * javascript. 
 * 
 * This is a completely functional implementation of game of life,
 * with data being completely immutable.
 * 
 * Author: Uku Tammet
 * Date  : 24.07.2015
 */

function mod(n, m) {
  return ((n % m) + m) % m;
}

function localBinding(v, func) {
  return func(v);
}

function rowRotation(matrix, rotations) {
  return rotations.map(function(rotation) {
    return matrix.map(function(row) {
      return row.map(function(_, index, self) {
        return self[mod(index+rotation, self.length)];
      });
    });
  });
}

function columnRotation(matrix, rotations) {
  return rotations.map(function(rotation) {
    return matrix.map(function(row, index, self) {
      return self[mod(index + rotation, self.length)]
    });
  });
}

function matrixSum(prev, crnt) {
  return prev.map(function(row, x) {
    return row.map(function(column, y) {
      return column + crnt[x][y];
    });
  });
}

/**
 * Life takes in the previous generation and returns the next generation.
 */
function life (previousGeneration) {
  return localBinding([1, 0, -1], function(rotations) {
    return rowRotation(previousGeneration, rotations).map(function(matrix) {
      return columnRotation(matrix, rotations).reduce(matrixSum);
    }).reduce(matrixSum);
  }).map(function(row, x) {
    return row.map(function(column, y) {
      return column === 3 || (column === 4 && previousGeneration[x][y] === 1) ? 1 : 0;
    });
  });
}

// End of implementation, test the function here.

function printMatrix(matrix) {
  matrix.forEach(function(row) {
    console.log(row.reduce(function(prev, crnt) {
      return prev + ' ' + crnt;
    }));
  });
}

var original = [
  [0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0],
  [0, 0, 1, 1, 0],
  [0, 1, 1, 0, 0],
  [0, 0, 1, 0, 0],
  [0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0]
];

printMatrix(original);
printMatrix(life(original));