Conways Game of Life in CoffeeScript

game_of_life.coffee

# Utility methods

flatten_nested_array = (array) ->
  [].concat array...

includes = (item, coll) ->  
  item = key_to_array(item)
  for potential_match in coll
    return true if item[0] == potential_match[0] && item[1] == potential_match[1]
  false

key_to_array = (string) ->
  return string if typeof string != 'string'
  splitted = string.split(',')
  [parseInt(splitted[0]), parseInt(splitted[1])]

# Main

# world is a set of live cells
# map all the neighbours of live cells in the world
# reduce to the frequencies of the neighbours occuring i.e. [1, 1] occurs 4 times 
# reduce with conway rules: (2 & 3 and alive survives) or (3 and dead becomes alive)

neighbours_of = (x, y) ->
  [[x-1, y+1], [x, y+1], [x+1, y+1],
   [x-1, y  ],           [x+1, y  ],
   [x-1, y-1], [x, y-1], [x+1, y-1]]

frequencies = (all_neighbouring_cells) ->
  frequencies_found = {}
  for candidate_cell in all_neighbouring_cells
    frequencies_found[candidate_cell] ||= 0
    frequencies_found[candidate_cell]++
  frequencies_found
  
neighbour_frequencies = (world) ->
  neighbours = (neighbours_of(cell[0], cell[1]) for cell in world)
  neighbours = flatten_nested_array(neighbours)
  frequencies(neighbours)

survives = (num_of_neighbours, is_alive) ->
  return true if is_alive and (num_of_neighbours == 2 or num_of_neighbours == 3)
  return true if !is_alive and num_of_neighbours == 3 
  false

evolve = (world) ->
  nf = neighbour_frequencies(world)
  survivors = key_to_array(cell) for cell, count of nf when survives(count, includes(cell, world))

game_loop = (world, times_to_evolve, listener) ->
  evolved = 0
  interval = null
  iteration = ->
    listener(world)
    world = evolve(world)
    evolved++
    clearInterval interval if times_to_evolve && evolved>times_to_evolve
  
  interval = setInterval iteration, 400


class Grid
  constructor: (x,y) ->
    @svg = d3.select('body').append('svg')
                .attr('width', 5*x)
                .attr('height', 5*y)

  
  render: (data) =>
    rects = @svg.selectAll('rect')
              .data(data, (d) -> "#{d[0]},#{d[1]}")

    rects.enter().append('rect')
        .attr('width', 0)
        .attr('height', 0)
        .attr('x', (d)->2.5+d[0]*5)
        .attr('y', (d)->2.5+d[1]*5)
      .transition().duration(400)
        .attr('width', 5)
        .attr('height', 5)
        .attr('x', (d)->d[0]*5)
        .attr('y', (d)->d[1]*5)
      
    rects.exit().remove()

appendScript = (src, cb) ->
  script = document.createElement('script')
  script.type = 'text/javascript'
  script.async = true
  script.onload = cb
  script.src = src
  document.getElementsByTagName('head')[0].appendChild(script)

appendScript 'http://code.jquery.com/jquery-1.8.2.min.js', ->
  appendScript 'http://cdnjs.cloudflare.com/ajax/libs/d3/2.10.0/d3.v2.min.js', ->

    $ ->
      world = [[0, 1], [1, 1], [2, 1], [2,2], [3,3], [3,2]]
      g = new Grid(40,40)
      game_loop(world, 5, g.render)

# prints
# ["0,1", "1,1", "2,1"]
# ["1,2", "1,1", "1,0"]
# ["0,1", "1,1", "2,1"]
# ["1,2", "1,1", "1,0"]
# ["0,1", "1,1", "2,1"]

gol.js

// Generated by CoffeeScript 1.3.3
(function() {
  var Grid, appendScript, change_listener, evolve, flatten_nested_array, frequencies, game_loop, includes, key_to_array, neighbour_frequencies, neighbours_of, survives,
    __bind = function(fn, me){ return function(){ return fn.apply(me, arguments); }; };

  flatten_nested_array = function(array) {
    var _ref;
    return (_ref = []).concat.apply(_ref, array);
  };

  includes = function(item, coll) {
    var potential_match, _i, _len;
    item = key_to_array(item);
    for (_i = 0, _len = coll.length; _i < _len; _i++) {
      potential_match = coll[_i];
      if (item[0] === potential_match[0] && item[1] === potential_match[1]) {
        return true;
      }
    }
    return false;
  };

  key_to_array = function(string) {
    var splitted;
    if (typeof string !== 'string') {
      return string;
    }
    splitted = string.split(',');
    return [parseInt(splitted[0]), parseInt(splitted[1])];
  };

  neighbours_of = function(x, y) {
    return [[x - 1, y + 1], [x, y + 1], [x + 1, y + 1], [x - 1, y], [x + 1, y], [x - 1, y - 1], [x, y - 1], [x + 1, y - 1]];
  };

  frequencies = function(all_neighbouring_cells) {
    var candidate_cell, frequencies_found, _i, _len;
    frequencies_found = {};
    for (_i = 0, _len = all_neighbouring_cells.length; _i < _len; _i++) {
      candidate_cell = all_neighbouring_cells[_i];
      frequencies_found[candidate_cell] || (frequencies_found[candidate_cell] = 0);
      frequencies_found[candidate_cell]++;
    }
    return frequencies_found;
  };

  neighbour_frequencies = function(world) {
    var cell, neighbours;
    neighbours = (function() {
      var _i, _len, _results;
      _results = [];
      for (_i = 0, _len = world.length; _i < _len; _i++) {
        cell = world[_i];
        _results.push(neighbours_of(cell[0], cell[1]));
      }
      return _results;
    })();
    neighbours = flatten_nested_array(neighbours);
    return frequencies(neighbours);
  };

  survives = function(num_of_neighbours, is_alive) {
    if (is_alive && (num_of_neighbours === 2 || num_of_neighbours === 3)) {
      return true;
    }
    if (!is_alive && num_of_neighbours === 3) {
      return true;
    }
    return false;
  };

  evolve = function(world) {
    var cell, count, nf, survivors, _results;
    nf = neighbour_frequencies(world);
    _results = [];
    for (cell in nf) {
      count = nf[cell];
      if (survives(count, includes(cell, world))) {
        _results.push(survivors = key_to_array(cell));
      }
    }
    return _results;
  };

  game_loop = function(world, times_to_evolve, listener) {
    var evolved, interval, iteration, _i, _results;
    evolved = 0;
    interval = null;
    iteration = function() {
      listener(world);
      world = evolve(world);
      evolved++;
      if (times_to_evolve && evolved > times_to_evolve) {
        return clearInterval(interval);
      }
    };
    interval = setInterval(iteration, 400);
    _results = [];
    for (_i = 1; 1 <= times_to_evolve ? _i <= times_to_evolve : _i >= times_to_evolve; 1 <= times_to_evolve ? _i++ : _i--) {
      listener(world);
      _results.push(world = evolve(world));
    }
    return _results;
  };

  change_listener = function(new_world) {
    var cell;
    return console.log((function() {
      var _i, _len, _results;
      _results = [];
      for (_i = 0, _len = new_world.length; _i < _len; _i++) {
        cell = new_world[_i];
        _results.push(cell.toString());
      }
      return _results;
    })());
  };

  Grid = (function() {

    function Grid(x, y) {
      this.render = __bind(this.render, this);
      this.svg = d3.select('body').append('svg').attr('width', 5 * x).attr('height', 5 * y);
    }

    Grid.prototype.render = function(data) {
      var rects;
      rects = this.svg.selectAll('rect').data(data, function(d) {
        return "" + d[0] + "," + d[1];
      });
      rects.enter().append('rect').attr('width', 0).attr('height', 0).attr('x', function(d) {
        return 2.5 + d[0] * 5;
      }).attr('y', function(d) {
        return 2.5 + d[1] * 5;
      }).transition().duration(400).attr('width', 5).attr('height', 5).attr('x', function(d) {
        return d[0] * 5;
      }).attr('y', function(d) {
        return d[1] * 5;
      });
      return rects.exit().remove();
    };

    return Grid;

  })();

  appendScript = function(src, cb) {
    var script;
    script = document.createElement('script');
    script.type = 'text/javascript';
    script.async = true;
    script.onload = cb;
    script.src = src;
    return document.getElementsByTagName('head')[0].appendChild(script);
  };

  appendScript('http://code.jquery.com/jquery-1.8.2.min.js', function() {
    return appendScript('http://cdnjs.cloudflare.com/ajax/libs/d3/2.10.0/d3.v2.min.js', function() {
      return $(function() {
        var g, world;
        world = [[0, 1], [1, 1], [2, 1], [2, 2], [3, 3], [3, 2]];
        g = new Grid(40, 40);
        return game_loop(world, 5, g.render);
      });
    });
  });

}).call(this);

index.html

<script src='https://raw.github.com/gist/3970282/23e9325966140a6923e3e0e409079996b342b3ee/gol.js'></script>