Simple function for declaring modules.

module.js

function module(scope, fn) {
  var result = fn();
  if (_.isEmpty(result)) {
    throw "When defining a module, you _must_ return an object containing exports.";
  }

  var split = scope.split('.');
  if (split.length > 1) {
    var parts = _.initial(split, 1),
        last = _.last(split),
        target = window;

    for (var i = parts.length - 1; i >= 0; i--) {
      var part = parts[i];

      if (_.isUndefined(target[part])) {
        target[part] = {};
      }
      else if (!_.isObject(target[part])) {
        throw "You can't define a module against a scope that's not an object.";
      }

      target = target[part];
    };

    target[last] = result;
  }
  else {
    window[split[0]] = result;
  }

  return result;
};