gistfile1.js

// An object which implements the 
// IAssociative, ILookup, ICloneable protocols:
function MapCursor(data) {
  this.data = mori.is_map(data) ? data : mori.js_to_clj(data)
}
MapCursor.prototype = {
  clone: function() { return new MapCursor(this.data); },
  has: function(key) { return mori.has_key(this.data, key);
  get: function(key, fallback) {
    var val = mori.get(this.data, key, fallback);
    if (mori.is_map(val)) {
      return new MapCursor(val);
    }
    return val;
  },
  set: function(k, v) {
    this.data = mori.assoc(this.data, k, v)
    return this
  },
};

// Define the protocol functions and the associated
// functions in JS
mori.protocol.IAssociative.implement(
  MapCursor.prototype,
  '-contains-key?', 'has',
  '-assoc', 'set'
)
mori.protocol.ICloneable.implement(
  MapCursor.prototype,
  '-clone', 'clone'
)
mori.protocol.ILookup.implement(
  MapCursor.prototype,
  '-lookup', 'get'
)

// Then this should work:
var cursor = new MapCursor({name: {first: 'Tim', last: 'G'}});

mori.get(cursor, 'name');
mori.get_in(cursor, ['name', 'first']);
mori.assoc(cursor, 'key', 'value');