How to validate fields in array type subfields?

[mocheng]

For example, there is params defined as below

var params = {
    users: [
         {
              name: 'mike',
              gender: 'M'
         },
         {
              name: 'tom',
              gender: 'M'
         }
    ]
};

Currently, there is no way to validate the first user's name like
validr.validate('users[0].name', 'first user should have name').isLength(1).

How to extend current method to support this?