> We've extended all objects including numbers to respond to the bar function.We can provide more specific implementations at anytime, i.e. by using extend-type on string, array, Vector, even your custom types

Mimicking that in javascript:

    Object.defineProperty Object.prototype, 'bar',
        value: -> 'whatever'
        
    'foo'.bar()
    (1).bar()
    [1,2,3].bar()

More specific implementations can be defined on the other prototypes. This is totally safe (except for oldIE).

Making objects behave as functions (actually the opposite) is also possible:

    MagicHash = (props) ->
      f = (key) -> f[key]
      f[k] = v for k,v of props
      return f
  
    address = new MagicHash
      street: '1010 Foo Ave.'
      apt: '1111'
      city: 'Bit City'
      zip: '000000000'

    address.apt
    #> '1111'
    ['street', 'zip'].map address
    #> [ '1010 Foo Ave.', '000000000' ]

or

    map = (fn, arr) -> arr.map fn

    map address, ['street', 'zip']
    #> [ '1010 Foo Ave.', '000000000' ]
    

And no, I have no idea how this could be useful...