See my other comment; it does make sense to have a list of objects which share some interface. In the case you suggest, it is a very trivial and not-very-usefu

See my other comment; it does make sense to have a list of objects which share some interface. In the case you suggest, it is a very trivial and not-very-useful interface, but an interface nonetheless. You can do this with objects even in strictly-typed languages like OCaml or Mercury; code which iterates over the list is simply restricted to use only those methods which all elements have in common. Of course in languages which don't support a universal "object" type (say OCaml or C) you cannot do this -- numbers and strings have no interface in common. Those languages take advantage of this by not storing type information in collections (e.g. OCaml's float arrays, or any array in C), thus resulting in more compact memory footprints. If they instead allowed heterogeneous collections, the memory footprint of such collections would double.