TommyCarlier said: public interface IReadOnlyCollection<T>  :
IEnumerable<T>     int Count { get; } If it supports count would
it not also support indexed based access? and I agree..
personally readonlycollection makes me cringe.. I don't like
exposing it, and it can only ever then act as runtime
protection.. I would love some readonly interfaces for data
structures.. and perhaps even some immutable data structure
interfaces and implementations (surely the implementations
already exist in f# for example).