Unless I'm missing something, DataList & DataToken implementation does not support implicit casts. It does not support the use of .Cast<T> calls either. Let's say you have a DataList full of string tokens: DataList a = new DataList() { "First", "Second", "Third" }; What's normally the shortest way to concatenate it into "First, Second, Third"? Something like this: String.Join(", ", a.Cast<string>().ToArray()); But we can't do that, since there is no exposed definition of .Cast<T> for DataList or DataToken ( DataList.ToArray().Cast<string>().ToArray() ). Well, Array.ConvertAll() is exposed, but you don't support lambdas. This is better, but now an effective one-liner is split into multiple segments all over the code. So the only valid way to do that Join is to manually iterate: string[] items = new string[a.DataList.Count]; for (int i = 0; i < items.Length; i++) { items[i] = a.ToArray()[i].ToString(); } string output = String.Join(", ", items); Pretty much the only unsafe cast sources are of types DataDictionary , DataList , Reference , and Error (kind of). You already return type name in those cases, so just support cast operators and implicit casting.
