If List<> inherits IList<>, and MyIdentity inherits IIdentity, then why the heck the C# compiler cannot cast from List<MyIdentity> to IList<IIdentity>?????? It is the same, the compiler is not smart enough to know this. So to satisfy the compiler - acting as a good compiler slave - I have to write this

IList<IIdentity> returnList = new List<IIdentity>();
// A variable name cannot be stupider
foreach (var item in originalList)
return returnList;

And people were wondering why dynamic languages takes less lines of code.