Limitations of the dynamic type in C#

Question

Could you give me some reasons for limitations of the dynamic type in C#? I read about them in \"Pro C# 2010 and the .NET 4 platform\". Here is an excerpt (if quoting books

Answer 1

Lambdas: I think that one reason for not supporting lambdas as parameters to dynamic objects is that the compiler wouldn't know whether to compile the lambda as a delegate or as an expression tree.

When you use a lambda, the compiler decides based on the type of the target parameter or variable. When it is Func<...> (or other delegate) it compiles the lambda as an executable delegate. When the target is Expression<...> it compiles lambda into an expression tree.

Now, when you have a dynamic type, you don't know whether the parameter is delegate or expression, so the compiler cannot decide what to do!

Extension methods: I think that the reason here is that finding extension methods at runtime would be quite difficult (and perhaps also inefficient). First of all, the runtime would need to know what namespaces were referenced using using. Then it would need to search all classes in all loaded assemblies, filter those that are accessible (by namespace) and then search those for extension methods...