Why can't an anonymous class have a lambda property, but it can have a Func<> property? [duplicate]

Question

I'm trying to learn C#'s restrictions on an anonymous type. Consider the following code:

  var myAwesomeObject = new {
      fn1 = new Func<int>(() => { return 5; }),
      fn2 = () => { return 5; } 
  };

So we've got two properties that are actually functions:

• fn1: A Func<int> that returns 5.
• fn2: A lambda function that returns 5.

The C# compiler is happy to work with fn1, but complains about fn2 :

cannot assign lambda expression to anonymous type property.

Can someone explain why one is ok but the other is not?

Answer 1

Because there is no way for the compiler to know the type of () => { return 5; }; it could be a Func<int>, but it could also be any other delegate with the same signature (it could also be an expression tree). That's why you have to specify the type explicitly.