Immutable type checking for Simon

gistfile1.cs

class Mutable {
}

[Immutable]
public class ImmutableB
{
   public readonly A = new ImmutableA();
}

[Immutable]
public class ImmutableA
{
   public readonly M = new Mutable(); // here should the build stop and tell you that you can not use mutable types inside of immutable types.
}

// Immutable are all types with Immutable attribute + a whitelist of framework types or types from other assemblies.

The detection also need to go far beyond. Like:

• No public fields
• No setts
• No method should change the internal state after construction