Abstract: Anonymous types for a programming language. Non-denotable anonymous types are types that a compiler generates on behalf of a programmer and can then be used as nominal types. Insofar as anonymous types do not have a name, they can be used only inside a method in which they are created. Additionally, an anonymous type cannot be exposed in any way outside of the method. Syntax to create an anonymous type is useful when employed with a Select operator to generate a result with a particular shape, without the need of having a regular type for it. Anonymous types are expressible such that an expression of that type can be written. Translation of an anonymous type by a compiler generates a nominal class that implements Equals and GetHashCode methods. There is equivalence of anonymous types within the same method, and conversion of an unrealized structural type into structurally compatible nominal type.