Custom compound types in declarative programs

The present invention extends to methods, systems, and computer program products for creating and manipulating custom compound data types in declarative programs. The present invention allows a developer to create and use custom compound data types without requiring the custom type to be specifically defined (e.g. via registering a custom assembly) in the underlying framework. This is accomplished by providing a data container that is configurable to represent virtually any combination of primitive or compound types defined within the framework. The present invention also provides a declarative model for interacting with data containers representing custom compound data types. This declarative model employs a path-based syntax (or other type of syntax) for accessing the elements of a custom compound data type. Multiple paths can be defined within a single unit of developer input so that multiple elements of a custom data type can be manipulated by the single unit of input.