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.