The subject disclosure pertains to layering of a plurality of type systems. A development environment and language compilers can support multiple data models and their type systems in the same program. Elements of a program such as expressions can then be associated with several types from the multiple type systems. Compilers can employ the information provided by additional type systems to improve static type checking. Furthermore, the information can be bubbled up to a user in a plurality of forms including but not limited to intelligent assistance, auto-completion, tool tips, error information, and return types to enhance the program development experience.