Union and intersection types to support both dynamic and static typing

Although static typing provides undeniable benefits for the development of applications, dynamically typed languages have become increasingly popular for specific scenarios. Since each approach offers different benefits, the StaDyn programming language has been designed to support both dynamic and static typing. This paper describes the minimal core of the StaDyn programming language. Its type system performs type reconstruction over both dynamic and static implicitly typed references. A new interpretation of union and intersection types allows statically gathering the type information of dynamic references, which improves runtime performance and robustness. The evaluation of the generated code has shown how our approach offers an important runtime performance benefit.

Research highlights
► StaDyn is a new programming language that supports both dynamic and static typing.
► A novel subtyping relation for dynamic union and intersection types is defined.
► Static type information is inferred, even over dynamic references.
► Many type errors are detected by the compiler when using dynamic references.
► The .Net generated code involves a runtime performance improvement over C# and VB.