Typing Context-Dependent Behavioural Variations

Context Oriented Programming (COP) is a hot topic nowadays. A number of programming languages endowed with COP features has been developed. However, some foundational issues remain unclear. This paper proposes adopting static analysis techniques to predict how programs may react in different execution environments. We introduce a core functional language, ContextML, equipped with COP primitives for manipulating contexts and for programming behavioural variations. In particular, we specify the dispatching mechanism, used to select the program fragments to be executed in the current active context. Besides the dynamic semantics we present an annotated type system. It guarantees that the well-typed programs adapt to any context, i.e. the dispatching mechanism always succeeds at runtime.