Practical Parameterised Session Types

Parameterised session types is a type theory studied in the context of multiparty session types, that addresses statically the problem of type-safe, deadlock-free interactions in programs of an arbitrary number of processes. The previous work supporting parameterised session types has several shortfalls that limit their utility in practice. We eliminate the shortfalls by introducing a programming idiom of roles and a new type system. Roles have the same design as classes in languages such as Java and C#, while the previous model presents an amorphous syntax without concepts on how to incorporate parameterised session types into a mainstream language. The previous model requires programmers to write processes types, in addition to global types, for type-checking, while this model preserves multiparty’s lightweight type annotations and type-checking strategy of simply global types. The previous model requires values of parameters to range over finite sets of natural numbers, while this model allows infinite sets of them.