S-Net: A Typed Stream Processing Language

We propose a view on a data-processing application as a typed streaming network. The arcs of the network represent recordvalued data streams and the nodes encapsulate recurrence relations on them. We propose a type system in which both the arcs and the nodes are statically subtyped, with the overall subtyping consistency of the network assured by type reconciliation algorithms. The proposed type system makes extensive use of a homomorphically-restricted subtyping, which, on the one hand, provides for generic node specification and, on the other, supports efficient type inference and type reconciliation.