Dependent Types for Multi-Rate Flows in Synchronous Programming

Synchronous programming languages emerged in the 1980s as t ools for implementing reactive systems, which interact with events from physical environment s and often must do so under strict timing constraints. In this report, we encode inside ATS various re al-time primitives in an experimental synchronous language called Prelude, where ATS is a statically typed language with an ML-like functional core that supports both dependent types (of DML-styl e) and linear types. We show that the verification requirements imposed on these primitives can b e formally expressed in terms of dependent types in ATS. Moreover, we modify the Prelude compiler t o automatically generate ATS code from Prelude source. This modified compiler allows us to sole ly r ly on typechecking in ATS to discharge proof obligations originating from the need to ty pecheck Prelude code. Whereas ATS is typically used as a general purpose programming language, w e hereby demonstrate that it can also be conveniently used to support some forms of advanced stati c checking in languages equipped with less expressive types.