Semantics of an Exception Mechanism for Bulk Synchronous Parallel ML

Bulk Synchronous Parallel ML is a high-level language for programming parallel algorithms. Built upon OCaml and using the BSP model, it provides a safe setting for their implementation, avoiding concurrency related problems (deadlocks, indeterminism). Only a limited set of the features of OCaml can be used in BSML to respect its properties of safety: this paper describes a way to add exception handling to this set by extending and adapting OCaml 's exceptions. After a precise definition of the problems that arise and an informal description of the solutions, an extension of BSML is proposed. Formal semantics define the behaviour in all possible cases, followed by a short description of the implementation.