Implementing Joins using Extensible Pattern Matching

Join patterns are an attractive declarative way to synchronize both threads and asynchronous distributed computations. We explore joins in the context of extensible pattern matching that recently appeared in languages such as F# and Scala. Our implementation supports join patterns with multiple synchronous events, and guards. Furthermore, we integrated joins into an existing actor-based concurrency framework. It enables join patterns to be used in the context of more advanced synchronization modes, such as future-type message sending and token-passing continuations

Combinators for Message-Passing in Haskell

Much code in message-passing programs is tedious, verbose wiring code. This code is error prone and laborious - and tends to be repeated across many programs with only slight variations. By using type-classes, higher-order and monadic functions in Haskell, most of this code can be captured in re-usable high-level combinators that shorten and simplify message-passing programs. We motivate the design and use of these combinators via an example of a concurrent biological simulation, and explain their implementation in the Communicating Haskell Processes library

Distributed Control Flow with Classical Modal Logic

In previous work we presented a foundational calculus for spatially distributed computing based on intuitionistic modal logic. With the modalities # and # we were able to capture two key invariants: the mobility of portable code and the locality of fixed resources. This work investigates issues in distributed control flow through a similar propositions-as-types interpretation of classical modal logic. The resulting programming language is enhanced with the notion of a network-wide continuation, through which we can give computational interpretation of classical theorems (such as #A ##A). Suc

Multicore Scheduling for Lightweight Communicating Processes

Process-oriented programming is a design methodology in which software applications are constructed from communicating concurrent processes. A process-oriented design is typically composed of a large number of small isolated concurrent components. These components allow for the scalable parallel execution of the resulting application on both shared-memory and distributed-memory architectures. In this paper we present a runtime designed to support process-oriented programming by providing lightweight processes and communication primitives. Our run-time scheduler, implemented using lock-free algorithms, automatically executes concurrent components in parallel on multicore systems. Run-time heuristics dynamically group processes into cache-affine work units based on communication patterns. Work units are then distributed via wait-free work-stealing. Initial performance analysis shows that, using the algorithms presented in this paper, process-oriented software can execute with an efficiency approaching that of optimised sequential and coarse-grain threaded designs

A synergy between model-checking and type inference for the verification of value-passing higher-order processes

Abstract. In this paper, we present a formal verification framework for higherorder value-passing process algebra. This framework stems from an established synergy between type inference and model-checking. The language considered here is based on a sugared version of an implicitly typed λ-calculus extended with higher-order synchronous concurrency primitives. First, we endow such a syntax with a semantic theory made of a static semantics together with a dynamic semantics. The static semantics consists of an annotated type system. The dynamic semantics is operational and comes as a two-layered labeled transition system. The dynamic semantics is abstracted into a transitional semantics so as to make finite some infinite-state processes. We describe the syntax and the semantics of a verification logic that allows one to specify properties. The logic is an extension of the modal µ-calculus for handling higher-order processes, value-passing and return of results.

Bigraphical Models of Context-aware Systems

As part of ongoing work on evaluating Milner's bigraphical reactive systems, we investigate bigraphical models of context-aware systems, a facet of ubiquitous computing. We find that naively encoding such systems in bigraphs is somewhat awkward; and we propose a more sophisticated modeling technique, introducing plato-graphical models, alleviating this awkwardness. We argu

C-—: A Portable Assembly Language that Supports Garbage Collection

For a compiler writer, generating good machine code for a variety of platforms is hard work. One might try to reuse a retargetable code generator, but code generators are complex and difficult to use, and they limit one's choice of implementation language. One might try to use C as a portable assembly language, but C limits the compiler writer's flexibility and the performance of the resulting code. The wide use of C, despite these drawbacks, argues for a portable assembly language. C-- is a new language designed expressly for this purpose. The us