. This paper presents a new dialect of Scheme aimed towards concurrency and distribution. It offers a few primitives, including first-class continuations, with very simple semantics. Numerous examples are given showing how to program the classical concurrent control operators such as future, pcall and either. The implementation is sketched and presented along the lines of a metacircular interpreter. This paper presents the idiom of Icsla 1 , a language belonging to the Lisp family and more precisely a descendant of Scheme. This dialect has been designed with respect to the following main objectives: -- It should have a very simple and understandable semantics, with few but powerful and unrestrictively combinable concepts; -- It should offer concurrency, distribution and some other modern features such as sophisticated control features while not sacrificing the variety of styles traditionally offered by Lisp. These goals are rather general and deserve further comment. Following Sche...

Today's message passing architectures are characterized by high communication costs and they typically lack hardware support for synchronization and scheduling. These deficiencies present a severe obstacle to obtaining efficient implementations of parallel applications whose communication patterns are either highly irregular or dependent on dynamic information. In this paper we present a model based on continuation-passing threads in which we try to overcome these difficulties. The model incorporates two effective software mechanisms targeted towards lengthening sequential threads in order to offset the costs of dynamic scheduling, and towards preserving the locality of computations to reduce the network traffic. The model is currently implemented as a C language extension along with a runtime system implemented on the CM-5 that embodies a work stealing scheduler. Real world applications written in this package, such as ray-tracing and protein folding, have shown impressive speedup res...

The Lisp family of languages has traditionally been a privileged domain where linguistic experiments were done, this paper presents a new dialect offering concurrency and distribution. This dialect, nicknamed CD-Scheme, has been designed above Scheme with as few as possible features to allow a great expressiveness but still to retain the original consistency and simplicity of Scheme. We explicitly show how common parallel constructs can be written in regular CD-Scheme. A denotational semantics is also presented that expresses the detailed meaning of assignment, data mutation, continuations in presence of concurrency and distribution. This semantics offers a basis to understand new proposals of concurrent or distributed features and may be used to justify compiler optimizations or implementation techniques. The proposed set of features of CD-Scheme can be also used to extend languages other than Scheme. CD-Scheme is a concurrent, distributed and conservative extension of Scheme, a dial...

A substantial amount of work has been devoted to the proof of correctness of various program analyses but much less attention has been paid to the correctness of compiler optimisations based on these analyses. In this paper we tackle the problem in the context of strictness analysis for lazy functional languages. We show that compiler optimisations based on strictness analysis can be expressed formally in the functional framework using continuations. This formal presentation has two benefits: it allows us to give a rigorous correctness proof of the optimised compiler; and it exposes the various optimisations made possible by a strictness analysis. 1 Introduction Realistic compilers for imperative or functional languages include a number of optimisations based on non-trivial global analyses. Proving the correctness of such optimising compilers can be done in three steps: 1. proving the correctness of the original (unoptimised) compiler; Correspondence regarding this paper should be ...