This paper describes the language Lustre, which is a dataflow synchronous language, designed for programming reactive systems --- such as automatic control and monitoring systems --- as well as for describing hardware. The dataflow aspect of Lustre makes it very close to usual description tools in these domains (block-diagrams, networks of operators, dynamical samples-systems, etc: : : ), and its synchronous interpretation makes it well suited for handling time in programs. Moreover, this synchronous interpretation allows it to be compiled into an efficient sequential program. Finally, the Lustre formalism is very similar to temporal logics. This allows the language to be used for both writing programs and expressing program properties, which results in an original program verification methodology. 1 Introduction Reactive systems Reactive systems have been defined as computing systems which continuously interact with a given physical environment, when this environment is unable to sy...

The Alpha language results from research on automatic synthesis of systolic algorithms. It is based on the recurrence equation formalism introduced by Karp, Miller and Winograd in 1967. The basic objects of Alpha are variables indexed on integral points of a convex set. It is a functional/equational language, whose definition is particularly well-suited to expressing regular algorithms, as well as transformations of these algorithms from their initial mathematical specification to an implementation on a synchronous parallel architecture. In particular, Alpha makes it easy to define, prove and implement basic transformations such as Leiserson and Saxe's retiming, space-time reindexing, localization, and partitioning. We describe Alpha, its use for expressing and derivating systolic arrays, and the development environment Alpha du Centaur for this language. This work is funded by the French Coordinated Research Program C 3 and by the ESPRIT BRA project NANA. 1 1. INTRODUCT...

This document is an introduction to the language Lustre V4 and its associated tools. We will not give a systematic presentation of the language, but a complete bibliography is added. The basic references are [8, 12]. The most recent features (arrays, recursive nodes) are described in [32]