Lustre is a
formally defined,
declarative, and
synchronous
Synchronization is the coordination of events to operate a system in unison. For example, the conductor of an orchestra keeps the orchestra synchronized or ''in time''. Systems that operate with all parts in synchrony are said to be synchronou ...
dataflow programming
In computer programming, dataflow programming is a programming paradigm that models a program as a directed graph of the data flowing between operations, thus implementing dataflow principles and architecture. Dataflow programming languages share s ...
language for programming reactive systems. It began as a research project in the early 1980s. A formal presentation of the language can be found in the 1991 Proceedings of the IEEE. In 1993 it progressed to practical, industrial use in a commercial product as the core language of the industrial environment
SCADE, developed by
Esterel Technologies. It is now used for critical control software in
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engine ...
,
helicopters
A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...
, and
nuclear power plants.
Structure of Lustre programs
A Lustre program is a series of ''node'' definitions, written as:
node foo(a : bool) returns (b : bool);
let
b = not a;
tel
Where
foo is the name of the node,
a is the name of the single input of this node and
b is the name of the single output.
In this example the node
foo returns the negation of its input
a, which is the expected result.
Inner variables
Additional internal variables can be declared as follows:
node Nand(X,Y: bool) returns (Z: bool);
var U: bool;
let
U = X and Y;
Z = not U;
tel
Note: The equations order doesn't matter, the order of lines
U = X and Y; and
Z = not U; doesn't change the result.
Special operators
Examples
Edge detection
node Edge (X : bool) returns (E : bool);
let
E = false -> X and not pre X;
tel
See also
*
Esterel
Esterel is a synchronous programming language for the development of complex reactive systems. The imperative programming style of Esterel allows the simple expression of parallelism and preemption. As a consequence, it is well suited for cont ...
*
SIGNAL
In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing' ...
(another dataflow-oriented synchronous language)
*
Synchronous programming language
A synchronous programming language is a computer programming language optimized for programming reactive systems. Computer systems can be sorted in three main classes: (1) transformational systems that take some inputs, process them, deliver their ...
*
Dataflow programming
In computer programming, dataflow programming is a programming paradigm that models a program as a directed graph of the data flowing between operations, thus implementing dataflow principles and architecture. Dataflow programming languages share s ...
References
External links
Synchrone Lab{{Webarchive, url=https://web.archive.org/web/20201125185226/http://www-verimag.imag.fr/Synchrone-main.html?lang=en , date=2020-11-25 Official website
product page
Declarative programming languages
Synchronous programming languages
Hardware description languages
Formal methods
Software modeling language