computer science

Lustre (programming language)

Lustre (programming language) is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lustre (programming language) rather than just read about it. In short: Lustre is a formally defined, declarative, and synchronous dataflow programming language for programming reactive systems. It began as a research project in the early 1980s.

Key takeaways

Lustre (programming language) belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Lustre (programming language) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Lustre (programming language) from memory before moving on to harder problems.

Reference excerpt

Lustre is a formally defined, declarative, and synchronous dataflow programming 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, helicopters, and nuclear power plants.

Structure of Lustre programs A Lustre program is a series of node definitions, written as:

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:

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

Rising Edge detection

Falling Edge detection

See also Esterel SIGNAL (another dataflow-oriented synchronous language)

References

External links Synchrone Lab Archived 2020-11-25 at the Wayback Machine Official website SCADE product page

Worked examples

Example 1 — a first encounter with Lustre (programming language)

Start with the simplest possible case. Write down what Lustre (programming language) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lustre (programming language) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lustre (programming language) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lustre (programming language)

In research: Lustre (programming language) appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Lustre (programming language) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Lustre (programming language) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Declarative programming languages, Formal methods, Hardware description languages, so understanding it makes those chapters shorter.
In everyday life: Look for Lustre (programming language) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Lustre (programming language) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lustre (programming language) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Lustre (programming language) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lustre (programming language) in simple terms?

Lustre is a formally defined, declarative, and synchronous dataflow programming language for programming reactive systems. It began as a research project in the early 1980s.

Why does Lustre (programming language) matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lustre (programming language)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lustre (programming language).