Lustre

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.