Lucid (programming language)

Lucid is a dataflow programming language designed by Edward A. Ashcroft and William W. Wadge to experiment with programming models outside the conventional step-by-step von Neumann style, first appearing in 1976 and later described fully in their 1985 book Lucid, the Dataflow Programming Language. Rather than a sequence of instructions that change variables over time, a Lucid program defines each variable as an entire stream of values across a notional dimension such as time, and expressions describe how those streams relate to one another, so the language's evaluation model follows data as it flows between definitions rather than following a fixed order of statements. Lucid is typeless. Its first working interpreter, pLucid, and later systems such as GIPSY, along with a range of documented dialects, extended the original design and let Lucid's dataflow ideas be tested in practice.