Konrad Zuse´s Plankalkül: the first high-level, “non von Neumann” programming language

Konrad Zuse was the first person in history to build a working digital computer, a fact that is still not generally acknowledged. Even less known is that in the years 1943-1945, Zuse developed a high-level programming model and, based on it, an algorithmic programming language called Plankalkül (Plan Calculus). The Plankalkül features binary data structure types, thus supporting a loop-free programming style for logical or relational problems. As a language for numerical applications, Plankalkül already had the essential features of a “von Neumann language”, though at the level of an operator language. Consequently, the Plankalkül is in some aspects equivalent and in others more powerful than the von Neumann programming model that came to dominate programming for a long time. To find language concepts similar to those of the Plankalkül, one has to look at “non-von Neumann languages” such as APL or the relational algebra. This paper conveys the syntactic and semantic flavor of the Plankalkül, without presenting all its syntactic idiosyncrasies. Rather, it points out that the Plankalkül was not only the first high-level programming language but in some aspects conceptually ahead of the high-level languages that evolved a decade later