Imperative Languages
Languages centered on sequences of statements that change program state. The oldest paradigm, rooted in the von Neumann architecture of fetch-decode-execute cycles.
Sub-topics
Created at IBM by John Backus in 1957. The first widely used high-level programming language, designed for scientific and engineering computation. Still dominant in HPC, weather modeling, and numerical simulation.
Algorithmic Language, first specified in 1958 (ALGOL 58) and refined as ALGOL 60. Introduced block structure, lexical scoping, and BNF notation. Never widely used commercially but profoundly influenced nearly every subsequent language.
Common Business-Oriented Language, created in 1959 by a committee led by Grace Hopper. Designed for business data processing with English-like syntax. Still runs an estimated 95% of ATM transactions and 80% of in-person transactions worldwide.
Beginner's All-purpose Symbolic Instruction Code, created by John Kemeny and Thomas Kurtz at Dartmouth in 1964. Designed to make computing accessible to non-science students. Microsoft's first product was a BASIC interpreter (1975).
Created by Niklaus Wirth in 1970 as a small, efficient language for teaching structured programming. Influenced Ada, Modula-2, Oberon, and Delphi. Borland's Turbo Pascal (1983) made it commercially successful.
Designed 1977-1983 for the US Department of Defense by Jean Ichbiah's team. Named after Ada Lovelace. A strongly typed, modular language with built-in concurrency, used in aviation, defense, and safety-critical systems.
Created at CWI Amsterdam in the early 1980s by Leo Geurts, Lambert Meertens, and Steven Pemberton. An educational language emphasizing simplicity and readability. Guido van Rossum worked on ABC before creating Python, which it directly inspired.
Modula-2 (1978) and Modula-3 (1988), both by Niklaus Wirth and successors. Evolved Pascal with modules, coroutines, and systems programming features. Modula-3 influenced Python's module system and Java's design.
Created by Charles Moore around 1970. A stack-based, extensible language with an interactive development style. Extremely minimalist — the programmer builds the language up from primitives. Used in embedded systems and Open Firmware.
Released by Borland in 1995. Object Pascal with a visual RAD IDE that dominated Windows desktop development in the late 1990s. Anders Hejlsberg designed Turbo Pascal and early Delphi before moving to Microsoft to create C#.