Icon
Icon is a high-level, general-purpose programming language introduced in the 1970s by Ralph Griswold. It features a unique goal-directed evaluation model and powerful string- and list-processing capabilities, notably using success and failure rather than Boolean logic for control flow. The language influenced later scripting languages like Python and JavaScript.
Background
Icon is a high-level, imperative programming language created in the late 1970s by Ralph Griswold at the University of Arizona. It is best known for its novel "goal-directed evaluation" and powerful string- and list-processing features. Unlike most languages of its era (and today), Icon lets expressions succeed or fail rather than just return true/false, enabling very concise pattern matching and search logic without explicit loops. While never a mainstream commercial language, Icon was influential in the design of later languages (e.g., Python's generators, Lua, and the concept of generators in general). Its successor, Unicon, extends Icon with object-oriented and other modern features.