The programming language APL is distinctive in being symbolic rather than lexical: its primitives are denoted by symbols, not words. These symbols were originally devised as a mathematical notation to describe algorithms. APL programmers often assign informal names when discussing functions and operators (for example, product for ×/) but the core functions and operators provided by the language are denoted by non-textual symbols.
== Monadic and dyadic functions ==
Most symbols denote functions or operators. A monadic function takes as its argument the result of evaluating everything to its right...