A Programming Language (APL)

APL is commonly used in a diverse set of problem domains, such as mathematics, scientific research, visualization, engineering, robotics and actuarial science. The language is written with the unique and non-standard APL character set. Iverson claimed that using this set produces a notation ability that surpasses a regular character set. Accordingly, APL’s power relies on the denotation of common array operators, functions and their combinations by a single dedicated symbol (primitive). The result is a language that is not easy to read. However, APL has a small yet ardent user base in finance, insurance and mathematical applications.

APL programs are more likely to be interpreted in the APL workspace rather than compiled. Unlike other languages evaluated from top to bottom, APL expressions are evaluated from right to left. Originally, APL did not contain control structures. However, modern implementations generally include a comprehensive set of control structures that allow for data separation and program flow control.

APL has been standardized by the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO).

APL programs are best written by using a special keyboard with APL-specific symbolic notation or remapping a general keyboard and using APL language decals to indicate APL functions.