A Programming Language

APL is at the same time a mathematical notation and a complete, high level language for programming computers.

APL makes it easier for many Domain or Subject Matter Experts to write (components of) applications, because it is a notation which is more closely related to already familiar notations, than are traditional programming languages.

APL is a dynamic, functional language based on an inherently parallel, array-oriented notation, where primitive functions typicially apply to all items of argument. For example, the result of the expression (100 200 300 × 1 1.5 2) is (100 300 600).

APL is concise, using symbols to denote all its primitive functions and operators, to avoid having reserved words which might conflict with the names used for the domain-specific functions that APL users typically develop as extensions to APL.

A function to compute the average of a list can be defined as avg←{(+⌿⍵)÷≢⍵}: It divides the sum of the items in the right argument (+⌿⍵) by the number of items (≢⍵).

Enter APL expressions in the box on the right, and view the results! For an introduction and examples of expressions to try out, take a look at Mastering Dyalog APL!