an ancient programming language adapted to a JavaScript-dominated world
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An APL interpreter written in JavaScript. Runs in a browser or NodeJS.

Supports: most primitives, dfns ({⍺ ⍵}), nested arrays, complex numbers (1j2), infinities (¯ or ), forks and atops, strand assignment ((a b)←c), indexed assignment (a[b]←c), user-defined operators ({⍺⍺ ⍵⍵}).

Doesn't support: tradfns (∇R←X f Y), non-zero index origin (⎕IO), comparison tolerance (⎕CT), prototypes, modified assignment (x+←1), control structures (:If), object-oriented features, namespaces.

Used in Paul L Jackson's web site,, and

Offline usage

Download apl.js and run it with NodeJS to start a REPL:

node apl.js

An APL script can be given as argument:

node apl.js filename.apl

apl.js can be require()d as a CommonJS module from JavaScript:

var apl=require('./apl')
var r=apl('1 2 3+4 5 6')

or used in an HTML page:

<script src=''></script>
<script>var r=apl('1 2 3+4 5 6')</script>

Editor support