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apl functional symbol alpha

APL Functional Symbol Alpha

In APL, ⍺ marks a direct function's left input, and ⍵ marks its right. This paired notation grew out of APL's mathematical roots, when keyboards had few symbol keys.

Text symbol

Also called: APL alpha
Search it as: APL symbol · left argument · APL keyboard
Shows up in: Anything that takes text · its shape is whatever your font draws

What ⍺ means

It stands for the left argument of a direct function. In APL, a direct function is written in braces: in {⍺+⍵}, ⍺ receives the input on the left and ⍵ the input on the right. The pair lets one short definition name both inputs without ordinary variable names.

A function can also assign a default to ⍺ when no left input is supplied, letting one definition accept either one input or two. APL calls these monadic (one-input) and dyadic (two-input) calls.

How did APL's notation develop?

APL began as mathematical notation for procedures. Kenneth Iverson published that notation in 1962; implementations later turned it into a programming language. Keyboards and terminals had few symbol keys, so APL used compact signs for array operations and functions.

Earlier in APL's development, ⍺ and ⍵ also served other function roles; those functions were later withdrawn as the notation evolved.

A specialized programming convention: using ⍺ signals APL function syntax.

Don't confuse it with

Greek Small Letter Alpha

Greek α is an ordinary lowercase letter; ⍺ is a distinct APL character used for the left argument in a direct function.

Combination ideas

A direct function adding its left and right arguments.

Assigns a default value to the left argument.

Questions people ask

Why does ⍺ show as a box on some devices?

Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.

How to type ⍺

Windows (Word)

Alt+XType 237A, then Alt+X to get ⍺.

Windows

Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win + .).

macOS

Control+Command+SpaceOpen the character viewer and search “apl functional symbol alpha”.

Linux

Ctrl+Shift+UType 237a, then Enter or Space.

HTML

⍺

CSS

\237A

Dyalog US layout

In Dyalog's standard US mapping, press APL+a to enter ⍺.

RIDE or web editor

Use the editor's language bar, prefix key, or symbol completion; bindings vary by layout.

French AZERTY

The glyph uses the corresponding physical key position, which may be Q rather than A.

Codes and encoding1 code points

HTML decimal

⍺

HTML hex

⍺

CSS content

content: "\237A";

Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.

URL encoded

%E2%8D%BA

On screen

Code points

JS .length

UTF-8 bytes

A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.

Families this belongs to

Maths & numbers1,835 symbols

1️⃣📏📐✖️➕➖➗🟰♾️#️⃣*️⃣0️⃣