APL Thorn

⍕ is APL’s formatting function: on its own it turns a value into text; a value on its left can control the format. APL is a programming language that uses compact symbols for mathematical procedures and array operations. Dyalog 19.0 calls this function Thorn; Unicode labels the glyph by its shape.

Text symbol

What ⍕ means

It formats values as text. This APL format symbol is a built-in function in Dyalog 19.0: ⍕A formats A as character data (text), and X⍕A uses X as the formatting instruction for A. A and X are placeholders for values; X sets the format.

Kenneth Iverson’s notation began as mathematical notation in 1957 and became APL, a programming language, in 1966.

How do I type ⍕?

On IBM APL2, use Alt-] on its APL keyboard layout.

⍕ signals APL code or a discussion of array formatting; it is not a general-purpose mathematical sign.

In ordinary chat, a bare ⍕ assumes the reader knows APL; add a few words of context.

Questions people ask

Why is ⍕ called Thorn?

Dyalog 19.0 uses Thorn as the APL function name, while Unicode describes the glyph by its shape. A 2000 APL working-group document records a disagreement between two APL symbol-naming conventions, Bosworth and London.