What ⍸ means
With one input, ⍸ returns selected positions.
With positions numbered from 1, ⍸1 0 1 0 gives 1 3; count 2 repeats a position. In boundaries ⍸ values, the left input sets intervals for the right.
Kenneth Iverson began APL's notation for lists and tables in 1957; his book A Programming Language appeared in 1962; APL/360 brought wider implementation in 1968.
Don't confuse it with
1
Questions people ask
1Why 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.
More like this
10
How to type or find ⍸
- Search it as
- APL where · iota underbar · super-iota
- Shows up in
- Anything that takes text · its shape is whatever your font draws
Windows (Word)
Windows
macOS
HTML
⍸CSS
\2378TryAPL keyboard
APL MOOC guide:
PREFIX, Shift+I; or i, _, Tab.Dyalog Classic
Dyalog 20.0 guide:
⎕U2378 is the Classic fallback for Where.Codes and encoding1 code points
HTML decimal
⍸
HTML hex
⍸
CSS content
content: "\2378";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%8D%B8
1
On screen
1
Code points
1
JS .length
3
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.