APL left shoe stile

⍧ is a symbol from APL, a programming language that uses special signs to work with lists and tables of values. Its name, “left shoe stile,” describes a curved shape combined with a vertical stroke. The operation assigned to it is specific to the version of APL being used.

Text symbol

What ⍧ means

“Shoe” names the curved shape; “stile” names the vertical stroke.

APL character names often describe the parts of a sign. Here, “shoe” is a visual nickname, not a reference to footwear in the code. The combined shape is one character, rather than two signs you type separately.

APL grew out of Kenneth Iverson’s mathematical notation, presented in his 1962 book A Programming Language. It works with arrays: collections of values, such as lists and tables. Its distinctive symbols let programmers express operations compactly, but a character’s descriptive name does not tell you which operation a particular APL implementation gives it.

Part of the collection

🧑‍💻

Coding Emoji

Questions people ask

What does ⍧ do in actual code?

In dzaima/APL, as documented on 2026-10-08, one input produces yes/no markers for first appearances in a list. With two lists, it counts each left-side value’s occurrences in the right-side list. Check the APL implementation before applying those meanings elsewhere.