APL, a punning language

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APL, a punning language

Postby Roger|Dyalog on Sun May 03, 2020 8:25 pm

APL is richly expressive and is therefore well-suited for puns. Herewith a few puns on APL characters.

From A Dictionary of APL [Iverson 1987, Table 1], a list of APL characters, their names, and ASCII transliterations:
↑ Pike
↓ Spike
⍋ Pine
⍒ Spine

From My Favorite APL Symbol [Hui 2013]:
Reasons for Liking ⍟
• It’s kind of cute, possessing a radial symmetry.
• It denotes a function for which conventional mathematical notation [Abramowitz and Stegun 1964, §4.1] does not have a good symbol:
⍟y ↔ ln y or log y
x⍟y ↔ logx y
• It alludes to 0=1+*○0j1, the most beautiful equation in all of mathematics [Hui 2010], relating in one short phrase the fundamental quantities 0, 1, e, π, and 0j1 and the basic operations plus, times, and exponentiation.
• It is a visual pun—the symbol looks like the cross section of a felled tree, i.e. a log [McDonnell 1977].

From [Hui and Kromberg 2020], discussing index:
Other dialects use ⌷, Unicode code point U+2337. It is nicely mnemonic (looks like I for index, get it?) and is likely a typographical, notational, and historical pun: ⌷ is [ overstruck with ] on the IBM 2741 terminal (§6.3.1).

Of course, APL puns are not restricted to just puns on characters. You can find more puns in the Dyalog blog post APL Puns from 2015.
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