Roger’s post speculating on Ken Iverson’s favourite APL expression reminded me that one of the delegates at Dyalog ’14 conducted a quick survey to find the most popular primitive (thanks to Alex Weiner for taking the initiative here!). His findings are reproduced below:
9 votes: ⍴
8 votes: ⍳
6 votes: ⍨
4 votes: ⍠ ⍟ * ⎕
3 votes: ⌽ ¨ ⍎
2 votes: ⍺ ∇ ≢ ← ⊃ ⊢ ⍬
1 vote: ⍉ , ∊ ⍋ ∘ ∧ ⍲ ⊥ ⌈
Unfortunately there were no reasons given…is it because it’s a shape that’s pleasing to the eye, a really nifty piece of functionality or something more esoteric?
As for me, it’s easy – my favourite is the Log glyph (⍟). Not for a technical reason, although it performs a very useful function, nor due to its rather pleasing visual symmetry, but rather because of the way I was introduced to it. An APL virgin when I joined Dyalog 20 months ago, my first exercise was to familiarise myself with APL’s “beautiful squiggles”. When it came to the Log glyph I asked one of my colleagues a question and they dictated a line of APL to me to experiment with. As soon as they referred to ⍟ by its informal name of “splat” that was it, I was entranced. Any language that is so powerful, so concise and yet can make adults have passionate discussions involving the word “splat” has got me for life.
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I’m in good company – Roger Hui also identified the Log glyph as his favourite beautiful squiggle in his article “My favourite APL symbol” in Vector (volume 26 number 1, September 2013).
see http://archive.vector.org.uk/art10501040
There are many anecdotes on the names of APL glyphs and functions: ravel, ceiling, floor, nub, …; see http://www.jsoftware.com/papers/APLQA.htm#ravel and the ones immediately following that.