Comments: The lamp symbol ⍝, formed by overstriking ∩ and ∘, signifies that what follows it is a comment, for illumination only and not to be executed; it may occur only as the first character in a statement, but may be used in defined functions.
The manual has at least one other “brush with humor”, depending on your sense of humor. Figure 1.2 depicts an APL\360 keyboard (which has a 5-pointed rather than 6-pointed star, by the way), accompanied with the following paragraph:
The special characters, most of which are produced with the keyboard shifted, generally have some mnemonic connection with their alphabetic or numeric correspondents. This may be appearance (⍵ over W), Greek-Roman equivalence (⍴ over R), sequence ( ≠ over 3 4 5 6 7 8), or some — possibly far fetched — relationship between the APL function represented by the symbol and the letter (* over P for power, ‘ over K for “kwote”, and ⌈ over S for ceiling).
Seems pretty hilarious to me.]]>
I also want to extend thanks to Roger for clarifying the discussion about zero and empty vectors. The quote was indeed from Donald McIntyre. I thought that Donald’s comment was brilliant, and I would certainly never claim any credit for that.]]>
Heh… Roger, you paper http://www.jsoftware.com/papers/log.htm is generating more buz an excitement than my logo. Nice job!]]>
The story is better than your quote indicates. From http://www.jsoftware.com/papers/APLQA.htm#nothing:
• [Commenting on the empty vector:] I think we have the Arabs to thank for inventing zero, but I know that we have Dr. Iverson to thank for inventing nothing.
— Donald McIntyre, APL Users Meeting, 1980-10]]>
Make me a WordPress plugin and I’ll turn it on.
Thanks for reading.]]>
In fact, it was Simon Garland who pointed out that we could also have gone with 6 points in our design.
We chose 5 because it looks better and we can see in a photo that Hal Carim posted in Facebook, a type ball with a star with 5 points…
And besides, to quote a story told by Jon McGrew – “We have the Arabs to thank for zero.”]]>