Kip The rule of 7+/-2 (title of Millers famous paper) is wrt the number of "chunks". One who is more practised builds better, longer, chunks. Perhaps associativity is one of those things which separates yeomen from masters.
Good writing builds chunks better in the readers mind. greg ~krsnadas.org -- from: km <[email protected]> to: "[email protected]" <[email protected]> date: 4 February 2013 08:10 subject: Re: [Jprogramming] Writing J Henry, this will be a long reply so please bear with me. It is comforting to a mathematician that @: is "associative". For example, |:@:(+:@:|.) i. 3 3 12 6 0 14 8 2 16 10 4 (|:@:+:)@:|. i. 3 3 12 6 0 14 8 2 16 10 4 "Associative" means moving the parentheses cannot change the answer. (I have not proved @: is associative -- this is an example to illustrate the meaning of "associative".) But @ is NOT associative: |:@(+:@|.) i. 3 3 12 6 0 14 8 2 16 10 4 (|:@+:)@|. i. 3 3 12 14 16 6 8 10 0 2 4 "Not associative" means moving the parentheses can change the answer. (This example proves @ is not associative.) The fact that @ is not associative makes me pay more attention when I am using it, as compared to using @: . Kip -- from: Henry Rich <[email protected]> to: [email protected] date: 4 February 2013 05:28 subject: Re: [Jprogramming] Writing J Perhaps @ should not count as a 'thing' here. The language could have been defined so that u v meant the composition of u and v; is the space a thing then? How many 'things' is f g h ? For my mental load, parentheses are things; @ and @: nothing; fork something; hook something more. Henry Rich -- from: km <[email protected]> to: "[email protected]" <[email protected]> date: 3 February 2013 21:21 subject: Re: [Jprogramming] Writing J And we can notice that with v c v c v c v (four verbs and three conjunctions) we reach your count of seven! Incidentally, replacing |. with ] improves my examples: -@]/ 1 2 3 3 -@(]/) 1 2 3 _3 -- from: Tracy Harms <[email protected]> to: [email protected] date: 3 February 2013 19:28 subject: Re: [Jprogramming] Writing J My experience has been that my openness to long chains of modifiers has increased as I get better at reading J. Also, I find value in the widespread idea that seven, plus or minus two, is a count of things that people can keep in mind simultaneously. I don't think it's worth proposing specific standards for what counts as "a thing" for such tallying, but do think it's worth noticing as a rough guide. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
