If it's helpful for the presentation, I wrote up how the parentheses
nesting idiom looks in a few other languages:
There are two relevant concepts - the array thinking and the implementation
J
+/\(1 _1 0){~'{}' i. '@{ foo; if (abc) { if (q) { m; } } }'
0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 2 2 1 1 0
Javascript
var runsum=0;'@{ foo; if (abc) { if (q) { m; } }
}'.split('').map(function(x) { var opp={'{':1,'}':-1}; return
opp[x]||0; }).map(function(x) { runsum = x+runsum; return runsum; })
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2,
2, 2, 2, 3, 3, 3, 3, 3, 2, 2, 1, 1, 0
PicoLisp
(reverse (mapcon '((X) (list (apply + X))) (reverse (mapcar '((X)
(cond ((= X "{") 1) ((= X "}") -1) (T 0))) (chop "@{ foo; if (abc) {
if (q) { m; } } }")) ) ))
(0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 2 2 1 1 0)
http://csilo.com/!article?2014/01/15/J-vs-Javascript-vs-PicoLisp-short-comparison
On Fri, Jan 17, 2014 at 10:41 AM, Devon McCormick <[email protected]> wrote:
> I'll be talking on J to a meetup here in New York this coming Tuesday -
> http://www.meetup.com/7-Languages-in-7-Months-NYC/ - so I've been watching
> the "fork examples" discussion w/some interest.
>
> I did a dry run of my talk at NYCJUG this past Tuesday and, at that time, I
> was looking to build up to a final, mind-blowing example like the
> Newton-Raphson iterator, but now am thinking that that's too "tricky" and
> what I'd really like to do is go into detail on some simpler examples. Joe
> Bogner's interest in the parenthesis-nesting idiom reminded me of how
> innovative the array approach still is, so I'm definitely using that one.
>
> David Lambert, who was at the NYCJUG meeting has also given me a couple of
> good ideas since then but I'm interested in anyone else's favorite J idiom
> - "Jems" as Dan would have it - that illustrate the usefulness of array
> thinking.
>
> Thanks,
>
> Devon
> --
> Devon McCormick, CFA
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
