[Jprogramming] @ and @: (atop and at)

[Brian Schott]

   #@:>@:;:'a man a plan a canal'     NB. 1
6
   #@:>@;:'a man a plan a canal'     NB. 2
6
   #@>@;:'a man a plan a canal'     NB. 3
1 3 1 4 1 5
   #@>@:;:'a man a plan a canal'     NB. 4
1 3 1 4 1 5
   #@(>@:;:)'a man a plan a canal'     NB. 5
6
   #@(>@;:)'a man a plan a canal'     NB. 6
6

These examples are hard for me to grok.
Comparing 1 and 2 and 4 suggests that either order is important or that #
is effected and > is not.
Example 6 suggests that parentheses can produce results like @: especially
when compared with 2.

My experience in the past has been especially puzzling when I try to
combine atop with the MIDDLE TINE result of a fork as the following
examples attempt to cover. In these example I use at and atop in the names
to reflect the use of @ and @: ; I use app in the names to reflect the use
of append . These examples --especially the comparison between the
application of meanatapp and meanatappparen -- are confusing.

But also it surprises me that in the last 2 examples the overall tally of 4
is achieved, except that atop takes on the rank of its predecessor, where
in these 2 last examples the predecessor verbs (append) are infinite rank.

   mean =: +/ % #
   mean i. 3 4
4 5 6 7
   meanat =: +/ #@:% #
   meanat i. 3 4
4
   meanatop =: +/ #@% #
   meanatop i. 3 4
1 1 1 1
   meanatapp =: +/ #@:,@% #      NB. *****focus on this one, and ...
   meanatapp i. 3 4
1 1 1 1
   meanatopapp =: +/ #@,@% #
   meanatopapp i. 3 4
1 1 1 1

   meanatappparen =: +/ #@:(,@%) #   NB. *****this one
   meanatappparen i. 3 4
4
   meanatopappparen =: +/ #@(,@%) #
   meanatopappparen i. 3 4
1 1 1 1

   meanatappat =: +/ #@:,@:% #
   meanatappat i. 3 4
4
   meanatappatop =: +/ #@,@:% #
   meanatappatop i. 3 4
4
   meanatappparenatop =: +/ #@(,@:%) #
   meanatappparenatop i. 3 4
4




On Fri, Jan 22, 2016 at 4:50 AM, Linda A Alvord <lindaalvord at verizon.net>
wrote:
I think I finally understand the difference!

    A=:'a man a plan a canal'
   ;:A
┌─┬───┬─┬────┬─┬─────┐
│a│man│a│plan│a│canal│
└─┴───┴─┴────┴─┴─────┘
   f=: 13 :'#>;:y'
   g=: 13 :'#@>;:y'
   h=: 13 :'#@:>;:y'


-- 
(B=) <-----my sig
Brian Schott