NB. j programmers MUST understand data flow.
   NB. x f^:3 y  differs from  (f&y)^:3 x

   f       NB. function f visualizes data routing.
3 : 0
'f';<y
:
x;'f';<y
)


   x       NB. nouns x and y are data.  x =: 'x'
X
   y
Y


   x f x f x f y   NB. GOAL.
+-+-+-------------+
|X|f|+-+-+-------+|
| | ||X|f|+-+-+-+||
| | || | ||X|f|Y|||
| | || | |+-+-+-+||
| | |+-+-+-------+|
+-+-+-------------+


   x f^:3 y        NB. CORRECT.
+-+-+-------------+
|X|f|+-+-+-------+|
| | ||X|f|+-+-+-+||
| | || | ||X|f|Y|||
| | || | |+-+-+-+||
| | |+-+-+-------+|
+-+-+-------------+


   (f&y)^:3 x      NB. WRONG
+-------------+-+-+
|+-------+-+-+|f|Y|
||+-+-+-+|f|Y|| | |
|||X|f|Y|| | || | |
||+-+-+-+| | || | |
|+-------+-+-+| | |
+-------------+-+-+



> From: Don Guinn <[email protected]>
> Subject: Re: [Jprogramming] recursive composition
> To: Programming forum <[email protected]>
> Message-ID:
>         <[email protected]>
> Content-Type: text/plain; charset=UTF-8
>
> Actually that isn't right. It should be (f&y)^:3 x  But don't get hung
> up on
> the difference. Look at ^: in the Dictionary.

----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm

Reply via email to