J Dirty hack

Thanks to dr_klm, who implicitly pointed to the unexpected feature:

Here is the expected behavior of the fork and operator @

load 'system/packages/misc/fndisplay.ijs'
setfnform 'Jv'
defverbs 'F G H'
defnouns 'y'

(F G@H ]) y
+---------------+
|G_ (F_ y) _H_ y|
+---------------+

If it were not for..

Exetuting:

  (2&+@i.@#  %@(+/\) ]) i.4
    1 0.333333 0.2
0.333333 0.166667   0
0.166667        0   0
    0        0   0
  %((2&+@i.@# i.4) (+/\) (] i.4))
    1 0.333333 0.2
0.333333 0.166667   _
0.166667        _   _
    _        _   _

Obviously, records that supposed to be equivalent are really not, due to the presence of the implicit operation — filling with zeros.

I doubt whether I should enjoy this feature, or not. If there is no trouble in recognition of the operation in the code, it can even be a beautiful solution.