[Jprogramming] Strange(?) behavior of J

[Arnab Chakraborty]

Dear all,

    Here is a behavior that I noticed only recently, and it puzzles me a
lot:

  Let's say abc and xyz are not defined in my J session, and type just abc
by itself in a line. Of course, I get a value error. But if I type

xyz abc

then J does not produce any error, but simply echos back what I have typed!
I expected that J would start executing from the right, encounter abc, and
produce a value error. If I now define abc (say abc=. 0), then

xyz abc

produces a value error (expected) about xyz.

But why does J become silent in presence of multiple undefined symbols?