An undefined name is assumed to be a verb, so tally never gets
executed. I use
ifdefined_z_ =: 0 <: [: 4!:0 <
ifdefined 'a'
0
ifdefined 'ifdefined'
1
Henry Rich
On 8/3/2020 12:52 PM, Brian Schott wrote:
This thread hints at a problem I am having.
In particular the link suggested by Henry
https://code.jsoftware.com/wiki/Vocabulary/ErrorMessages#value
My problem is that I want to detect an error caused by an undefined noun
but my attempt does not produce the desired error using :: .
For example in the example below, although `a` is undefined, I do not get
the desired result, 0, from my verb `tally` when I execute `tally a`.
How can I define tally to produce 0 for an undefined argument. Or how do I
detect an undefined argument, in general? I have considered using a try.
... catch. in an explicit definition, but to me that seems unnecessary.
a
|value error: a
tally =: # :: 0:
tally i. 4
4
tally a
tally a
On Wed, Nov 6, 2019 at 5:11 AM Henry Rich <henryhr...@gmail.com> wrote:
https://code.jsoftware.com/wiki/Vocabulary/ErrorMessages#value
Henry Rich
On 11/6/2019 4:26 AM, Arnab Chakraborty wrote:
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?
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