Raul Miller wrote:
>When you need to intermix three (or more) values in J,
>you have several options:
>
>[1] Compose some (or all) of them into a list
>[2] Use an explicit definition
>[3] recompute some of them
In the specific case of "three" values:
[4] Consider going the route adverb, or rather, adnoun, as I call
them in this case.
The adnoun gobbles up the first value, the derived verb the
second and third. Mind the positioning, though.
Within the primitives, the adverb Amend "}" is a good example:
'x' 1} 'ABC'
AxC
For practical purposes, this looks, works, and quacks like a three argument
function, certainly to many J newbies. While it isn't.
One of my pet adnouns is "concatenate two strings using a delimiter":
join =: 1 : 0
:
x , m , y
)
'wendy' '*'join 'lisa'
wendy*lisa
NB. more used like this:
'.'join&":/ 217 13 66 166
217.13.66.166
In the same vein, the following is a not very difficult exercise I
usually give in my commercial J courses. It is *always* both fun
and enlightning for the participants.
I give:
Write a conjunction C which allows you to do:
'foo' ','C'()' 'bar'
(foo),(bar)
' and 'C'|'/ 1;2;3; ;:'john paul george ringo'
|1| and |2| and |3| and |john| and |paul| and |george| and |ringo|
(I also use the exercise to talk about "creeping featurism"
and "coding economics" in the specific context of J.)
Exercise for the *advanced* Jer:
Don't send the (pretty trivial) spoiler to the above but keep the
answer to the above to yourself. Instead, code C tacitly. Keep
the answer to yourself.
Martin
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