Am I correct that in your example, you are using Open (>) just for its rank
(monadic 0), and not for its verb (the inverse of Box)? That is
< @ i. @ ]"0 ( 2 3 4 )
+---+-----+-------+
|0 1|0 1 2|0 1 2 3|
+---+-----+-------+
would work as well. (Parens around the argument are needed to separate it from the
Rank conjunction ("0). I've also seen Same (]) used as a separator.) I think the
point is that you want the Box Atop Integers (< @ i.) to operate on the atoms of its
argument, not on the argument as a whole.
A more explicit way of saying you want a rank 0 verb is to use
(< @ i.)"0 ( 2 3 4 )
+---+-----+-------+
|0 1|0 1 2|0 1 2 3|
+---+-----+-------+
I find it confusing when I see Open used just for its rank. (But I'm learning.
:-) If my explanation is correct, maybe it will help someone else learn this
idiom.
... peter
Raul Miller wrote:
Here's a definition for at which works exactly like @
at=: 2 :'([: u v)"v
For example:'
<at i. at > 2 3 4
Now, looking at that, you may think that this means that [: is somehow
superior to @ but note that [: is not necessary
at=: 2 :'u@:v"v'
Note that in J, @: and @ (without the colon) are different words.
It's also possible to replace @: with an explicit definition, but
that's probably best left for another time.
FYI,
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