Here's a function to calculate the digital sum of a number in J:
digitalSum =: +/@:("."0)@":
If I use b.
to query the rank of this verb, I get _ 1 _
, i.e., infinite. (We can ignore the dyadic case since digitalSum
is not dyadic.)
I would like the monadic rank of this verb to be 0, as reported by b.
. The only way I know of to do this is to use a "shim", e.g.,
ds =: +/@:("."0)@": digitalSum =: ds"0
This works great, but I want to know whether it's the only way to do this, or if there's something else I'm missing.
Clarification
I just discovered how to change the rank of a verb that's defined thus:
digits =: 3 : 0 "0 "."0@": y )
Notice the "0
after the declaring 3 : 0
. You can put any adverb or conjunction you wish, and it will be applied to the verb as a whole. Pretty cool stuff!