On Wed, 12/28/2022 01:58 PM Henry Rich wrote: > It is a canon of J that an empty list has no contents.
Aha, it's time to me to memorize it. Thank you. Now I see the reason of datatype leakage out which I've marked as "problem #2". Although it looks a little confusing: ]&.:(3&}.) 2 $ < 1 2 3 4 NB. (]) preserves a datatype ++++ |||| ++++ ] L: 0&.:(3&}.) 2 $ < 1 2 3 4 NB. (L:) preserves a datatype here (why?) ++++ |||| ++++ 1&+ L: 0&.:(3&}.) 2 $ < 1 2 3 4 NB. (L:) resets a datatype to default i.e. open (canon in action) 0 0 0 -- Regards, Igor ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
