On 1/22/2019 0:17 AM, Henry Rich wrote: > Opening (,<0$a:) produces a empty list of boxes, which behaves > differently as the left argument to { than an empty numeric list.
Thank you, Henry and Bill. I've forgot about useful foreign 5!:5 and relied too heavily on match result. Now the reason of the error is clear to me. -- Regards, Igor ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm