Re: ¨ (each) on defined function on array of empty arrays

[Dr . Jürgen Sauermann]

Hi again, fixed in SVN 1289. Thanks, Jürgen On 5/31/20 12:48 PM, Dr. Jürgen Sauermann wrote: Hi Ben, see below. Jürgen On 5/30/20 6:46 PM, Ben Harris wrote: [ Not sure if you deliberately left bug-apl off the recipient list: feel free to forward to the list if you want. ] No. I probably just pushed reply instead of reply-to-all. I normally want all communication to be as transparent as possible, but sometimes I fail to  achieve that. On Sat, 30 May 2020, Dr. Jürgen Sauermann wrote: not sure if it is an error. I suspect that the reason for the difference you see is caused by the fact that the primitive ≡ and your defined function 'depth' have different fill functions. The fill function is a function applied to the empty arguments. The fill function for ≡ is ≡ while the fill function for any defined function (including depth) is { ⍵ } (or Z←B as IBM phrases it). I've looked briefly at the manual before realising that fill functions aren't relevant here.  The fill function is necessary when the right argument (R) to ¨ is empty, but here R is not empty, it's an array with two elements.  Each of those elements is empty, but R itself is not. So I think "each" should just pass each empty array to ≡ or depth as appropriate and it's only those functions that should pay attention to the emptiness of the arrays.  The description of the calling sequence for a defined function doesn't say anything special about empty arrays, so the empty arrays should just be passed on to ≡,so the two results should be the same. I see. I will have another look at it, I did some tests with IBM APL2 after reading your first mail, but everything related to empty values (or non-empty values containing empty values) is difficult to distinguish. Fill functions would matter if I evaluated ≡¨a or depth¨a, and indeed those differ (and I think give the correct results).