Re: [Bug-apl] IOTA

[Jay Foad]

On 3 March 2016 at 11:40, Juergen Sauermann
<address@hidden> wrote:
> Therefore I believe Elias' statement
>
> My understanding was that (⊂⊂x)≡⊂x for all x?
>
> is correct as far as ISO, IBM APL2, and GNU APL are concerned.

It is clearly not true in APL2!

      x←1 2 3
      (⊂⊂x)≡⊂x
0

(Same result in NARS2000 and Dyalog.)

It is not true according to the ISO spec either, because ⊂1 2 3 is not
a simple scalar. The relevant ISO definition is:

"Simple: An array is simple if each item of its ravel-list is either a
character or a number."

... but ⊂1 2 3 has a single item in its ravel list, which is the array
1 2 3, which is not "either a character or a number."

Jay.