Re: [Bug-apl] IOTA

[Juergen Sauermann]

Hi, the IBM APL2 language reference says (page 111): If R is a simple scalar, ⊂R is R. If R is not a simple scalar, the depth of R is 1+≡R. And the ISO standard says the same (page 169): Z ← ⊂B  Note: If B is a simple-scalar, Z is B. 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. /// Jürgen On 03/03/2016 10:21 AM, Jay Foad wrote: On 3 March 2016 at 08:12, Elias Mårtenson <loke...@gmail.com> wrote: What is the purpose of the double-enclose ⊂⊂⍬ ? My understanding was that (⊂⊂x)≡⊂x for all x? No! ⊂ is a no-op on simple scalars like 42, but not on enclosures like ⊂⍬. You can enclose most arrays (i.e. anything except simple scalars) as many times as you like, and they keep getting deeper and deeper. Hmm, now I see that GNU APL seems to be broken. In APL2 and Dyalog and NARS2000 I get: ≡⊂⊂⊂⊂⊂⊂⊂⊂⊂'elias' 10 But in GNU APL: ≡⊂⊂⊂⊂⊂⊂⊂⊂⊂'elias' 2 Jay.