Re: [Bug-apl] indexing of the array

[Alexey Veretennikov]

Hi,

I've just checked, Dyalog APL returns exactly what you are expecting
from it:

      2 a[1]
2
      b←⍳5
      9 8 b
9 8  1 2 3 4 5 
      9 8 b[2]
8
      

Elias Mårtenson <address@hidden> writes:

> On 5 March 2016 at 19:12, Juergen Sauermann <address@hidden> wrote:
>
>
>  Hi Alexey,
>
>  the IBM APL2 binding rules say that [] binds stronger than vector notation 
> (IBM APL2
>  language reference page 34). That is, 
>
>  100 200[1] is 100 (200[1])
>
>  IBM APL2 behaves in the same way as GNU APL.
>
>
> At first I was confused about this (and even started writing this email 
> expressing that confusion). Then I
> realised that it is Dyalog that must have a very bizarre evaluator.
>
> What does the following do in Dyalog?
>
> a ← 1
> 2 a[1]
>
> If vector notation binds string that dereference, then this should return 2.
>
> But if that is the case, what does the following return?
>
> b ← ⍳5
> 9 8 b
> 9 8 b[2]
>
> Again, if Dyalog is consistent, it should return 8, and not 9 8 2 which is 
> the case in GNU APL.
>
> However, if Dyalog returns the same value as GNU APL, that means that the 
> parser changes the binding
> strength depending on the type of arguments. That sounds incredibly weird to 
> me.
>
> Regards,
> Elias
>

-- 
Br,
/Alexey