That "return nil" is clearly a typo and a further reflection of the poor
quality of that spec. I offer the following as proof that that comment is
a typo:
1. Look at the signature of ⎕ES at the beginning of 11.5.7. It says:
⎕ES B
it does not say:
Z←⎕ES B
like they do everywhere else when a quad function returns something.
2. In IBM APL 2 ⎕ES never returns a value.
3. Having ⎕ES return a value did cause me an unnecessary problem.
Where they day "return nil", they should have said "return".
Blake
On Mon, Jul 14, 2014 at 9:56 AM, Kacper Gutowski <[email protected]> wrote:
> On 2014-07-14 16:15:32, Juergen Sauermann wrote:
> > Since ⎕ES is not ISO-standard anyhow, I take the freedom to trade
> performance
> > for APL2 compatibility.
>
> But it is. See sections 11.5.7 and 11.6.5.
> And standard says it should return nil for empty right
> argument, which means not returning any value at all.
>
>
> -k
>
