But having {⎕←'foo'} REPEAT 10 result in an error is certainly surprising
to me. Also, if you look at where lambdas are actually used, the current
behaviour results in more surprises than the Dyalog model. Even
disregarding the surprises part (which I can agree is often a matter of
personal taste), the Dyalog model is distinctly more *useful*.
And, one could argue that knowing that lambdas are always variadic is quite
consistent in itself.
Regards,
Elias
On 7 August 2014 20:56, Juergen Sauermann <juergen.sauerm...@t-online.de>
wrote:
> Hi,
>
> for me it is not at all clear why *{1} 0* should eat (and discard) its
> right argument.
>
> In other words why would *{1} 0 *behave differently than *N 0 *with *N*
> being a niladic function?
>
> That would create new rules in the APL syntax without a need. I would
> rather opt for David's
> "principle of least surprises" than for Dyalog compatibility in this case.
>
> /// Jürgen
>
>
>
> On 08/07/2014 10:43 AM, Elias Mårtenson wrote:
>
> Jay,
>
> That makes sense. So the only benefit of the GNU APL approach is that it
> allows the definition of niladic functions by assigning from a lambda.
>
> My personal opinion is that that's barely a benefit, and that the Dyalog
> approach is much better.
>
> Perhaps Jürgen is willing to reconsider?
>
> Regards,
> Elias
>
>
> On 7 August 2014 16:35, Jay Foad <jay.f...@gmail.com> wrote:
>
>> Elias,
>>
>> There is no such thing as a niladic lambda in Dyalog.
>>
>> In Dyalog "niladic lambda functions [are] not [...] allowed at all.
>> Instead, they [are] interpreted as monadic functions that ignore their
>> argument."
>>
>> So {1} is a monadic function. You can evaluate it by applying it to an
>> argument:
>>
>> {1}0
>> 1
>>
>> (Actually in Dyalog lambdas are not monadic or dyadic. They are all
>> "ambivalent". If they do not refer to ⍺ then any left argument will be
>> ignored.)
>>
>> Jay.
>>
>> On 7 August 2014 09:09, Elias Mårtenson <loke...@gmail.com> wrote:
>> > Jay,
>> >
>> > I also noticed that Dyalog does not allow self-evaluation of niladic
>> > lambdas. I.e. the expression {1} on its own does not evaluate to 1, but
>> > rather to something else (it's displayed as {1}, and I'm not sure you
>> can do
>> > anything with it other than assigning it to a variable).
>> >
>> > Regards,
>> > Elias
>> >
>> >
>> > On 7 August 2014 16:00, Jay Foad <jay.f...@gmail.com> wrote:
>> >>
>> >> On 6 August 2014 14:15, Elias Mårtenson <loke...@gmail.com> wrote:
>> >> > My suggestion is that niladic lambda functions will not be allowed at
>> >> > all.
>> >> > Instead, they will be interpreted as monadic functions that ignore
>> their
>> >> > argument.
>> >>
>> >> That's consistent with the behaviour of Dyalog.
>> >>
>> >> Jay.
>> >
>> >
>>
>
>
>
