I have been looking at how Dyalog does it, and their implementation is even
more strange. I have to agree with your assessment.
Last night as I was about to go to sleep I thought about a change that
could make the use of "side-effect-only" lambdas much more logical and
functional. It sounded great to my inner mind before I went to sleep, so at
least I feel it should be discussed here.
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.
The justification for this is as follows:
- Niladic functions can't be passed to operators, so they are useless
for that.
- If the niladic lambda is parsed as a monadic function, things like
this would be possible again: {⎕←'hello'} REPEAT 10
- Thus, the only use for niladic lambdas would be to assign them to a
name: foo←{2}
- To deal with the above, there are two different approaches:
1. Such assignment will result in foo being a dyadic function, or
2. A niladic lambda can remain niladic when assigned to a variable
Regards,
Elias
On 5 August 2014 23:47, Juergen Sauermann <juergen.sauerm...@t-online.de>
wrote:
> Hi,
>
> this is how I read the ISO standard. If a statement that is valid per ISO
> returns
> a wrong result then I consider that a fault that should be (and was) fixed.
>
> If that conflicts with an intended use of a non-standard extension like
> the ⍣ operator then I
> would rate that as simply bad luck (as opposed to a fault).
>
> /// Jürgen
>
>
>
> On 08/05/2014 04:40 PM, Elias Mårtenson wrote:
>
> Are you sure we want to fix that though? Things like the power operator
> (once we have it) will not work right (since it's seems to be often used to
> execute a niladic function a certain number of times.
>
> The SQL∆WithTransaction will have the same problem.
>
> The workaround seems to be a bit ugly, like prefixing the lambda
> function with ⍵⊢
>
> Regards,
> Elias
>
>
> On 5 August 2014 22:07, Juergen Sauermann <juergen.sauerm...@t-online.de>
> wrote:
>
>> Hi David,
>>
>> thanks, fixed in SVN 417. Unfortunately, as a consequence, it is no
>> longer possible to pass a niladic function to an operator.
>>
>> /// Jürgen
>>
>>
>>
>> On 08/05/2014 09:39 AM, David B. Lamkins wrote:
>>
>>> Maybe I've misunderstood some APL2 corner case, but the behavior of the
>>> attached program seems wrong.
>>>
>>>
>>
>>
>
>
