Re: [Bug-apl] Outer product with replicate error

[Hans-Peter Sorge]

Am 15.05.2016 um 03:49 schrieb David B. Lamkins:
> While `$ info apl` speaks to the issues around function/operator ambiguity, 
> it does not make any mention of the outer product case.
> 
> I suspect that the failure of "outer product expand" is an oversight. This 
> case is disambiguated by noticing the outer product during the right-to-left 
> scan that GNU APL does anyway (step 3 in the referenced info page).
> 
> Outer product is a common idiom dating from the earliest days of APL. It 
> doesn't make any sense to require special (i.e. specific to GNU APL) syntax 
> for this particular case.
> 
> 
> On Sat, May 14, 2016 at 01:31:13PM -0500, Xiao-Yong Jin wrote:
>>
>>> On May 14, 2016, at 7:51 AM, David Tran <address@hidden> wrote:
>>>
>>> Hi,
>>>
>>> Newbie study "MasteringDyalogAPL"; got error on page #388 example:
>>>
>>>       3 0 2 ∘./ 5 1 7
>>> SYNTAX ERROR
>>>       3 0 2∘./5 1 7
>>>       ^      ^
>>>
>>> bug? ( or this is a specify feature of Dyalog and not APL2 ? )
>>
>> It’s documented in the info page of gnu apl.  A feature (bug?) of the parser 
>> treats / as an operator in this case.  Simple workaround would be
>>
>>       3 0 2 ∘.{⍺/⍵} 5 1 7
>>  5 5 5  1 1 1  7 7 7 
>>                      
>>  5 5    1 1    7 7   
>>
>> I have too limited experience to say whether it is good or bad.  Perhaps the 
>> parser should accept some exceptional cases?
>>
>> Best,
>> Xiao-Yong
>>
>>
>>
> 

Hi,

just to mention, there is an other difference in interpretation
regarding the scan operator GNU-APL vs IBM-APL.

GNU-APL:
      1 2 3 /¨ 4 5 6
 4  5 5  6 6 6

IBM-APL:

           1 2 3 /¨ 4 5 6
 4 4 4 4 4 4  5 5 5 5 5 5  6 6 6 6 6 6


Best Regards,
Hans-Peter