I just downloaded and installed IBM APL2 on my Windows box. '' prints a
blank line as I have been stating.
On Tue, May 27, 2014 at 3:32 PM, Blake McBride <blake1...@gmail.com> wrote:
> I don't know why it would be hard to rationalize. Here is your algorithm:
>
> if (printable value) {
> print value
> print cr
> }
>
> Here is the algorithm used by all APL's I've used:
>
> if (printable value) {
> print value
> }
> Print cr
>
>
> The advantage of the second algorithm is that if you are printing several
> values, you can see which is missing. Using your algorithm, null values
> don't get any display and you can get out of sync with regard to what was
> printed and which were null. Clearly the second is better.
>
> I challenge you, as I did in my last email, to show one instance in which
> a function would have '' but not want it to print.
>
> Blake
>
>
>
>
>
> On Tue, May 27, 2014 at 3:19 PM, Blake McBride <blake1...@gmail.com>wrote:
>
>> Dear David,
>>
>> First, I assure you, this is how it works.
>>
>> I do know of a 0⍴<value> idiom for branching and for nullifying a prior
>> value in a subsequent assignment. I am unaware of any need for that idiom
>> to prevent printing. Can you give me one example in a function?
>>
>> Thanks.
>>
>> Blake
>>
>>
>>
>> On Tue, May 27, 2014 at 2:32 PM, David B. Lamkins <dlamk...@gmail.com>wrote:
>>
>>> I find this confusing and counterintuitive.
>>>
>>> If displaying an empty vector causes the interpreter to emit a CR, what
>>> then becomes of the 0⍴<value> idiom commonly used to suppress display of
>>> <value>? Wouldn't your output be littered with spurious CRs every time
>>> your program executed such a line?
>>>
>>> I spent a half-hour digging through the IBM and ISO references, finding
>>> nothing on the subject of display of empty vectors.
>>>
>>> On Tue, 2014-05-27 at 13:04 -0500, Blake McBride wrote:
>>> > a. Neither an empty vector nor a vector of multiple elements has a CR
>>> > in it. The system prints the vector, and then prints a CR. CR gets
>>> > printed either way.
>>> >
>>> >
>>> > b. I found all these errors while porting my production code which
>>> > ran consistently over IBM APL and several other APL's. They all print
>>> > a blank line.
>>> >
>>> >
>>> > On Tue, May 27, 2014 at 12:57 PM, David B. Lamkins <da...@lamkins.net>
>>> > wrote:
>>> > How is that so? '' is an empty vector.
>>> >
>>> > On Mon, 2014-05-26 at 20:30 -0500, Blake McBride wrote:
>>> > > ∇test
>>> > > [1] '1'
>>> > > [2] ' '
>>> > > [3] '2'
>>> > > [4] ''
>>> > > [5] '3'
>>> > > [6] ∇
>>> > > test
>>> > > 1
>>> > >
>>> > > 2
>>> > > 3
>>> > >
>>> > >
>>> > >
>>> > >
>>> > > There should be a blank line between 2 and 3.
>>> > >
>>> > >
>>> > > Thanks.
>>> > >
>>> > >
>>> > > Blake
>>> > >
>>> > >
>>> >
>>> >
>>> >
>>> >
>>>
>>>
>>>
>>
>
