Re: [Bug-apl] quote-quote should display a blank line

[Blake McBride]

I am not sure I disagree with David, I am just arguing for consistency.  Thanks!

Blake

On Wed, May 28, 2014 at 5:02 AM, Juergen Sauermann <address@hidden> wrote:

Hi,

I agree with David that this is counter-intuitive, but I will
make it IBM APL2 compatible.

/// Jürgen

On 05/27/2014 11:37 PM, David B. Lamkins wrote:

On Tue, 2014-05-27 at 15:19 -0500, Blake McBride wrote:

Dear David,


First, I assure you, this is how it works.

I'm certainly not arguing the fact that this is the behavior you've seen
in other implementations.

I'm simply trying to reconcile the behavior you describe in light of my
long-ago experiences with APL 1 systems. If you take a look at the
FinnAPL Idiom list (which predates APL 2), they describe the 0⍴<value>
idiom for display suppression.

What I'd really like to see is something in either the IBM Reference
Manual or in the ISO Standard that support your assertion. I've been
unable to find either support or refutation in those references.

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?

Well, sure. This idiom is useful any time I'd like to evaluate a
value-returning function for its side effect(s) without also printing
the result of the function...

Thanks.


Blake




On Tue, May 27, 2014 at 2:32 PM, David B. Lamkins <address@hidden>
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
         <address@hidden>
         > 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
         >         >
         >         >
         >
         >
         >
         >