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 <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 > > > > > > > > > > > > > > > > > > >
