3 :'a =. 1 label_. a + y' 4 5
----- Original Message ----- From: Jose Mario Quintana <[email protected]> To: Programming forum <[email protected]> Sent: Tuesday, April 19, 2016 7:19 PM Subject: Re: [Jprogramming] Adverbial Tacit Jym Dan, I am curious... Can you show us some examples of how the label-less label works as punctuation (separator)? PS. I enjoyed your ABRACADABRA sneaky solution [0] [0] [Jprogramming] ABRACADABRA http://www.jsoftware.com/pipermail/programming/2016-April/044950.html On Tue, Apr 12, 2016 at 10:49 AM, Dan Bron <[email protected]> wrote: > Pepe wrote: > > [0] [Jprogramming] Tacit adverb definitions? > > http://www.jsoftware.com/pipermail/programming/2006-July/002627.html > <http://www.jsoftware.com/pipermail/programming/2006-July/002627.html> > Ha, I’d forgotten about that. I remember having fun with it at the time. > > Not having to parenthesize the LHA to a conjunction under certain > conditions (the pertinent condition being insight under consideration in > this thread) came as a lovely little revelation when I was just hacking > around in the session manager. > > I can’t remember what I was playing with at the time, but I do remember > that little observation being an enjoyable outcome. It might have been when > I was exploring someone’s assertion (Randy’s, maybe, because of his deep > experience with APL?) that J evaluates strictly left-to-right. > > Anyway, it was in the era when I started to look at J’s grammar directly > (i.e. trying to actually understand $II.E) after spending years developing > a subconscious intuition for it. > > I’m still not nearly as conversant with J’s grammar, or parsers [in the > compiler sense] in general as Raul is, nor do I think I expect I ever will > be. I “get” it (as in, J’s evaluation of sentences I type rarely takes me > by surprise), but I’d have to put in some effort and thought in order to > explain it to a third party. And I would probably be forced to explain it > in more human / intuitive terms than what is spelled out in the parse table. > > In the same vein, though I don’t think it was at the same time, I also > remember a sense of satisfaction when I learned that 3 : ‘label_.’ (a > label-less label*) could be used as a minimal and semantically-transparent > J equivalent to APL’s diamond or C-like languages’ semicolons within > explicit definitions. > > That is, label_. acts as a logical line separator that forces the > expression on the left to be evaluated to completion before the expression > on its right is executed. > > This is distinct from normal labels, because if you wanted to use those, > you’d have to vary the label names if you wanted more than one line > separator in a single definition, which works, but feels like a hack. > > It’s also different from Ken’s original suggestion to use ]. (or, in > today’s terms, 2 : ‘v’), because while that works for (the majority of) > nouns and verbs, it does “the wrong thing” when one side or the other is an > operator (i.e. an adverb or conjunction). That is, its scope is limited. As > punctuation, label_. works for any wordclass. > > -Dan > > * https://en.wikipedia.org/wiki/The_Gateless_Gate < > https://en.wikipedia.org/wiki/The_Gateless_Gate> > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
