Pattern "left join"---same frame of mind as when
we staple a couple of pages together (in the
upper left hand corner, as we usually do).
-M
At 2016-06-14 03:07, you wrote:
Perhaps easier to see with more
formal/expressive verbs: in =. 1 :'[,''
'',u,'' '',]' NB. String to infix
function ('f0'in)`('f1'in)`('f2'in)/ 'abcde'
a f0 b f1 c f2 d f0 e The verbs in the gerund
are arranged from left to right starting at the
beginning of the array, while application (as in
the non-gerund case) proceeds from right to
left. I would avoid calling either of these
things "unrolling" without further explanation
as it's not clear which that would mean. Dan's
example has typos, and his wording is vague
enough that I can't tell whether it is correct.
Marshall On Tue, Jun 14, 2016 at 02:21:37AM
+0000, 'Pascal Jasmin' via Programming wrote: >
+`-/ 1 2 3 > 0 > +`+`-/ 1 2 3 > 6 > > > I call
this as being inserted between items on a right
to left basis. > > 1 + 2 - 3 + 4 > > +`-/ 1 2 3
4 > _4 > +`-/ 1 2 > 3 > > > > ----- Original
Message ----- > From: Dan Bron <[email protected]> > To:
J Programming <[email protected]> >
Sent: Monday, June 13, 2016 9:04 PM > Subject:
Re: [Jprogramming] Am I understanding m/y ? > >
Louis wrote: > > > There was some talk a while
ago about the ambiguity of the dictionary about
the direction of gerund insertion. Reading
through the first pages of Iverson's Concrete
Math Companion, I stumbled on a snippet of J
that dates back to 2002 and was written by
Iverson at the bottom of page 6: > > > >
http://www.jsoftware.com/books/pdf/cmc.pdf
<http://www.jsoftware.com/books/pdf/cmc.pdf> > >
> > According to this source, gerunds do indeed
"unroll" from left to right correctly in the
current implementation. > > > Iâm also on
mobile, so forgive my terse answer and potential
misunderstanding of your question, but
yes: > > > v0`v1`v2`v3/ y > > is
indeed: > >
(_8{y) v2 (_7{y) v3
(_6{y) v0 (_5{y) v1 (_4{y) v2 (_3{y) v1 (_2{y)
v0 _1{y > > That is, the insertion of verbs
starts at the rightmost (last) elements of y,
but the leftmost (first) elements of the gerund
G, where G/y . > > The rationale for this is
left as an exercise for a less lazy respondent
(though the right-to-left nature of insertion in
y should be familiar to veteran Jâers). > >
-Dan > > > >
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