> It would be enlightening to all of us (or just me) if someone could point
out an exception to the heuristic, or provide a more accurate one.
Consider the following right argument,
Y=. 5!:2@:<'toJ'
the next sentence just echoes the arguments taken by the verb ([echo) and
reproduces Y,
([echo) L:_2 Y
┌─────────────────────┬─┐
│┌───────────────┬─┬─┐│}│
││┌──┬─┬────────┐│@│]││ │
│││I.│@│┌──┬─┬─┐││ │ ││ │
│││ │ ││e.│&│ │││ │ ││ │
│││ │ │└──┴─┴─┘││ │ ││ │
││└──┴─┴────────┘│ │ ││ │
│└───────────────┴─┴─┘│ │
└─────────────────────┴─┘
]
@:
┌─────┬──────────────────────┐
│┌─┬─┐│┌──┬─┬───────────────┐│
││#│~│││-.│@│┌─────────┬─┬─┐││
│└─┴─┘││ │ ││┌──┬─┬──┐│@│,│││
│ ││ │ │││ │&│E.││ │ │││
│ ││ │ ││└──┴─┴──┘│ │ │││
│ ││ │ │└─────────┴─┴─┘││
│ │└──┴─┴───────────────┘│
└─────┴──────────────────────┘
┌───────────────────────────────┬──┬──────────────────────────────┐
│┌─┬─────────────────────────┬─┐│@:│┌─────┬──────────────────────┐│
││ │┌─────────────────────┬─┐│]││ ││┌─┬─┐│┌──┬─┬───────────────┐││
││ ││┌───────────────┬─┬─┐│}││ ││ │││#│~│││-.│@│┌─────────┬─┬─┐│││
││ │││┌──┬─┬────────┐│@│]││ ││ ││ ││└─┴─┘││ │ ││┌──┬─┬──┐│@│,││││
││ ││││I.│@│┌──┬─┬─┐││ │ ││ ││ ││ ││ ││ │ │││ │&│E.││ │ ││││
││ ││││ │ ││e.│&│ │││ │ ││ ││ ││ ││ ││ │ ││└──┴─┴──┘│ │ ││││
││ ││││ │ │└──┴─┴─┘││ │ ││ ││ ││ ││ ││ │ │└─────────┴─┴─┘│││
││ │││└──┴─┴────────┘│ │ ││ ││ ││ ││ │└──┴─┴───────────────┘││
││ ││└───────────────┴─┴─┘│ ││ ││ │└─────┴──────────────────────┘│
││ │└─────────────────────┴─┘│ ││ │ │
│└─┴─────────────────────────┴─┘│ │ │
└───────────────────────────────┴──┴──────────────────────────────┘
The equivalent form, according to the DoJ does the same,
([echo) L:(0>.(L.Y)-2) Y
┌─────────────────────┬─┐
│┌───────────────┬─┬─┐│}│
││┌──┬─┬────────┐│@│]││ │
│││I.│@│┌──┬─┬─┐││ │ ││ │
│││ │ ││e.│&│ │││ │ ││ │
│││ │ │└──┴─┴─┘││ │ ││ │
││└──┴─┴────────┘│ │ ││ │
│└───────────────┴─┴─┘│ │
└─────────────────────┴─┘
]
@:
┌─────┬──────────────────────┐
│┌─┬─┐│┌──┬─┬───────────────┐│
││#│~│││-.│@│┌─────────┬─┬─┐││
│└─┴─┘││ │ ││┌──┬─┬──┐│@│,│││
│ ││ │ │││ │&│E.││ │ │││
│ ││ │ ││└──┴─┴──┘│ │ │││
│ ││ │ │└─────────┴─┴─┘││
│ │└──┴─┴───────────────┘│
└─────┴──────────────────────┘
┌───────────────────────────────┬──┬──────────────────────────────┐
│┌─┬─────────────────────────┬─┐│@:│┌─────┬──────────────────────┐│
││ │┌─────────────────────┬─┐│]││ ││┌─┬─┐│┌──┬─┬───────────────┐││
││ ││┌───────────────┬─┬─┐│}││ ││ │││#│~│││-.│@│┌─────────┬─┬─┐│││
││ │││┌──┬─┬────────┐│@│]││ ││ ││ ││└─┴─┘││ │ ││┌──┬─┬──┐│@│,││││
││ ││││I.│@│┌──┬─┬─┐││ │ ││ ││ ││ ││ ││ │ │││ │&│E.││ │ ││││
││ ││││ │ ││e.│&│ │││ │ ││ ││ ││ ││ ││ │ ││└──┴─┴──┘│ │ ││││
││ ││││ │ │└──┴─┴─┘││ │ ││ ││ ││ ││ ││ │ │└─────────┴─┴─┘│││
││ │││└──┴─┴────────┘│ │ ││ ││ ││ ││ │└──┴─┴───────────────┘││
││ ││└───────────────┴─┴─┘│ ││ ││ │└─────┴──────────────────────┘│
││ │└─────────────────────┴─┘│ ││ │ │
│└─┴─────────────────────────┴─┘│ │ │
└───────────────────────────────┴──┴──────────────────────────────┘
The levels down of the leaves of Y correspond to
$L:1 {:: Y
┌─────────────────────────────┬─┬───────────────────────────┐
│┌─┬───────────────────────┬─┐│1│┌─────┬───────────────────┐│
││2│┌───────────────────┬─┐│2││ ││┌─┬─┐│┌─┬─┬─────────────┐││
││ ││┌─────────────┬─┬─┐│3││ ││ │││3│3│││3│3│┌───────┬─┬─┐│││
││ │││┌─┬─┬───────┐│4│4││ ││ ││ ││└─┴─┘││ │ ││┌─┬─┬─┐│4│4││││
││ ││││5│5│┌─┬─┬─┐││ │ ││ ││ ││ ││ ││ │ │││5│5│5││ │ ││││
││ ││││ │ ││6│6│6│││ │ ││ ││ ││ ││ ││ │ ││└─┴─┴─┘│ │ ││││
││ ││││ │ │└─┴─┴─┘││ │ ││ ││ ││ ││ ││ │ │└───────┴─┴─┘│││
││ │││└─┴─┴───────┘│ │ ││ ││ ││ ││ │└─┴─┴─────────────┘││
││ ││└─────────────┴─┴─┘│ ││ ││ │└─────┴───────────────────┘│
││ │└───────────────────┴─┘│ ││ │ │
│└─┴───────────────────────┴─┘│ │ │
└─────────────────────────────┴─┴───────────────────────────┘
It interesting to note that the level down 2 branch,
(0;1) {:: Y
┌─────────────────────┬─┐
│┌───────────────┬─┬─┐│}│
││┌──┬─┬────────┐│@│]││ │
│││I.│@│┌──┬─┬─┐││ │ ││ │
│││ │ ││e.│&│ │││ │ ││ │
│││ │ │└──┴─┴─┘││ │ ││ │
││└──┴─┴────────┘│ │ ││ │
│└───────────────┴─┴─┘│ │
└─────────────────────┴─┘
is echoed; however, the level down 2 branch,
(2;0) {:: Y
┌─┬─┐
│#│~│
└─┴─┘
is not echoed.
If I had to verbalize the monadic case of L: for a negative (right)
argument (-r) I would base it on the equivalent form (L:(0>.(L.Y)-r),
assuming that it always hols); for example,
It is the level at (L:) the maximum between 0 and the difference between
the level (L.) of the argument (Y) of the verb produced (u L:(-r)) and the
absolute value of its right argument (-r).
At any rate, for what is worth, I agree with your biggest point.
On Sun, Jul 29, 2018 at 5:51 PM, 'Pascal Jasmin' via Programming <
[email protected]> wrote:
>
>
> so L:_2 would be "one level down from top level". Its not quite the same
> as "double each"
>
> $&.>&.> t
>
> ┌──┬───────┐
>
> │┌┐│┌─┬─┬─┐│
>
> │││││3│2│2││
>
> │└┘│└─┴─┴─┘│
>
> └──┴───────┘
>
> I would verbalize that as "at -2 levels or operate on null"
>
> regarding: " if there is an appropriate "-2" level then apply there, else
> apply at maximum depth."
>
> that feels like the current interpretation, and certainly if I have an
> urge to apply the above heuristic, then L:_2 is what I would try.
>
> It would be enlightening to all of us (or just me) if someone could point
> out an exception to the heuristic, or provide a more accurate one.
>
> I'd say my biggest point is that if you want a version of L: (and I think
> such a version is very useful) that leaves "levels" unchanged/unprocessed
> if they do not exist, then something like L:: (a new definition) is
> worthwhile.
>
>
>
> On Sunday, July 29, 2018, 5:29:57 p.m. EDT, Henry Rich <
> [email protected]> wrote:
>
>
>
>
>
> " if there is an appropriate "-3" level then apply there, else apply at
> maximum depth."
>
> As a rule describing current behavior, this is wrong. It suffers from a
> couple of undefined terms: (1) what is -3 level? (2) what is maximum depth?
>
> If -3 level means "3 levels down from the top" (or equivalently
> "enclosed by 3 boxes"), it has a more serious problem: the system
> doesn't do that currently.
>
> Henry Rich
>
> On 7/29/2018 5:22 PM, 'Pascal Jasmin' via Programming wrote:
> >
> > From your wiki entry, this is the current behaviout:
> >
> > $L:_3 t
> >
> > ┌─┬─────────────┐
> >
> > │1│┌───────┬─┬─┐│
> >
> > │ ││┌─┬─┬─┐│2│2││
> >
> > │ │││3│1│2││ │ ││
> >
> > │ ││└─┴─┴─┘│ │ ││
> >
> > │ │└───────┴─┴─┘│
> >
> > └─┴─────────────┘
> >
> > which is quite reasonable: " if there is an appropriate "-3" level then
> apply there, else apply at maximum depth."
> >
> > The behaviour to leave unchanged if "no such level exists" is useful,
> but perhaps a new primitive "L::" would be the appropriate path.
> >
> > L::2 would also leave items that do not have such depth unchanged.
> >
> > There doesn't seem to be a "magic reason" for negative n argument to
> have different behaviour.
> >
> >
> >
> > On Saturday, July 28, 2018, 7:42:39 p.m. EDT, Henry Rich <
> [email protected]> wrote:
> >
> >
> >
> >
> >
> > L:, especially the dyad, is so complicated already that it's not worth
> > changing if complex arguments are needed.
> >
> > It would be pretty simple to look through your code for for L:_,
> > wouldn't it? Do you have more than one occurrence? Could you replace
> > the level with a positive constant or a negative constant under the new
> > definition?
> >
> > As you well know, J has a history of making incompatible changes if they
> > are improvements to the language.
> >
> > Henry Rich
> >
> > On 7/28/2018 7:11 PM, Jose Mario Quintana wrote:
> >> I have, at least, produced code which includes L:_1 in a context in
> which
> >> it is not equivalent to &.>.
> >>
> >> Have you considered to get what you want without potentially breaking
> >> existing code (e.g., giving meaning to imaginary whole numbers for the
> >> right argument of L:)?
> >>
> >> (It seems that you wrote L" instead of L: a couple of times in the
> >> description of your proposal.)
> >>
> >> On Fri, Jul 27, 2018 at 3:29 PM, Henry Rich <[email protected]>
> wrote:
> >>
> >>> I think negative level is wrongly defined. (u L:(-r) y) applies u at
> >>> level ((L. y) -r), which measures from the bottom of the tree. What I
> want
> >>> is a form that applies u two levels down, say, which I can't get now.
> I
> >>> propose to change L: to do what I want.
> >>>
> >>> Has anyone found a use for L:(-r) using the current definition?
> >>>
> >>> My proposed change is described at https://code.jsoftware.com/wik
> >>> i/System/Interpreter/Requests#Change_definition_of_negative_
> >>> level_.28strawman.29
> >>>
> >>> Henry Rich
> >>>
> >>> ---
> >>> This email has been checked for viruses by AVG.
> >>> https://www.avg.com
> >>>
> >>> ----------------------------------------------------------------------
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>
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