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 >> >> ---------------------------------------------------------------------- >> 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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
