[Discussion moved to: programming] Everyone knows (...don't they?) the use of '13 :' to transform a verb from explicit to tacit form, as in:
13 : '(+/y) % #y' +/ % # Novices quickly yearn for '_13 :' to convert the other way, maybe like this? (don't splutter) ... _13 : '+/ % #' (+/y) % #y ...only there isn't just one way of doing it. The result might just as well be: (+/ % #)y viz: simply put '(...)y' round the given tacit verb. Or optionally: 'x(...)y' . Then, treating J as an algebra (and knowing the rules) couldn't the expression then simply be "multiplied out" to any desired level? (I'm being intentionally naive.) Can I propose the word "explicate" for this generalized process? Is "explicate" already in use for something else? Or has (tacit-->explicit) already got a perfectly good name? Art uses the word "un-puzzling". Roger (Stokes) names his proposed verb: "explain". There are in fact a lot of pages in the J wiki on the topic of "explication" if I may call it that. Many seem to have been written in ignorance of the others. It would be good to have a single page, well-signposted for beginners, to pull all these different approaches together. Or even just to list them. Coincidentally I'd already started building just such a roadmap for my own use. Meanwhile I heartily endorse Art's observation: > Newcomers to J should be encouraged very early to use such tools, which supply > multiple avenues to understanding concrete examples. Some of my own recent > puzzlements might not have occurred if I had had a better grounding in the > precise nature of the syntactic features of J. and I like his block-diagram expansion of a given tacit verb. A formidable extension of (5!:4). I also like Roger's approach. Excellent for the raw novice. Though as the novice becomes less raw s/he might soon yearn for something terser. Ideally this would be a collapsed form of the verbose explication, but clearly derived from it. Terse/verbose might be controlled by an optional left arg: 0 or 1. Maybe an intermediate level would be called for. Me, I've had many bites at the "explicate" cherry, but eventually gave up in the face of Ambrus's excellent script: tte.ijs, documented at: http://www.jsoftware.com/jwiki/Scripts/TacitToExplicit This script defines two words: "ttem" (monadic) and "tted" (dyadic). I'd recommend them for close study. I often use "ttem" in practice and think it's the handiest and clearest "explicate" of all. Here's Ambrus's "ttem" in use on a stock example "nub" (m41 -in: Help > Phr > 8A. Numbers & Counting). Note the extreme flexibility: it's written as an adverb, so it can work on a (tacit) verb, not a (string) expression. Nor, for that matter, is it confined to proverbs, unlike 5!:4 . nub=: ((i.@#) = (i.~)) # ] NB. bracketed using 5!:6 to make the process clearer... nub ttem 3 : 0 ]s0=. y i. y ]t0=. (i.@#)y ]r0=. t0 = s0 ]r0 # y ) The prefixes: ] are my own embellishment. They allow you to assign some test data to global: y and then trace the "explication" by re-entering each line in turn. Ian On Mon, Jul 16, 2012 at 3:57 AM, Arthur Anger <[email protected]> wrote: > If you have been puzzled by the result--or non-result--from a published or > personal expression, you may benefit from automated analyses of > parenthesization, syntactic structure, and value production. > > Newcomers to J should be encouraged very early to use such tools, which > supply > multiple avenues to understanding concrete examples. Some of my own recent > puzzlements might not have occurred if I had had a better grounding in the > precise nature of the syntactic features of J. > > Such tools appear in script trace.ijs and the Foreign conjunction 5!:4. > Some > additions to those capabilities are now in script aatrace.ijs, linked via > http://www.jsoftware.com/jwiki/ArtAnger : > > --pyr and parenpyr redisplay a quoted expression with each parenthetical > subgroup raised one line above its context, forming pyramids of various > heights, to improve visual recognition. > > --flowtree produces a "tree" with a downward "flow" of information (data). > It > deviates from simple tree structure when displaying hooks, forks, ties, > adverbs, and most conjunctions, to try to clarify those more complex > processing > paths. When an adverb, rank specifier, or other conjunction controls a > verb's > input and output, that action is suggested by a modified data flow. A Hook, > Fork, Tie, or Bond-repetition is noted explicitly with an H, F, T, or R. > > --flowtree also stores the same expression with inserted calls to a tracing > adverb. Its execution report, of arguments supplied and results produced at > those labeled points, can show very clearly how Insert applies a verb > successively within a list, and how data are passed through the verb phrases > in > a Fork train. > > See the fuller summary at: > http://www.jsoftware.com/jwiki/Essays/Un-puzzling > expressions > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
