All conjunctions including @ bind to their right argument "tightly" meaning just the one token.
The left argument of conjunctions/adverbs is the entire verb phrase to the left of it. myvarp1 uses "linear style" even if it is tacit. `[:` has "no binding" everything to right will execute first, and whatever is to left will wait until that provides a result before the left of [: "composes" with the right. @:, by the way, is more strictly equivalent to [:/"linear style" by ensuring that composition occurs on the full result of the "right expression". (+/@:) will apply to full "result" of the v argument to @: . The sum of the full result requires @: A style that permits shorter parentheses groups with less nesting for conjunctions meant to operate on a long expression to the right, the way @, @: do when "emulating linear style" is to turn the conjunction into an adverb, placing it to the right of the "right expression". so, myvarp3 =: (- +/ % #)(*:@)(+/@:) % # On Sunday, February 12, 2023 at 04:46:35 p.m. EST, More Rice <mrmorer...@gmail.com> wrote: Masters, I understand that there is an excellent reference implementation of varp in addons/stats/base/univariate.ijs to learn from, but I'm trying to do exercises to solidify my understanding of using verb trains/hooks, and the difference when using Atop. I've 2 versions of varp. #1 below is typical of what some of you do (credit: Bob's "Maximum Consecutive 1's in J." Excellent video! Thank you. I wish there were more of these.) - using cap when we want to string monadic verbs sequentially. No problem there. NB. works - using hook/fork/cap myvarp1 =: # %~ [: +/ [: *: (-+/%#) NB. works - using hook/fork/Atop and no cap myvarp2 =: # %~ +/ @ (*: @ (-+/%#)) #2 above, for some reason, I need an extra pair of parentheses to the right of the 1st @ for it to work. I don't get why. For example, the following is broken. NB. It gives me a list instead :( myvarp_broken =: # %~ +/ @ *: @ (-+/%#) Why are they (the missing parentheses w.r.t. #2) needed? thank you Maurice ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
