My understanding is that by using 'cap' you are definitely using a fork, but 'capping' the one end of it!
So whereas (f b g) y would give you something like fy b gy (where b is an infix operator and f and g are unary) then, ([: b g) y would become something like b of gy so you end up with a function composition, as b is rendered unary Hey, I told you my explanations weren't elegant.... Personally I prefer using @ or @: as it maps closer to functional composition. But cap is fine too. On 14 October 2012 02:06, Keith Park <[email protected]> wrote: > Thanks. Cap is sort of what I was looking for. A bit ugly though, but I > suppose it is the price to pay for not having some sort of operator to > deliberately invoke a hook or a fork. > > On Sat, Oct 13, 2012 at 7:57 PM, alexgian <[email protected]> > wrote: > > > I asked this question almost three years ago, when I was first starting. > > Almost the same people answered it, and quite at length, too! > > > > If you want some explanations on the options of composing using the 'cap' > > ([:) or the compose (@) you can look here: > > http://jsoftware.com/pipermail/programming/2010-February/< > > http://jsoftware.com/pipermail/programming/2010-February/018214.html> > > search using "composing without forking (% +/ %)" > > Unfortunately it is not too easy to search old mails. > > > > It is probably also worth understanding the "under" verb, and why > > resistances in parallel are the same concept as "sumation *under* > > inversion" , given by (+/ &.: %) > > > > The differences between @ and @:, and also between &. and &.: have to do > > with rank, I leave their explanation, should you need it, to those more > > elegant than I > > ---------------------------------------------------------------------- > > 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
