Exactly, when [: appears as the first component of a fork it triggers a modification in the way the middle verb normally takes its arguments and, at least in my mind, that makes [: 'non-functional.' However, that is besides the point that I was really trying to make early in this thread: the implementation of [:, I believe, did not require any change to the parsing rules but a modification to the previous way that the fork was executed by means of "an extra rule that has to be explicitly coded into the interpreter" as you Viktor well put it (and apparently with negligible adverse effect on performance). Would a similar approach work to implement Neville's ideas? If so, could it be done efficiently? Is it necessary to implement Neville's [. and ]. to code tacitly in practice? My personal opinion on the latter is that it in not necessary and even if they were ever implemented I would probably avoid them (just as I avoid [:); unlike Neville and his students, some of us routinely generate tacit verbs to implement computing projects at my company (the implementation of all of our critical projects is done in this manner). Yet, as always, I could change my mind eventually.
________________________________ From: Viktor Cerovski <[email protected]> To: [email protected] Sent: Thursday, July 30, 2009 8:22:51 PM Subject: Re: [Jprogramming] Third argument Raul Miller-4 wrote: > > [...] > > Consider [: % *: > > Before the introduction of cap's special treatment during parsing, the > TRIDENT parsing handler would have formed a fork from these three verbs. > > [: has no side effect -- in fact it never does anything -- and in this > context, it is nothing but information. > [...] > [: does produce domain error when invoked either monadically or dyadically. If x (u v w) y were defined to be (x u y) v (x w y) for any three verbs u v w, it would have produced the error when u is [:. So, the definition of [: u v is an extra rule that has to be explicitly coded into the interpreter. -- View this message in context: http://www.nabble.com/Re%3A-Third-argument-tp24656753s24193p24749322.html Sent from the J Programming mailing list archive at Nabble.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
