> In other words, I got to J the same way Arthur Rubinstein directed the > tourist to Carnegie Hall.
I didn't know this, and had to google it. Here it is, for any other ignoramus on this list ... http://quotationsbook.com/quote/31803/ Apparently, he was approached in the street near the Carnegie Hall in NY by a man who asked, "Pardon me sir, how do I get to Carnegie Hall?“; to which he replied, "Practice, practice, practice!”. On Thu, Nov 29, 2012 at 10:15 PM, Dan Bron <j...@bron.us> wrote: > I can't disagree with your contention about how people (try to) approach J or > other programming languages. > > For my part, when I started J, I found the DoJ impenetrable and eschewed it > for the first year or two of my career. I learned J through the collective > wisdom and generosity of these Forums, combined with innumerable > conversations (ok: arguments) with the interpreter. Once I already knew J, > the DoJ became valuable (in fact, invaluable). > > In other words, I got to J the same way Arthur Rubinstein directed the > tourist to Carnegie Hall. And, as far as I know, there is no other way to get > there. > > -Dan > > PS: I'm not trying to be glib. Like any project, our documentation can > always be improved and never be "finished". And over the years many > intelligent, generous people have expanded and contributed to it in many > different voices, media, styles, and methods. And I'm sure that will > continue. > > But I'm equally sure there is no silver bullet (which is the flip side of > "our documentation can never be finished"). Ultimately, it comes down to the > individual aspirant. > > > -----Original Message----- > From: programming-boun...@forums.jsoftware.com > [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Ian Clark > Sent: Thursday, November 29, 2012 3:16 PM > To: programm...@jsoftware.com > Subject: Re: [Jprogramming] @: and capped fork > >> What provoked your doubt? > > In learning J, I've stumbled from one false assumption to another. > Mainly about verb composition. Were I to be the only person to experience > this, it could be put down to a weak intellect. But if my experience is not > uncommon, it points to a need for J documentation to be better. > > Just today, whilst testing an explication utility I have on the chocks, I > thought I'd stumbled on yet another unwarranted assumption I'd been making in > the code. It was one I could not easily check from the standard reference > material. To be sure I needed to ask on the forum. > > The problem with J documentation as it's structured, is that to compose 2 > verbs you naturally think of a conjunction -- and J has a wealth of those. > Far more than APL. If you want to choose a suitable conjunction you can read > its description in Voc. But hooks and forks, especially Capped Fork, compose > verbs too, yet they're not documented in a comparable way. You have to be > au-fait with the Dic chapter on Trains, or Chapter 40 of JforC. > > It's my contention that experienced programmers learn a new language by > reading the reference manual as they go along, one feature at a time. They > don't digest an armful of primers or textbooks up-front, no matter how > exciting and readable. Learning J, that approach just happens to induce a > blind spot over Capped Fork -- and verb-trains in general. > > Ian > > On Thu, Nov 29, 2012 at 5:44 PM, Dan Bron <j...@bron.us> wrote: >> Right. For this reason (or similar ones, like when g is a train), I >> phrase the identity as ([: f g) ↔ f@:(g) . >> >> As to where this is stated: well, it's recorded informally in >> innumerable documents and J learning materials. If you're looking for >> formal guarantees in canonical material (the DoJ), you'll have to >> arrive at the equivalence through a chain of logic. >> >> First, we have the the definition of capped fork in §II.F, following >> the definition of non-capped fork [1]: >> >> (A) "If f is a cap ([:) the capped branch simplifies the forks to >> i. g h y and >> ii. g x h y" >> (B) "The ranks of the hook and fork are infinite." >> >> Then, we have the definition of @: in the vocabulary [2]: >> >> (C) "@: is equivalent to @ except that ranks are infinite." >> >> Which refers back to the definition of @, which is given in the >> Vocabulary as [3]: >> >> (D) " u@v y ↔ u v y" >> (E) "x u@v y ↔ u x v y . >> >> So, after adjusting for the different names given to the verbs, we the >> following correspondences: >> >> (Ai) "([: f g) y ↔ g h y" vs (D) "f@g y ↔ f g y" >> (Aii) "x ([: f g) y ↔ g x h y" vs (E) "x f@g y ↔ u f g y" >> >> (B) "The ranks of the hook and fork are infinite" vs >> (C) "@: is equivalent to @ except that ranks are infinite." >> >> Which, as far as I can tell, establishes the identity ([: f g) ↔ f@:g >> (provided we heed the advice given in latter's definition, i.e. >> "because a conjunction applies to the entity immediately to its right, >> expressions to the right of conjunctions commonly require >> parenthesization.") >> >> What provoked your doubt? >> >> -Dan >> >> [1] §II.F, definition of trains >> http://www.jsoftware.com/help/dictionary/dictf.htm >> >> [2] Vocabulary entry for @: >> http://www.jsoftware.com/help/dictionary/d622.htm >> >> [3] Vocabulary entry for @ >> http://www.jsoftware.com/help/dictionary/d620.htm >> >> -----Original Message----- >> From: programming-boun...@forums.jsoftware.com [mailto:programming- >> boun...@forums.jsoftware.com] On Behalf Of bob therriault >> Sent: Thursday, November 29, 2012 12:00 PM >> To: programm...@jsoftware.com >> Subject: Re: [Jprogramming] @: and capped fork >> >> HI Ian, >> >> If your v includes an adverb such as / the long left reach of >> conjunctions could get you into trouble. That would be part of the >> parsing rules for verbs vs conjunctions. >> >> (+:@:+/) 3 4 5 >> 42 >> ([:+:+/) 3 4 5 >> 24 >> >> Cheers, bob >> >> On 2012-11-29, at 8:49 AM, Ian Clark wrote: >> >>> Department of Sudden Doubts... >>> >>> If u and v are verbs, do (u@:v) and ([: u v) really behave the same >>> under all circumstances? >>> >>> If so, where would I go to find this fact written up? >>> --------------------------------------------------------------------- >>> - 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 > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
