Jürgen, Actually '&' is a dyadic operator:
x u&v y <-> (v x) u v y It's also the currying operator when applied to a function and data (keep in mind there is no strand notation in J): u&y x <-> x u y <-> x&u y The error is because & is being fed two numbers, when it can only digest one non-function argument at most. Makes J look excessively complicated doesn't it :) One does tend to get used to and appreciate it though. The choice of primitives (and, surprisingly enough, their very mnemonic ASCII symbols) was particularly well done. Logical 'and' is written '*.' and works like APL's dyadically. Monadically, it yields a pair of a number's magnitude and complex angle (in ]-pi,pi]), and this for each scalar of an array, thus adding a trailing dimension to it. A cool usage example is sorting a complex vector by angle, then length (useful for calculating a convex hull among other things): /:~ &.: (|. @ *.) v /:~ is sort, |. is reverse, *. is length/angle, @ is function composition, and &.: is an operator 'under' which applies the right function, then the left, then undoes the right one (applies its inverse, if applicable). I do find such operations on complex data easier with primitives like this than having to use a dyadic circular function (whose left arg I always have to look up). I guess both languages have their quirks :) Cheers, and keep up the good work Jürgen; I second Peter's praise! Louis On 27 Apr 2017, at 21:01, Juergen Sauermann <juergen.sauerm...@t-online.de> wrote: > Hi Louis, > > I am not at all a J programmer, but I remember that in old APL the 'and' was > purely boolean (giving > a domain error as well if the arguments were not 0 or 1), but the ISO > standard for extended APL then > allowed non-boolean arguments as well (and the result is then the least > common multiple (aka. LCM) > of the arguments). > > I suppose that J is still behaving like the old APL for dyadic &. No idea, > though what monadic & does in J, it seems > to have a meaning there? Or was it the !!! that cause the error? One more > reason to use APL. > > /// Jürgen > > >> On 04/27/2017 07:49 PM, Louis de Forcrand wrote: >> Jürgen, >> >> At first I thought I had been doing it wrong all these years, and that now I >> finally had seen the light, but in J: >> >> 1, 2, 3 & 4!!! >> |domain error >> | 1,2, 3&4!!! >> 1, 2, 3, & 4!!! >> 1 , 2 , 3 ,&4 ! ! ! >> >> What are we going to do??? >> >> Louis >> >> On 27 Apr 2017, at 13:44, Juergen Sauermann <juergen.sauerm...@t-online.de> >> wrote: >> >>> Hi, >>> >>> the Oxford Comma is definitely broken because 'and' is dyadic: >>> >>> 1, 2, 3, ∧ 4 >>> VALENCE ERROR >>> 1,2,3,∧4 >>> ^ >>> >>> 1, 2, 3 ∧ 4 >>> 1 2 12 >>> >>> >>> /// Jürgen >>> >>> >>>> On 04/26/2017 04:29 PM, enz...@gmx.com wrote: >>>> http://www.theonion.com/americanvoices/oxford-comma-wins-court-case-workers-55578 >>>> >>>> >>>> On Sat, 22 Apr 2017 16:25:52 +0200 >>>> Juergen Sauermann <juergen.sauerm...@t-online.de> wrote: >>>> >>>>> Hi, >>>>> >>>>> this sentence is the verbatim copy of the phrase proposed in >>>>> https://www.gnu.org/licenses/gpl.txt >>>>> (chapter 17) and I do not feel like criticising the GNU project for >>>>> their spelling. >>>>> >>>>> /// Jürgen >>>>> >>>>> >>>>> On 04/22/2017 12:28 AM, enz...@gmx.com wrote: >>>>> >>>>> >>>>> Thanks you guys doing this )help is really appreciated - maybe I can >>>>> make a contribution too >>>>> >>>>> line 13 but WITHOUT ANY WARRANTY; without even the implied >>>>> warranty of ; -> , for oxford comma? >>>>> >>>>> references : >>>>> >>>>> https://www.grammarly.com/blog/what-is-the-oxford-comma-and-why-do-people-care-so-much-about-it/ >>>>> >>>>> http://www.necn.com/news/new-england/Missing-Comma-Could-Cost-Maine-Company-Millions-416458593.html >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> On Fri, 21 Apr 2017 23:01:01 +0200 >>>>> Alexey Veretennikov <alexey.veretenni...@gmail.com> wrote: >>>>> >>>>> Hi, >>>>> >>>>> Sure here it is. Don't expect anything big in it - it is just a couple >>>>> of lines of text. >>>>> >>>>> >>>>> >>>>> >
