Meh, no, that won't work. Stick with Jose's version.
(I also don't have the feature enabled which lets me cancel sending an email after "sending" it.) I'll just go do some "practical" work now... Sorry for the noise. -- Raul On 7/6/14, Raul Miller <[email protected]> wrote: > Oops, yes. Sorry about that. > > I should have said: > amend=: (0:{::)`(1:{::)`(2:{::)}~ > > (I'm working right now from a machine where J doesn't run, and I > forget details when I don't test my code.) > > Thanks, > > -- > Raul > > On 7/6/14, Jose Mario Quintana <[email protected]> wrote: >> Raul wrote: >> " >> For example: >> amend=: 0&{::`(1&{::)`(2&{::)} >> amend 0;2 3 5;7#9 >> 9 9 0 0 9 0 9 >> " >> >> Actually, >> >> JVERSION >> Installer: j602a_win.exe >> Engine: j701/2011-01-10/11:25 >> Library: 6.02.023 >> >> amend=: 0&{::`(1&{::)`(2&{::)} >> amend 0;2 3 5;7#9 >> |rank error: amend >> | amend 0;2 3 5;7#9 >> |[-3] >> >> However, >> >> amend=. _: 0&{::@]`(1&{::@])`(2&{::@])} ] >> amend 0;2 3 5;7#9 >> 9 9 0 0 9 0 9 >> >> I use a slight variation of this verb occasionally; yet, I find the forms >> <@:v N} ] and v N} ] extremelly useful for writing tacitly (and I write >> tacitly all the time). >> >> >> >> On Sun, Jul 6, 2014 at 6:42 AM, Raul Miller <[email protected]> >> wrote: >> >>> I would agree that amend is seldom useful in much the same way that >>> computers are seldom useful. That is: it depends on what you mean by >>> "seldom" (and, for that matter, "useful"). >>> >>> Generally speaking, } is one of the less common characters that I use >>> when I write in J, but I do use it. >>> >>> Also, in addition to the very fine 0:`[`]} which behaves something like >>> this: >>> >>> 2 3 5 0:`[`]} 7#9 >>> 9 9 0 0 9 0 9 >>> >>> (Aside: note that in the above expression 2 3 5 is a word, and 0: is a >>> separate word. Try ;:'2 3 5 0:`[`]} 7#9' if you want proof.) >>> >>> ... in addition to that approach, you can also arrange so that all >>> arguments are given in an argument list, if you use >>> 0&{::`(1&{::)`(2&{::)} >>> >>> For example: >>> amend=: 0&{::`(1&{::)`(2&{::)} >>> amend 0;2 3 5;7#9 >>> 9 9 0 0 9 0 9 >>> >>> But, as with everything, whether this is a good thing or not depends >>> on what you are trying to do... >>> >>> Which leads back to the question: what are you trying to do? >>> >>> Thanks, >>> >>> -- >>> Raul >>> >>> On 7/6/14, Ric Sherlock <[email protected]> wrote: >>> > I don't agree that Amend is seldom useful. I do agree that it isn't >>> > the >>> > easiest thing to get your head around (perhaps why you have found >>> > other >>> > ways to getting stuff done). >>> > >>> > Aai has shown how to tacitly use Amend so it seems that 13 : is not >>> > smart >>> > enough to give you a tacit equivalent. I suspect the reason Amend has >>> been >>> > defined as an adverb is that it requires 3 arguments: the array to >>> > amend, >>> > the indicies to amend, the replacement data. Compare that to From >>> > which >>> > only requires 2 bits of info (the array, the indicies). >>> > >>> > >>> > >>> > On Sun, Jul 6, 2014 at 7:53 PM, Ian Clark <[email protected]> >>> > wrote: >>> > >>> >> I think Erling is quite right, if you take what he says literally: >>> "Amend >>> >> is seldom useful for indexed replacement when you write tacit J". >>> >> >>> >> I'd go further and say "Amend is seldom useful." Period. I write a >>> >> lot >>> of >>> >> J >>> >> code and I hardly ever use it. >>> >> >>> >> To someone coming from C (say), this cries out for explanation. In C, >>> just >>> >> about everything is done by keyhole surgery, i.e. by tinkering with >>> >> whatever happens to be at the end of a pointer (read: index). In J, >>> >> just >>> >> about nothing is done that way. >>> >> >>> >> Let me give an example. Suppose I want to write a verb to zero the >>> >> x'th >>> >> element of a list y ... >>> >> I can easily write it as an explicit verb: >>> >> >>> >> zero=: 4 : '0 x} y' >>> >> 3 zero i.6 >>> >> 0 1 2 0 4 5 >>> >> >>> >> But "13 :" refuses to give me an equivalent tacit verb ... >>> >> >>> >> 13 : '0 x}y' >>> >> 4 : '0 x}y' >>> >> >>> >> Is this just a shortcoming of "13 :" ? Does anyone know a "nice" >>> >> tacit >>> >> equivalent? I don't. >>> >> >>> >> Contrast this with what happens if I switch round 0 and x (...which >>> gives >>> >> me a verb to replace the first element of a list y with x). In this >>> >> case >>> >> "13 :" does deliver me a nice simple tacit equivalent ... >>> >> >>> >> 13 : 'x 0}y' >>> >> 0} >>> >> >>> >> So why doesn't 13 : '0 x}y' do something equally as nice? It's all >>> >> explained in http://www.jsoftware.com/jwiki/Vocabulary/curlyrt#dyadic >>> >> . >>> >> But >>> >> that doesn't really explain to a newcomer why Amend was designed as >>> >> an >>> >> adverb: >>> >> x m} y >>> >> with (index) m as an *operand*, not an *argument*. >>> >> >>> >> Yes, I can write a tacit verb to zero the x'th element of list y ... >>> >> >>> >> zero2=: 13 : 'y * y~:x' >>> >> 3 zero2 i.6 >>> >> 0 1 2 0 4 5 >>> >> zero2 >>> >> ] * ~: >>> >> >>> >> ... but not by using Amend, which is quite simply not useful in that >>> role. >>> >> Though I'm not claiming it can't be done - in fact there's a worked >>> >> example >>> >> in: http://www.jsoftware.com/jwiki/Vocabulary/curlyrt#dyadic under >>> "More >>> >> Information". But I wouldn't call it "nice". >>> >> >>> >> This illustrates the J approach to programming: >>> >> http://www.jsoftware.com/jwiki/Vocabulary/Loopless -and how it >>> contrasts >>> >> with the C approach. Henry would explain it far better than I can, >>> >> but >>> >> he's >>> >> busy. >>> >> >>> >> IanClark >>> >> >>> >> >>> >> On Sat, Jul 5, 2014 at 8:59 PM, Erling Hellenäs < >>> [email protected]> >>> >> wrote: >>> >> >>> >> > Hi all ! >>> >> > >>> >> > When you write tacit code, the index m used by Amend, syntax >>> description >>> >> > x m} y, is a constant? >>> >> > Normally you have a variable you want to use for indexing? This >>> >> > means >>> >> > Amend is seldom useful for indexed replacement when you write tacit >>> >> > J? >>> >> > Are there any descriptions of nice ways to do indexed replacement >>> >> > in >>> >> tacit >>> >> > J? >>> >> > As with Amend, the result has to be a new variable, of course. >>> >> > >>> >> > Cheers, >>> >> > >>> >> > Erling Hellenäs >>> >> > >>> >> > ---------------------------------------------------------------------- >>> >> > 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
