erb( and so usable in tacit expressions):
>
> itmemamend =: 4 : 'x}y'
>
> there are also enhancement as to rank that can replace the simpler case
> above:
>
> itemamend2 =: (([: ;/(,.i.@#))@:[ { ])"1 _
> itemamend =: 4 : '((2}.$y) $"1 0 x)} y'
>
>
&
But the code you gave doesn't perform an in-place amend with J's current
implementation. Compare:
a=.?~1e7
6!:2 'a =. 2 (9}) a'
1.6e_5
6!:2 '?~1e7'
2.71278
6!:2 '2&(9})^:100 ?~1e7'
10.6457
Of course it's possible for J to do an in-place amend in this situation,
as J's arrays a
I think you can use a gerund for more dynamic amend source subset and
replacement parts like with the power verb or insert. I am looking for an
opportunity to refactor or factor in gerund usage to everything I write as
gerunds are obviously the proper way to write in j after you get your head
aroun
Actually, there's no problem with doing an in-place amend in tacit
code. For example:
2 (9}) ?~1e7
If something goes wrong, you have trashed the right argument being
passed in to the tacit amend, but it wasn't stored anywhere else so it
would have been lost anyways.
The problem occurs wh
e simpler case above:
itemamend2 =: (([: ;/(,.i.@#))@:[ { ])"1 _
itemamend =: 4 : '((2}.$y) $"1 0 x)} y'
- Original Message -
From: Jose Mario Quintana
To: Programming forum
Cc:
Sent: Tuesday, July 22, 2014 12:39:33 PM
Subject: Re: [Jprogramming] Tacit J and indexed repl
Don wrote:
"I think it would be impossible to do an amendment in place in tacit code"
It is not possible to amend in place tacitly in the official version of J.
However, tacit versions of amend, and append, in-place have been
implemented in an special version of J. These are definitively not for
Erling wrote:
"I can't follow and it seems I might be misinterpreted."
No worries, all I was (am) saying, or trying to say, was that I am not done
yet discussing the topics raised in this thread; often I disengage from the
forums for extended periods for one reason or another, and last time was
fo
I can't follow and it seems I might be misinterpreted. /Erling
On 2014-07-20 23:04, Jose Mario Quintana wrote:
I was on vacation eating and drinking at street side stands in Mexico City
and sun bathing on the Mayan Riviera. I am sorry. Nah, I am not.
On Sun, Jul 20, 2014 at 3:59 PM, Erling H
I was on vacation eating and drinking at street side stands in Mexico City
and sun bathing on the Mayan Riviera. I am sorry. Nah, I am not.
On Sun, Jul 20, 2014 at 3:59 PM, Erling Hellenäs
wrote:
> Didn't we finish this thread? How about a new thread, possibly with
> summaries from earlier di
Didn't we finish this thread? How about a new thread, possibly with
summaries from earlier discussions? This thread was only about indexed
replacement and Amend? /Erling
On 2014-07-20 21:17, Jose Mario Quintana wrote:
"It's déjà vu all over again." :)
(
http://www.jsoftware.com/pipermail/pr
"It's déjà vu all over again." :)
(
http://www.jsoftware.com/pipermail/programming/2009-December/017478.html
http://www.jsoftware.com/pipermail/programming/2009-December/017480.html
http://www.jsoftware.com/pipermail/programming/2009-December/017482.html
)
On Tue, Jul 8, 2014 at 7:05 PM, Erling
> > > the very definition and purpose of Amend.
> > > > > > >
> > > > > > > In general, using Amend to construct an array for the first
> time
> > > > seems
> > > > > > fine
> > > > > > > to me.
t; > seems
> > > > > fine
> > > > > > to me. What I'd be more wary of is if you notice yourself using
> > for
> > > > > > intermediate transformations - particularly if the changes (the
> > uses
> > > of
> > &g
u notice yourself using
> for
> > > > > intermediate transformations - particularly if the changes (the
> uses
> > of
> > > > })
> > > > > are both frequent and small, because that's indicative of the
> "scalar
> > > > >
gt; > I'd further say that if you're confident in your use of J and
> > > > array-oriented programming, there's no particular reason to *avoid*
> > > amend.
> > > > I think you'll just naturally find yourself using it less. But in
> the
> > > > c
nd.
> > > I think you'll just naturally find yourself using it less. But in the
> > > cases where it's the right tool for the job - well, then, it's the
> right
> > > tool for the job. I'd use it with no more compunction than I'd have
> > about
&
s the right tool for the job - well, then, it's the right
> > tool for the job. I'd use it with no more compunction than I'd have
> about
> > # or /. or + or whatever. (But that's because I'm an egomaniac, and I'm
> > pretty
bout
> # or /. or + or whatever. (But that's because I'm an egomaniac, and I'm
> pretty sure of my ability to discriminate the situations } is the right
> tool for the job, and when I'm using it as a crutch.)
>
> -Dan
>
> - Original Message
tions } is the right
tool for the job, and when I'm using it as a crutch.)
-Dan
- Original Message ---
Subject: Re: [Jprogramming] Tacit J and indexed replacement
From: Ben Gorte - CITG
Date: Thu, 10 Jul 2014 14:43:01 +
To: "programm...@jsoftware.com&q
gt;>N =: v (;/i) } 1000 1000$0
>>
>> And of course:
>>N -: M
>> 1
>>
>> Is there a better way to do this?
>>
>> Ben
>> ___
>> From: programming-boun...@forums.jsoftware.com
>> [programming-boun...@forums.jso
> [programming-boun...@forums.jsoftware.com] on behalf of Dan Bron
> [j...@bron.us]
> Sent: Tuesday, July 08, 2014 02:23
> To: programm...@jsoftware.com
> Subject: Re: [Jprogramming] Tacit J and indexed replacement
>
> Do you have examples, in practice, where you've wanted
>
> Ben
> ___
> From: programming-boun...@forums.jsoftware.com
> [programming-boun...@forums.jsoftware.com] on behalf of Dan Bron
> [j...@bron.us]
> Sent: Tuesday, July 08, 2014 02:23
> To: programm...@jsoftware.com
> Subject: Re: [Jprogramming] Taci
[programming-boun...@forums.jsoftware.com] on behalf of Dan Bron [j...@bron.us]
Sent: Tuesday, July 08, 2014 02:23
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Tacit J and indexed replacement
Do you have examples, in practice, where you've wanted to modify one item (or a
sublist) f
Dan wrote:
>My contention (and I think Ian and Henry's, though I don't want to put
>words in their mouths) is that J encourages holistic (i.e. all-at-once)
>thinking, which makes the use of } much rarer in J than one would expect
>coming from other languages.
Yes, I'd go along with that. Splitting
: [Jprogramming] Tacit J and indexed replacement
@Linda - the "domain error" is because you've defined h as:
h=: 3 :'0 x } y'
That should have been
h=: 4 :'0 x } y'
if you're going to call h dyadically.
But I sympathize. Exactly this error catches me out all too ofte
al Message ---
Subject: Re: [Jprogramming] Tacit J and indexed replacement
From: Jose Mario Quintana
Date: Tue, 8 Jul 2014 18:10:27 -0400
To: Programming forum
Dan, ultimately, I find difficult to agree, or disagree, with the statement:
"
x m} y is used in J much less than
One thing I find fascinating with J is that it forces you to put the
operations in logical order. At least that's how I feel. If I have three
pieces of information to do something with I think a little more, do
something with two pieces, then use the result to include another piece.
When I firs
Dan wrote:
> I rarely find a call for } . I'm wondering if you've
> [Pepe] have invented or discovered generally beneficial
> uses of } unrelated to performance.
Pascal responded:
> I think } (dyadic amend) is pretty essential.
> The obvious use is amending one (or sublist) item
>
J avoids a pitfall in scalar language amend by replacement. It verifies
that the replacement won't crash half-way through leaving the data
corrupted. It is transparent to the program whether the amend amends in
place or not, other than performance. And sometimes amend makes more sense
than other wa
In most languages indexed replacement is indexed replacement? In J and
in most functional languages it is not? You get a brand new variable?
So, why give the user the flawed impression he can still do indexed
replacement and do amendments to variables/nouns? And at the same time
in tacit code w
I think it would be impossible to do an amendment in place in tacit code,
but amendment should still work in a tacit expression, just not in place.
But if the result were assigned back to the original variable what will
happen? Would the tacit expression prevent it from recognizing the
operation as
Erling wrote: "It's obviously not possible to do any amendments in tacit
code?" Adding after wards: "A principle of functional programming is you
never modify a variable?"
From my perspective those (rhetorical?) questions are separate. Regarding
the first question, consider the verb (v) that p
certainly (especially in my "professional J-ing" days)
> see the benefit of } for performance. But I'm wondering if you've
> invented or discovered generally beneficial uses of } unrelated to
> performance. I'd be very interested in that, if so ('cause the only on
end.
On Tue, Jul 8, 2014 at 1:22 PM, Linda Alvord
wrote:
> I'm comparing it to the post below it that says it is a verb. It struck
> me as a peculiar inconsistency.''
>
> Linda
>
> -Original Message-
> From: programming-boun...@forums.jsoftware.com [mailto:
&
: programm...@jsoftware.com
Subject: Re: [Jprogramming] Tacit J and indexed replacement
I think we have covered these issues with you before. Do you remember
why you should get that error?
Thanks,
--
Raul
On 7/8/14, Linda Alvord wrote:
> And then!
>
> h=: 3 :'0 x } y'
>
July 08, 2014 5:52 AM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Tacit J and indexed replacement
I think we have covered these issues with you before. Do you remember
why you should get that error?
Thanks,
--
Raul
On 7/8/14, Linda Alvord wrote:
> And then!
>
> h=: 3 :&
om: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On BehalSSf Of Linda Alvord
Sent: Tuesday, July 08, 2014 5:14 AM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Tacit J and indexed replacement
Ian's post was very early in this threa
;
> -Original Message-
> From: programming-boun...@forums.jsoftware.com
> [mailto:programming-boun...@forums.jsoftware.com] On BehalSSf Of Linda
> Alvord
> Sent: Tuesday, July 08, 2014 5:14 AM
> To: programm...@jsoftware.com
> Subject: Re: [Jprogramming] Tacit J and indexed rep
: programm...@jsoftware.com
Subject: Re: [Jprogramming] Tacit J and indexed replacement
Ian's post was very early in this thread, but something has puzzled me for a
while as I tried to write a tacit version:
f=: 13 :'0 x } y'
4 5 f i.11
0 1 2 3 0 0 6 7 8 9 10
g=: 4 :'0 x
g
4 : '0 x } y'
4!:0 <'f'
3
4!:0 <'g'
3
Linda
-Original Message-
From: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Ian Clark
Sent: Sunday, July 06, 2014 3:54 AM
To: pr
ramming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Marshall Lochbaum
Sent: Monday, July 07, 2014 11:07 PM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Tacit J and indexed replacement
Dan didn't really give you the whole story (well, I
Dan didn't really give you the whole story (well, I won't either, I
suppose), so I'll discuss this a bit more.
An array in J (which refers to a multidimensional array, rather than
just a list) consists of a shape given by $ and a ravel given by , . The
entire ravel is stored contiguously in memory
hough it can generally be achieved with a gerund version of })
> that provides verb based amend.
>
> amend_z_ =: 2 : 0
> s=. v"_ y
> (u (s{y)) (s}) y
> :
> s=. v"_ y
> (x u (s{y)) (s}) y
> )
>
>
> - Original Message -
> From: Dan Bron
> To: &
23:54 PM
Subject: Re: [Jprogramming] Tacit J and indexed replacement
Do you have examples, in practice, where you've wanted to modify one item (or a
sublist) from a data structure?
Would you say those circumstances are the exception or the rule? (I'm asking
because it's definitely the excep
> From: Dan Bron
> To: programm...@jsoftware.com
> Cc:
> Sent: Monday, July 7, 2014 7:42:35 PM
> Subject: Re: [Jprogramming] Tacit J and indexed replacement
>
> Pepe, I'm with Ian and Henry on this one: questions of efficiency aside, I
> rarely find a call for } . The only
lementing the
example in this thread.
- Original Message -
From: Dan Bron
To: programm...@jsoftware.com
Cc:
Sent: Monday, July 7, 2014 7:42:35 PM
Subject: Re: [Jprogramming] Tacit J and indexed replacement
Pepe, I'm with Ian and Henry on this one: questions of efficiency aside,
The answer to all three of your questions, in the current implementation of J,
is "yes" (where a "generalized array" corresponds to J's "boxed array").
But bear in mind that J is an abstract language, a notation independent of any
implementation, and so future implementations may make choices w
A generalized array is only an array of links to arrays? When you
allocate a new generalized array, the arrays it links to can remain?
When you assign a new array in a cell of your generalized array, all you
have to do is set a link to the array assigned to the cell? /Erling
On 2014-07-08 01:1
d, scalar substitution).
-Dan
- Original Message ---
Subject: Re: [Jprogramming] Tacit J and indexed replacement
From: Jose Mario Quintana
Date: Mon, 7 Jul 2014 19:12:55 -0400
To: Programming forum
Ian wrote:
"
And the reason for that has less to do with finding it
6 17 8
>Date: Mon, 07 Jul 2014 20:46:32 +0200
>From: Erling Hellen?s
>To: programm...@jsoftware.com
>Subject: Re: [Jprogramming] Tacit J and indexed replacement
>Message-ID: <53baeb08.3070...@erlinghellenas.se>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Ian wrote:
"
And the reason for that has less to do with finding it "hard to get my head
round Amend" than the fact that "in-place array modification" is a
technique that goes hand-in-hand with a scalar approach to problem-solving,
which is not what J is designed to do well.
"
How come? In the fo
J is not a pure functional language. But tacit J is a (n almost) purely
functional subset of J (exceptions include things like ? and s:, but much more
importantly !:).
In particular, tacit J /has no variables/. You can't, in any way, modify a
previous result, because you have no way to refer to
Yes, what I said is it seems like a misnomer. Functional J has
variables, but they are handled by the interpreter? Still they are never
changed? This could create a performance problem if you do a lot of
small changes to big data structures? It is essential to handle this
efficiently? Still J d
What variable? Tacit programming does not refer to any arguments
explicitly; or, are you saying that “amend” is a misnomer (if so, that is
not my domain)?
On Mon, Jul 7, 2014 at 6:07 PM, Erling Hellenäs
wrote:
> A principle of functional programming is you never modify a variable? What
> Amend
A principle of functional programming is you never modify a variable?
What Amend does is create a new variable from other existing variables?
Nothing is amended? /Erling
On 2014-07-07 23:50, Jose Mario Quintana wrote:
Erling wrote:
"
It's obviously not possible to do any amendments in tacit co
R.E. wrote:
> 2 2 3
Linda wrote:
> 123 123 2 3
>2 2 2
R.E. Boss' original example:
http://jsoftware.com/help/dictionary/d530v.htm
[2] In f} y , f addresses the indices of the _ravel_ of y,
even though the Vocabulary doesn't say that:
http://www.jsoftware.com/pipe
Erling wrote:
"
It's obviously not possible to do any amendments in tacit code? It is also
less elegant to pass these three parameters in the two arguments in tacit
code?
"
Well, Raul and I showed general verbs to perform amendments tacitly. Once
I was as puzzled as you are (were?) but I found en
Erling Hellenäs wrote:
> q([ } ])x,:y
This doesn't do what you expect because } isn't what you think it is.
Unlike (for example) { which is a verb, } is an adverb: a completely
different kind of animal, with completely different rules. That's why
you're having trouble using it tacitly. Using
Hi all !
Just to clarify one thing:
q } x,:y
0 11 2
13 4 15
6 17 8
q([ } ])x,:y
0 1 2
3 4 5
6 7 8
10 11 12
13 14 15
16 17 18
q ([ {"0 1 ] ) x,"0 y
0 11 2
13 4 15
6 17 8
Why is Amend so much faster then From? It seems to do the same thing?
/Erling
On 2014-07-07 22:19, Dan Bron
Odd:
1 mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Erling
Hellenäs
Sent: Monday, July 07, 2014 2:47 PM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Tacit J and indexed replacement
An example:
x=:3 3 $i.9
y=:x+10
q=:2|x
x
0 1 2
3 4 5
6 7 8
y
10 11 12
13
I wrote:
> If you want to be able to calculate q on-the-fly, using tacit code,
> here's a little helper utility:
> ...
> It works on the same principles as x q} y , using gerund} to permit
> the calculation of q from x and/or y at runtime. It's a bit convoluted
> because the definition
I wrote:
> mergeMask =: (&>) / (`>) } (@:,) (&<)
In retrospect, given that x and y will by definition agree in type and
shape, we can skip the boxing and simplify mergeMask:
mergeMask =: / (`]) } (@:,:)
x (2|[) mergeMask y
0 11 2
13 4 15
ger said:
"The pattern is that the monadic case of gerund op
uses the monadic meaning of op while the dyadic case
uses the dyadic meaning.
In the case of gerund} , the dyadic case IS allowed,
but it is invoked via x gerund}y ."
http://www.jsoftware.
An example:
x=:3 3 $i.9
y=:x+10
q=:2|x
x
0 1 2
3 4 5
6 7 8
y
10 11 12
13 14 15
16 17 18
q
0 1 0
1 0 1
0 1 0
q {"0 1 x,"0 y
0 11 2
13 4 15
6 17 8
/Erling
On 2014-07-07 19:53, Erling Hellenäs wrote:
It's obviously not possible to do any amendments in tacit code? It is
also le
> >
> >
> >R.E. Boss
> >
> >(Add your info to http://www.jsoftware.com/jwiki/Community/Demographics )
> >
> >
> >
> >>-Original Message-
> >>From: programming-boun...@forums.jsoftware.com [mailto:programming-
> >>boun...@forums
its equivalent to 1 2 3 < 2 2 2
1 2 3,:2 2 2
creates 2 items (each item a list)
- Original Message -
From: Erling Hellenäs
To: programm...@jsoftware.com
Cc:
Sent: Monday, July 7, 2014 2:05:03 PM
Subject: Re: [Jprogramming] Tacit J and indexed replacement
This one beats me. look
14 1:53:52 PM
Subject: Re: [Jprogramming] Tacit J and indexed replacement
It's obviously not possible to do any amendments in tacit code? It is
also less elegant to pass these three parameters in the two arguments in
tacit code? Any opinions about the use of From to do the same thing?
4 12:33
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Tacit J and indexed replacement
Another approach for this is:
(x*-.q)+y*q
Sadly, that only works when x and y are numeric. Boxes and literals do
not have zero and 1 values (hypothetically "fill" could be zero, but
"1&
It's obviously not possible to do any amendments in tacit code? It is
also less elegant to pass these three parameters in the two arguments in
tacit code? Any opinions about the use of From to do the same thing?
NB. x and y are arrays of the same rank
NB. q is a boolean, also of this rank
NB. T
REB wrote:
> 2 2 3
Wow. That's going right into PrimitivePrimitives!
max =. .) (100 100 ?@$ 0)
1
-Dan
--
For information about J forums see http://www.jsoftware.com/forums.htm
4 12:33
> To: programm...@jsoftware.com
> Subject: Re: [Jprogramming] Tacit J and indexed replacement
>
> Another approach for this is:
>(x*-.q)+y*q
>
> Sadly, that only works when x and y are numeric. Boxes and literals do
> not have zero and 1 values (hypothetically "fill
Another approach for this is:
(x*-.q)+y*q
Sadly, that only works when x and y are numeric. Boxes and literals do
not have zero and 1 values (hypothetically "fill" could be zero, but
"1" is harder to rationalize.)
A variant which uses amend might be:
(q#y) (I.q)} x
This only works when x an
Hi all !
About the problem I want to solve.
Generally you compare some arrays and you want to replace part of one of
them with info from the other or from some other array of the same
dimensions?
I found a solution not using Amend:
NB. x and y are arrays of the same rank
NB. q is a boolean
Subject: Re: [Jprogramming] Tacit J and indexed replacement
Thanks, guys, keep the ideas coming. There's enough been said in this
thread to enable me to substantially improve the NuVoc presentation of
Amend in http://www.jsoftware.com/jwiki/Vocabulary/curlyrt#dyadic - which I
think most would
Thanks, guys, keep the ideas coming. There's enough been said in this
thread to enable me to substantially improve the NuVoc presentation of
Amend in http://www.jsoftware.com/jwiki/Vocabulary/curlyrt#dyadic - which I
think most would agree doesn't present Amend in the most appealing light.
Perhaps
Since it'w nagging at me (and this is still unteted code :/), here's
what I currently think i should have said:
amend=: (0:{::])`(1:{::])`(2:{::])}~
The trailing ~ because I need the dyad from the resulting verb, and
the trailing ] on each because those verbs need to ignore one of the
resulting
Since it'w nagging at me (and this is still unteted code :/), here's
what I currently think i should have said:
amend=: (0:{::])`(1:{::])`(2:{::])}~
The trailing ~ because I need the dyad from the resulting verb, and
the trailing ] on each because those verbs need to ignore one of the
resulting
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 wrote:
> Oops, yes. Sorry about that.
>
> I
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 wrote:
> Raul wrote:
> "
> For example:
> amen
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
=: 1 : ' a: 1 : m'
> advswap =: 2 : (':';'u x v eval y')
>
> 1 2 3 ([ 13 advswap '}' ]) i.10
> 0 13 13 13 4 5 6 7 8 9
>
> does constant replacement instead of constant index
>
>
> - Original Message -
> From: Erl
Interesting - I'd never used "_ in that way. Works for any type:
e.g., am=: 13 : 'x 13.3j_5"_`[`]}y'
I really should get out more, vocabulary-wise.
Patrick
On Sun, 6 Jul 2014, Marc Simpson wrote: (& Raul)
Try
13"_
(see http://www.jsoftware.com/jwiki/V
Try
13"_
(see http://www.jsoftware.com/jwiki/Vocabulary/quotem)
On Sun, Jul 6, 2014 at 3:51 PM, J. Patrick Harrington
wrote:
>
> Too bad that only works for the few constant functions:
>_9: _8: ... 0: 1: ... 9:
>
> so am=: 13 : 'x 8:`[`]}y'
>3 am i. 11
> 0 1 2 8 4 5 6 7 8 9 10
>
> b
x 13"_`[`]} y
Thanks,
--
Raul
On Jul 6, 2014 10:51 AM, "J. Patrick Harrington" wrote:
>
> Too bad that only works for the few constant functions:
>_9: _8: ... 0: 1: ... 9:
>
> so am=: 13 : 'x 8:`[`]}y'
>3 am i. 11
> 0 1 2 8 4 5 6 7 8 9 10
>
> but you can't use a general value:
>
>
Too bad that only works for the few constant functions:
_9: _8: ... 0: 1: ... 9:
so am=: 13 : 'x 8:`[`]}y'
3 am i. 11
0 1 2 8 4 5 6 7 8 9 10
but you can't use a general value:
am=: 13 : 'x 13`[`]}y'
3 am i. 11
|domain error: am
| x 13`[`]}y
On Sun, 6 Jul 2014, Aai 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 ad
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 th
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.
But you can use this:
13 : 'x 0:`[`]}y'
--
Met vriendelijke groet,
@@i = Arie Groeneveld
--
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
#x27;
> advswap =: 2 : (':';'u x v eval y')
>
>1 2 3 ([ 13 advswap '}' ]) i.10
> 0 13 13 13 4 5 6 7 8 9
>
> does constant replacement instead of constant index
>
>
> - Original Message -
> From: Erling Hellenäs
> To: program
;}' ]) i.10
0 13 13 13 4 5 6 7 8 9
does constant replacement instead of constant index
- Original Message -
From: Erling Hellenäs
To: programm...@jsoftware.com
Cc:
Sent: Saturday, July 5, 2014 3:59:22 PM
Subject: [Jprogramming] Tacit J and indexed replacement
Hi all !
When you wri
There are several alternatives you have not yet noticed.
But, what problem are you trying to solve?
Thanks,
--
Raul
On Jul 5, 2014 3:59 PM, "Erling Hellenäs" wrote:
> Hi all !
>
> When you write tacit code, the index m used by Amend, syntax description
> x m} y, is a constant?
> Normally you
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 in
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