] is an identify function. Specifically, the value of its result is
its right argument.
An expression of the form f g h (where f, g and h are verbs) is a
fork: the arguments to g are the results of f and h applied to the
arguments of the fork.
And, finally, an expression of the form i g h (where i is a noun) is
also a fork, because i gets converted to the verb i"_ (which basically
just means that the left argument to g is i).
------
Meanwhile, these expressions have equivalent results, for nouns id and k:
k { id
{&id k
k { id
id {~ k
(id {~ ]) k
------
Meanwhile, these are different from the above, but equivalent to each other:
id&{~ k
k id&{ k
... but you probably do not want to go there right now...
------
Finally, for installation problems (getting J to run on fedora), if
you have time, maybe post the errors you were getting (along with what
you did to get them) to the general@jsoftware list?
Thanks,
--
Raul
On Mon, May 29, 2017 at 11:15 AM, Michael Rice <[email protected]> wrote:
> (id {~ ])?
>
> I don't understand the usage of ] in the above.
>
> From the NuVoc docs:
>
> Use in the J session to both display a noun and assign it to a name with a
> single sentence
>
> ] z=: i:2
> _2 _1 0 1 2
>
> Typo?
>
> (id {~ ]) move?
>
> What does it expand to? Where's the assignment of a function to a name?
>
> Earlier, I tried to curry the { function
>
> move { id
>
> to
>
> f =: (id & {~)
>
> Seemed like that should work, like this
>
> f 0 2 5 => 3 by 15 array
>
> but I think I got a syntax error when I tried it.
>
> I couldn't get get J running on my Fedora 24 install (where I am now), so
> put it on Win 10 on my dual-boot box and will get back to it after I run
> some errands.
>
> Thanks, all.
>
>
>
> On Mon, May 29, 2017 at 10:27 AM, Raul Miller <[email protected]> wrote:
>
>> Hmm...
>>
>> First, here's an expression for a 15 by 15 identity matrix:
>>
>> id=: 15 15$16{.1
>>
>> But (id {~) is invalid syntax, so perhaps, instead use =&(i.15)"0
>>
>> For example:
>>
>> =&(i.15)"0 ] 2 3 5
>> 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0
>> 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0
>> 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0
>>
>> That said, (id {~ ]) is syntactically valid and does the same thing
>> (except for arguments outside the domain).
>>
>> I hope this helps,
>>
>> --
>> Raul
>>
>>
>> On Mon, May 29, 2017 at 9:22 AM, Michael Rice <[email protected]> wrote:
>> > Thanks.
>> >
>> > I found that after I couldn't find it and wrote my own, but it seemed to
>> be
>> > changing one of my function parameters, the left one, so I moved back to
>> my
>> > definition.
>> >
>> > I'm again having a similar problem stringing these verbs, adverbs, etc.
>> > together to form the function I want.
>> >
>> > I created an 15 by 15 identity matrix, call it id, and substituted this
>> >
>> > (1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 |.!.0~
>> > 3 1 $ -)
>> >
>> > for this
>> >
>> > (id {~)
>> >
>> > Much cleaner and, no doubt, faster. Win. Win.
>> >
>> > Naively, I thought this simple substitution of the two would work
>> >
>> > make_move =: ((+. *. -.@:*.) +./) (id {~)
>> >
>> > Nope. Syntax error.
>> >
>> > Have already tried several other variations this AM with the same result.
>> >
>> > I'm using "Learning J" as a reference and NuVoc.
>> >
>> > http://www.jsoftware.com/help/learning/contents.htm
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > On Sun, May 28, 2017 at 9:57 PM, David Lambert <[email protected]>
>> wrote:
>> >
>> >> xor can be not equal ~:
>> >>
>> >> or bitwise 2b10110 b.
>> >>
>> >>
>> >>
>> >> On 05/28/2017 08:00 AM, [email protected] wrote:
>> >>
>> >>> Message: 5
>> >>> Date: Sat, 27 May 2017 23:51:29 -0400
>> >>> From: Michael Rice<[email protected]>
>> >>> To: programming<[email protected]>
>> >>> Subject: Re: [Jprogramming] Function creation, without creating
>> >>> subfunctions
>> >>> Message-ID:
>> >>> <CAGw08vM_5CttMFY45F6zAAto-doycQYkXqRf8uRWC=0Ug9xcOw@mail.
>> >>> gmail.com>
>> >>> Content-Type: text/plain; charset="UTF-8"
>> >>>
>> >>> Yes, that worked. New board created, without changing the old board or
>> the
>> >>> move.
>> >>>
>> >>> board =: 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1
>> >>> move =: 0 2 5
>> >>> make_move =: ((+. *. -.@:*.) +./) (1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
>> >>> |.!.0~
>> >>> 3 1 $ -)
>> >>> board make_move move
>> >>> 0 1 0 1 1 1 1 1 1 1 1 1 1 1 1
>> >>> board
>> >>> 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1
>> >>> move
>> >>> 0 2 5
>> >>>
>> >>
>> >> ----------------------------------------------------------------------
>> >> 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
