I will not dare to explain it again after Dan has done so; see,
http://www.jsoftware.com/pipermail/programming/2013-January/031249.html
the form is slightly different but the same logic applies. In my opinion,
that thread and the related one:
http://www.jsoftware.com/pipermail/programming/2013-January/031260.html are
worth reading, including the dissenting arguments..
By the way, I miswrote, Cloak=. (0:`)(,^:) is an adverb (not a
conjunction). Moreover, for a tacit writer, I for one, it feels indeed as
deus (verbalized adverb or conjunction) ex machina (^: or an alternative).
On Fri, Feb 21, 2014 at 1:11 PM, Pascal Jasmin <godspiral2...@yahoo.ca>wrote:
> neat.
>
> tie
> ,^:(0:``)
>
> tie&'' f.
> ,^:(0:``)&''
>
> which is using the gerund (v1`v2) version of ^: . This appears to be
> undocumented in that v2 here is a conjunction(`). I assume that using an
> adverb as v2 is impossible?
>
> The other peculiarity is that v1 is 0: which means that , never executes.
> Is that right?
>
>
>
> ----- Original Message -----
> From: Jose Mario Quintana <jose.mario.quint...@gmail.com>
> To: Programming forum <programm...@jsoftware.com>
> Cc:
> Sent: Friday, February 21, 2014 11:31:56 AM
> Subject: Re: [Jprogramming] Generating code from templates
>
> The verbalized conjunctions tie and rank can be produced as follows:
>
> 9!:14 ''
> j701/2011-01-10/11:25
>
> Cloak=. (0:`)(,^:) NB. Conjunction to cloak adverbs and conjunctions as
> verbs
> Cloak=. (5!:1@<'Cloak')Cloak NB. Cloaking Cloak
>
> 'tie rank'=. (Cloak @: < each) @: ;: '` "' NB. Cloaking tie (`) and rank
> (")
>
>
> cf=. {.@(tie&'')@(rank&_)"0 f.
> 100"_`(200"_)`(300"_) -: cf 100 200 300
> 1
>
>
> Cloak can also be produced without using ^: (although with a caveat).
> Members interested in following the beginnings of the story can look at
> http://www.jsoftware.com/pipermail/programming/2013-March/031883.html .
>
>
> On Thu, Feb 20, 2014 at 8:52 PM, Raul Miller <rauldmil...@gmail.com>
> wrote:
>
> > This would be more fun if you provided definitions for tie and rank (and
> > others you use) in an addon.
> >
> > Without that, it feels like deus ex machina (and does not execute for me
> > like it does for you).
> >
> > Thanks,
> >
> > --
> > Raul
> >
> >
> > On Thu, Feb 20, 2014 at 6:06 PM, Jose Mario Quintana <
> > jose.mario.quint...@gmail.com> wrote:
> >
> > > "
> > > Anyway, thought I'd share, and see if anyone else has useful tools for
> > > manipulating J code (metaprogramming).
> > > "
> > >
> > > Dan, I will try to show some meta-programming exercises soon. I am
> > jumping
> > > into the darkness hoping that I will land well; so far, so good. In
> the
> > > meantime, the following is a F^4 underground verb corresponding to
> Raul's
> > > explicit verb (using verbalized primitive conjunctions):
> > >
> > > cf=. {.@(tie&'')@(rank&_)"0 f.
> > >
> > > 100"_`(200"_)`(300"_) -: cf 100 200 300
> > > 1
> > >
> > >
> > >
> > > On Thu, Feb 20, 2014 at 2:39 PM, Dan Bron <j...@bron.us> wrote:
> > >
> > > > There was a question on StackOverflow today on generating constant
> > > > functions from the items of an array. As in, 100 200 300 <==>
> > > > 100"_`(200"_)`(300"_) .
> > > >
> > > > As a more general question, how can we specify code templates and
> then
> > > use
> > > > them to dynamically produce gerunds for later execution? *
> > > >
> > > > Here's one idiom I've found useful in such situations:
> > > >
> > > > substit =: [^:(__-:])L:_ 0
> > > >
> > > > template =: __"_ NB. The template; note the __
> > > > TEMPLATE =: {. template f.`'' NB. Atomic rep of template
> > > >
> > > > GERUND =: TEMPLATE substit"_1 _~ 100 * 1 + i.3
> > > >
> > > > GERUND`:6
> > > > (100"_) (200"_) 300"_
> > > >
> > > > GERUND@.0
> > > > 100"_
> > > >
> > > > GERUND@.2 'hello'
> > > > 300
> > > >
> > > > The basic idea is to "fill in the blanks" in the template with the
> > > inputs.
> > > > Here, the blank is __ (negative infinity), so we look for that in the
> > > > gerund template, and when we find it, we replace it with the input. I
> > > kind
> > > > of like how the verb does this: first, we only bother looking at
> level
> > 0
> > > > (because __ is unboxed, so it will never appear above level 0), and
> > > > second, the verb is passive until __ is detected (because ^:(]-:__)
> is
> > > > ^:0, i.e. "do nothing and just return the RHA" until then).
> > > >
> > > > One possible issue is what we use to denote "blank". If we're going
> to
> > > > allow users to pass in any gerund, then he could potentially want to
> > > > include __ as part of the code to be produced, rather than replaced.
> > > There
> > > > are a couple possible ways to address that limitation. First, we
> could
> > > use
> > > > a value which a user is very unlikely to want to produce (as opposed
> to
> > > > replace), i.e. _. :
> > > >
> > > > substit =: [^:(1-:128!:5@])L:_ 0
> > > > SPARTA =: ({. _."_ `'') substit"_1 _~ 300
> > > > SPARTA`:6
> > > > 300"_
> > > >
> > > > Or, we could define substit as an adverb (adjective), which takes the
> > > > "blank" as an argument:
> > > >
> > > > Substit =: (-:&) (@]) ([^:) (L:_ 0)
> > > >
> > > > substit =: 'blank' Substit
> > > > substit
> > > > [^:(-:&'blank'@])L:_ 0
> > > >
> > > > ; , ((< {. 'blank'&;`'') substit~&.> ;:'fill in the blanks' )`:0
> '!'
> > > > fill!in!the!blanks!
> > > >
> > > > But if we do that, we have to start wondering about the 0 in L:_ 0 ,
> > > > because the user's "blank" might be boxed, and therefore have L.>0 .
> Of
> > > > course, we could fix this up by making the L: dynamic:
> > > >
> > > > Substit =: adverb : '[^:(m-:])L:(_,L.m)'
> > > >
> > > > NOTNULL =: ({. ~:&a:` '') a: Substit~ <'#N/A#'
> > > > NOTNULL`:6
> > > > ~:&(<'#N/A#')
> > > >
> > > > But it might be more fun to go meta-meta:
> > > >
> > > > (({. substit f.`'') substit~ _999)`:6
> > > > [^:(_999 -: ])L:_ 0
> > > >
> > > > Here, define the "standard" blank to be __, and then let the user
> > change
> > > it
> > > > by using substit :)
> > > >
> > > > Anyway, thought I'd share, and see if anyone else has useful tools
> for
> > > > manipulating J code (metaprogramming).
> > > >
> > > > -Dan
> > > >
> > > > * For a recent example of where such metaprogramming might be
> useful,
> > or
> > > > convenient, see the postscript of:
> > > >
> > > >
> > > >
> > http://www.jsoftware.com/pipermail/programming/2013-December/034373.html
> > > >
> > > > Other examples can be found with a forum archive search for the
> string
> > > L:0
> > > > _
> > > >
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>
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