[Jprogramming] Tacit trains o. inverse

[Henry Rich]

    oi =: (& :. ((-([.].)) & ].)) o.
    1 oi
1&o. :.(_1&o.)

Henry Rich

On 10/14/2021 6:59 PM, Jose Mario Quintana wrote:
> I recently posed a similar question (see [0]),
>
>> This trident can be used to operate on raw noun arguments.  One can
> define first a noun boxing adverb,
>>     box=. ((<,'<') ; ])hg
>>       assert (<1 2 3) -: 1 2 3 box
>>
>> (Incidentally, I realize I am using a shotgun to kill a fly, I know I can
> easily use a pistol instead but I wonder what would be a gentle and kind
> method to kill this fly (that is, to produce a nicer equivalent adverb to
> the box adverb) using the resurrected trains or your alternative versions.)
>
> However, there were no responses.
>
> An answer to your question using the shotgun is,
>
>     minus=. ((<,'-') ; ])hg
>
>     1 minus
> _1
>
>     oi=. ((& :. ('minus' f. & ].)) o.)
>
>     1 oi
> 1&o. :.(_1&o.)
>
> A simpler answer using a pistol is,
>
>     minus=. -av
>
>     1 minus
> _1
>
>     oi=. ((& :. ('minus' f. & ].)) o.)
>
>     1 oi
> 1&o. :.((,_1)&o.)
>
> The linear representations of these versions of oi and minus are,
>
>     oi
> (& :. (((`'') (&(-@:[)) ((`(<(,'0');_))(`:6))) & ].))o.
>
>     minus
> (`'') (&(-@:[)) ((`(<(,'0');_))(`:6))
>
> In general, you can replace the - in the expression above with whatever (tacit)
> verb you might like (that is what the adverb (av) can produce for you).
>
> The tacit adverbs hg and av were written in a premodern (aka, postclassic)
> style; naturally, their products do not use any of the modern trains either.
> Again, I wonder if, say, the adverb minus could be simplified using modern
> trains.
>
> [0] [Jprogramming] New in beta-r: old stuff (jsoftware.com)
> <http://www.jsoftware.com/pipermail/programming/2021-October/058935.html>
>
>
> On Thu, Oct 14, 2021 at 4:43 PM Jan-Pieter Jacobs <
> janpieter.jacobs at gmail.com> wrote:
>> Hi all,
>>
>> I found a use for tacit trains today: making circle verbs with a sensible
>> obverse:
>>
>>     oi =: (& :. ({{-m}} & ].)) o.
>>     1 oi
>> 1&o. :.(_1&o.)
>>
>> Nice, but I have a question:
>> How does one make the {{-m}} part tacit? Or more general, how to make
> verbs
>> operate on nouns and use their results in a tacit modifier train? I guess
>> this could also be useful in experiments like structural under...
>>
>> Best regards,
>> Jan-Pieter
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