> From: "Raul Miller" <[EMAIL PROTECTED]>
>
> On 9/14/07, neville holmes <[EMAIL PROTECTED]> wrote:
> > {.[.}.
> > so that the adverb
> > a =. {.[.}.
> > would allow f a x to apply f between the head of x and the
> > behead of x. Similarly, x f a y would use x {. y and x }. y as
> > arguments for f.
>
> a=: /(@({. ,: }.))
> + a 2 3 5 7
> 5 7 9
> 2 + a 10^i.4
> 101 1010
Well, yes, it could be done that way, but surely {.[.}. is
significantly simpler and easier to understand than
/(@({. ,: }.)) especially for learners and dabblers.
>
> > Other examples:
> >
> > b =. ] ,: [. NB. adverb
> >
> > then f b x would stack x over f x and x f b y would stack y
> > over x f y.
>
> b=: ^:0 1
> +/ b i.3
> 0 1 2
> 3 0 0
> 3 *b 4
> 4 12
Yes, that's very neat and I'll find use for it if I ever get
back to writing about J. But what you're doing is finding
different ways for doing ordinary things that I would argue
should all be done the same way.
>
> > There are ways of defining such adverbs and conjunctions
> > without [. and ]. I suppose, but surely [. and ]. would make
> > such constructs much easier to produce and understand.
>
Note that I have not been justifying my request as allowing
things to be done that couldn't be done otherwise. However,
it could be that my [. and ]. would allow new things to be
done; I'm not in touch enough with J to be confident that
they would.
But, because they would coerce a tacit definition to be either
a conjunction or an adverb, depending on whether ]. was used
or not, and because they mimic and conform to [ and ],
they could in effect be used to define a "conjunction" that is a
verb/function with four arguments or a formidable conjunction
with four operands, for example. And it would do so simply.
Or at least it seems so to me.
> J's [. and ]. (before they were omitted) did not seem to produce
> easy to understand expressions. (The style used in my 'a',
> above, is somewhat representative of how you would use those
> symbols -- though a is somewhat simpler than those kinds of
> examples.)
>
The prior [. and ]. were called lev and dex and do not correspond
at all to what I'm suggesting. Indeed I don't think I ever
found a use for dex, and lev was mainly useful for defining more
than one verb on a single line. Indeed, when lev and dex were
removed I had hoped that that was to free up the primitive
symbols for use in the fashion I'm suggesting.
As a dilettante tacit-only J-er I am very discouraged that this
has not been done.
Neville Holmes, P.O.Box 404, Mowbray 7248, Tasmania
Normal e-mail: [EMAIL PROTECTED]
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