Sort of?
It's an optional left argument that would be part of the larger J
expression if it was present?
(That phrase was intended to show how it's used...)
Stil, we should have more havbits of trying things out.
With that in mind:
example=: p:i.3
9 */@(".@'example') 8
30
*/@(".@'example') 8
30
*/@(".@'example')
*/@(".@example)
It's better though, when you try your own examples.
Thanks,
--
Raul
On Fri, Aug 24, 2018 at 9:27 AM 'Jim Russell' via Programming
<[email protected]> wrote:
>
> Is it safe to understand that “[x]” indicates an optional left argument, and
> is not part of a the J expression?
>
> > On Aug 24, 2018, at 9:19 AM, Raul Miller <[email protected]> wrote:
> >
> > Also, in this example, ‘name’ was meant to represent a pronoun.
> >
> > Thanks,
> >
> > —
> > Raul
> >
> >> On Friday, August 24, 2018, Henry Rich <[email protected]> wrote:
> >>
> >> ".@'name' is a verb. In
> >>
> >> [x] ".@'name' y
> >>
> >> y (and x if given) are ignored, and the result is the value of (name) when
> >> the verb is executed.
> >>
> >> This is the same as it used to be, but is now faster.
> >>
> >> Henry Rich
> >>
> >>> On 8/23/2018 10:22 PM, Brian Schott wrote:
> >>>
> >>> Henry, I'm still a little lost.
> >>> Is the final `npixels` a (monadic, in this case) verb which will take a
> >>> noun argument,
> >>> or is the current value of windowsize that noun.
> >>>
> >>> If the latter, and windowsize is that noun, then what is the value of y in
> >>> the original expression `[x] ".@'name' y`?
> >>>
> >>> If the former (`npixels` is a verb -- and this is the one I'm leaning
> >>> toward), then what is the y value that is its argument?
> >>>
> >>> TIA.
> >>>
> >>> On Thu, Aug 23, 2018 at 9:41 PM, Henry Rich <[email protected]> wrote:
> >>>
> >>> Often you need for a verb to refer to the value of a name when the noun is
> >>>> executed, rather than when it is defined. So, rather than
> >>>>
> >>>> npixels =: */ windowsize
> >>>>
> >>>> which would just be a noun, you write
> >>>>
> >>>> npixels =: 3 : '*/ windowsize'
> >>>>
> >>>> to defer taking the value of (windowsize) until (npixels) is executed.
> >>>>
> >>>> In tacit code, you used to write
> >>>>
> >>>> npixels =: */ @: ". @ ('windowsize'"_)
> >>>>
> >>>> to get the same result. Recently the syntax was added to allow
> >>>>
> >>>> npixels =: */ @: ". @ 'windowsize'
> >>>>
> >>>> All that still works. But the (".) verb starts the parser and executes
> >>>> its y argument as a sentence, with a modest overhead that will matter if
> >>>> the verbs have small ranks. Now, you can write
> >>>>
> >>>> npixels =: */ @: (". @ 'windowsize')
> >>>>
> >>>> [parentheses important! make sure you see why]. When (npixels) is
> >>>> defined, this form will detect that the argument to (".) is a single
> >>>> name.
> >>>> When (npixels) is executed, the name will be evaluated without going
> >>>> through the overhead of starting a sentence.
> >>>>
> >>>> Henry Rich
> >>>>
> >>>> ----------------------------------------------------------------------
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> >>>
> >>
> >>
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