[Rd] Additional an example for the forward pipe operator's documentation

[Gabor Grothendieck]

These also work in this particular case although not in general and the Call:
line in the output differs:

  mtcars |> subset(cyl == 4) |> with(lm(mpg ~ disp))
  mtcars |> with(lm(mpg ~ disp, subset = cyl == 4))

On Sat, Jun 19, 2021 at 7:23 AM Erez Shomron <erezshomron using mykolab.com> wrote:
>
> Hello,
>
>
> While playing around with the new forward pipe operator I've noticed
> there's a possibly overlooked usage for the operator, which would be
> very beneficial to document.
>
> Whenever you want the LHS to be passed to an argument other than the
> first, the documented example demonstrates how to do that with an
> anonymous function.
>
>
> However the syntax is less than ideal (aesthetically):
>
>
> mtcars |> subset(cyl == 4) |> (function(d) lm(mpg ~ disp, data = d))()
>
>
> Fortunately there's a better, undocumented option using named arguments:
>
>
> mtcars |> subset(cyl == 4) |> lm(formula = mpg ~ disp)
>
>
> The reason this works, is because of how R matches arguments. As the
> language definition states, first named arguments are matched, then
> partial matching, and only afterwards positional arguments are matched.
>
>
> I think people that are frustrated with former syntax would be happy to
> know the latter option exists.
>
>
> That's just my opinion.
>
>
> Thank you for reading,
>
> Erez
>
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