[Rd] New pipe operator

[Hadley Wickham]

I just wanted to pipe in here (HA HA) to say that I agree with Kevin.
I've never loved the complicated magrittr rule (which has personally
tripped me up a couple of times) and I think the compact inline
function syntax provides a more general solution. It is a bit more
typing, and it will require a little time for your eyes to get used to
the new syntax, but overall I think it's a better solution.

In general, I think the base pipe does an excellent job of taking what
we've learned from 6 years of magrittr, keeping what has been most
successful while discarding complications around the edges.

Hadley

On Mon, Dec 7, 2020 at 1:05 PM Kevin Ushey <kevinushey using gmail.com> wrote:
>
> IMHO the use of anonymous functions is a very clean solution to the
> placeholder problem, and the shorthand lambda syntax makes it much
> more ergonomic to use. Pipe implementations that crawl the RHS for
> usages of `.` are going to be more expensive than the alternatives. It
> is nice that the `|>` operator is effectively the same as a regular R
> function call, and given the identical semantics could then also be
> reasoned about the same way regular R function calls are.
>
> I also agree usages of the `.` placeholder can make the code more
> challenging to read, since understanding the behavior of a piped
> expression then requires scouring the RHS for usages of `.`, which can
> be challenging in dense code. Piping to an anonymous function makes
> the intent clear to the reader: the programmer is likely piping to an
> anonymous function because they care where the argument is used in the
> call, and so the reader of code should be aware of that.
>
> Best,
> Kevin
>
>
>
> On Mon, Dec 7, 2020 at 10:35 AM Gabor Grothendieck
> <ggrothendieck using gmail.com> wrote:
> >
> > On Mon, Dec 7, 2020 at 12:54 PM Duncan Murdoch <murdoch.duncan using gmail.com> wrote:
> > > An advantage of the current implementation is that it's simple and easy
> > > to understand.  Once you make it a user-modifiable binary operator,
> > > things will go kind of nuts.
> > >
> > > For example, I doubt if there are many users of magrittr's pipe who
> > > really understand its subtleties, e.g. the example in Luke's paper where
> > > 1 %>% c(., 2) gives c(1,2), but 1 %>% c(c(.), 2) gives c(1, 1, 2). (And
> > > I could add 1 %>% c(c(.), 2, .) and  1 %>% c(c(.), 2, . + 2)  to
> > > continue the fun.)
> >
> > The rule is not so complicated.  Automatic insertion is done unless
> > you use dot in the top level function or if you surround it with
> > {...}.  It really makes sense since if you use gsub(pattern,
> > replacement, .) then surely you don't want automatic insertion and if
> > you surround it with { ... } then you are explicitly telling it not
> > to.
> >
> > Assuming the existence of placeholders a possible simplification would
> > be to NOT do automatic insertion if { ... } is used and to use it
> > otherwise although personally having used it for some time I find the
> > existing rule in magrittr generally does what you want.
> >
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