[Rd] should base R have a piping operator ?

David Hugh-Jones
2019-10-05T15:15:20Z

I +1 this idea, without judging the implementation details. The pipe
operator has proven vastly popular. Adding it would be
relatively easy (I think). Having it as part of the core would be a strong
guarantee of the future stability of this syntax.



On Sat, 5 Oct 2019 at 15:34, Ant F <antoine.fabri at gmail.com> wrote:

> Dear R-devel,
>
> The most popular piping operator sits in the package `magrittr` and is used
> by a huge amount of users, and imported /reexported by more and more
> packages too.
>
> Many workflows don't even make much sense without pipes nowadays, so
the
> examples in the doc will use pipes, as do the README, vignettes etc. I
> believe base R could have a piping operator so packages can use a pipe in
> their code or doc and stay dependency free.
>
> I don't suggest an operator based on complex heuristics, instead I
suggest
> a very simple and fast one (>10 times than magrittr in my tests) :
>
> `%.%` <- function (e1, e2) {
>   eval(substitute(e2), envir = list(. = e1), enclos = parent.frame())
> }
>
> iris %.% head(.) %.% dim(.)
> #> [1] 6 5
>
> The difference with magrittr is that the dots must all be explicit (which
> sits with the choice of the name), and that special magrittr features such
> as assignment in place and building functions with `. %>% head() %>%
dim()`
> are not supported.
>
> Edge cases are not surprising:
>
> ```
> x <- "a"
> x %.% quote(.)
> #> .
> x %.% substitute(.)
> #> [1] "a"
>
> f1 <- function(y) function() eval(quote(y))
> f2 <- x %.% f1(.)
> f2()
> #> [1] "a"
> ```
>
> Looking forward for your thoughts on this,
>
> Antoine
>
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