[External] brief update on the pipe operator in R-devel
'=>' can be defined as a function. E.g., it could be the logical "implies"
function:
> `=>` <- function(x, y) !x | y
> TRUE => FALSE
[1] FALSE
> FALSE => TRUE
[1] TRUE
It might be nice then to have deparse() display it as an infix operator
instead of the current prefix:
> deparse(quote(p => q))
[1] "`=>`(p, q)"
There was a user who recently wrote asking for an infix operator like -> or
=> that would deparse nicely for use in some sort of model specification.
When used with |>, the parser will turn the |> and => into an ordinary
looking function call so deparsing is irrelevant.
> deparse(quote(x |> tmp => f(7,arg2=tmp)))
[1] "f(7, arg2 = x)"
-Bill
On Tue, Jan 12, 2021 at 12:01 PM Dirk Eddelbuettel <edd at debian.org> wrote:
On 12 January 2021 at 20:38, I?aki Ucar wrote: | On Tue, 12 Jan 2021 at 20:23, <luke-tierney at uiowa.edu> wrote: | > | > After some discussions we've settled on a syntax of the form | > | > mtcars |> subset(cyl == 4) |> d => lm(mpg ~ disp, data = d) | > | > to handle cases where the pipe lhs needs to be passed to an argument | > other than the first of the function called on the rhs. This seems a | > to be a reasonable balance between making these non-standard cases | > easy to see but still easy to write. This is now committed to R-devel. | | Interesting. Is the use of "d =>" restricted to pipelines? In other | words, I think that it shouldn't be equivalent to "function(d)", i.e., | that this: | | x <- d => lm(mpg ~ disp, data = d) | | shouldn't work. Looks like your wish was already granted:
> mtcars |> subset(cyl == 4) |> d => lm(mpg ~ disp, data = d)
Call:
lm(formula = mpg ~ disp, data = subset(mtcars, cyl == 4))
Coefficients:
(Intercept) disp
40.872 -0.135
> d => lm(mpg ~ disp, data = d)
Error in `=>`(d, lm(mpg ~ disp, data = d)) : could not find function "=>"
> x <- d => lm(mpg ~ disp, data = d)
Error in `=>`(d, lm(mpg ~ disp, data = d)) : could not find function "=>"
>
Dirk -- https://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
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