Why is that ambiguous? It works in magrittr. > library(magrittr) > 1 %>% `+`() [1] 1
On Sun, Dec 6, 2020 at 1:09 PM <luke-tier...@uiowa.edu> wrote: > > On Sun, 6 Dec 2020, Gabor Grothendieck wrote: > > > The following gives an error. > > > > 1 |> `+`(2) > > ## Error: function '+' is not supported in RHS call of a pipe > > > > 1 |> `+`() > > ## Error: function '+' is not supported in RHS call of a pipe > > > > but this does work: > > > > 1 |> (`+`)(2) > > ## [1] 3 > > > > 1 |> (`+`)() > > ## [1] 1 > > > > The error message suggests that this was intentional. > > It isn't mentioned in ?"|>" > > ?"|>" says: > > To avoid ambiguities, functions in ‘rhs’ calls may not > be syntactically special, such as ‘+’ or ‘if’. > > (used to say lhs; fixed now). > > Best, > > luke > > > > > On Sat, Dec 5, 2020 at 1:19 PM <luke-tier...@uiowa.edu> wrote: > >> > >> We went back and forth on this several times. The key advantage of > >> requiring parentheses is to keep things simple and consistent. Let's > >> get some experience with that. If experience shows requiring > >> parentheses creates too many issues then we can add the option of > >> dropping them later (with special handling of :: and :::). It's easier > >> to add flexibility and complexity than to restrict it after the fact. > >> > >> Best, > >> > >> luke > >> > >> On Sat, 5 Dec 2020, Hugh Parsonage wrote: > >> > >>> I'm surprised by the aversion to > >>> > >>> mtcars |> nrow > >>> > >>> over > >>> > >>> mtcars |> nrow() > >>> > >>> and I think the decision to disallow the former should be > >>> reconsidered. The pipe operator is only going to be used when the rhs > >>> is a function, so there is no ambiguity with omitting the parentheses. > >>> If it's disallowed, it becomes inconsistent with other treatments like > >>> sapply(mtcars, typeof) where sapply(mtcars, typeof()) would just be > >>> noise. I'm not sure why this decision was taken > >>> > >>> If the only issue is with the double (and triple) colon operator, then > >>> ideally `mtcars |> base::head` should resolve to `base::head(mtcars)` > >>> -- in other words, demote the precedence of |> > >>> > >>> Obviously (looking at the R-Syntax branch) this decision was > >>> considered, put into place, then dropped, but I can't see why > >>> precisely. > >>> > >>> Best, > >>> > >>> > >>> Hugh. > >>> > >>> > >>> > >>> > >>> > >>> > >>> > >>> On Sat, 5 Dec 2020 at 04:07, Deepayan Sarkar <deepayan.sar...@gmail.com> > >>> wrote: > >>>> > >>>> On Fri, Dec 4, 2020 at 7:35 PM Duncan Murdoch <murdoch.dun...@gmail.com> > >>>> wrote: > >>>>> > >>>>> On 04/12/2020 8:13 a.m., Hiroaki Yutani wrote: > >>>>>>> Error: function '::' not supported in RHS call of a pipe > >>>>>> > >>>>>> To me, this error looks much more friendly than magrittr's error. > >>>>>> Some of them got too used to specify functions without (). This > >>>>>> is OK until they use `::`, but when they need to use it, it takes > >>>>>> hours to figure out why > >>>>>> > >>>>>> mtcars %>% base::head > >>>>>> #> Error in .::base : unused argument (head) > >>>>>> > >>>>>> won't work but > >>>>>> > >>>>>> mtcars %>% head > >>>>>> > >>>>>> works. I think this is a too harsh lesson for ordinary R users to > >>>>>> learn `::` is a function. I've been wanting for magrittr to drop the > >>>>>> support for a function name without () to avoid this confusion, > >>>>>> so I would very much welcome the new pipe operator's behavior. > >>>>>> Thank you all the developers who implemented this! > >>>>> > >>>>> I agree, it's an improvement on the corresponding magrittr error. > >>>>> > >>>>> I think the semantics of not evaluating the RHS, but treating the pipe > >>>>> as purely syntactical is a good decision. > >>>>> > >>>>> I'm not sure I like the recommended way to pipe into a particular > >>>>> argument: > >>>>> > >>>>> mtcars |> subset(cyl == 4) |> \(d) lm(mpg ~ disp, data = d) > >>>>> > >>>>> or > >>>>> > >>>>> mtcars |> subset(cyl == 4) |> function(d) lm(mpg ~ disp, data = d) > >>>>> > >>>>> both of which are equivalent to > >>>>> > >>>>> mtcars |> subset(cyl == 4) |> (function(d) lm(mpg ~ disp, data = > >>>>> d))() > >>>>> > >>>>> It's tempting to suggest it should allow something like > >>>>> > >>>>> mtcars |> subset(cyl == 4) |> lm(mpg ~ disp, data = .) > >>>> > >>>> Which is really not that far off from > >>>> > >>>> mtcars |> subset(cyl == 4) |> \(.) lm(mpg ~ disp, data = .) > >>>> > >>>> once you get used to it. > >>>> > >>>> One consequence of the implementation is that it's not clear how > >>>> multiple occurrences of the placeholder would be interpreted. With > >>>> magrittr, > >>>> > >>>> sort(runif(10)) %>% ecdf(.)(.) > >>>> ## [1] 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 > >>>> > >>>> This is probably what you would expect, if you expect it to work at all, > >>>> and not > >>>> > >>>> ecdf(sort(runif(10)))(sort(runif(10))) > >>>> > >>>> There would be no such ambiguity with anonymous functions > >>>> > >>>> sort(runif(10)) |> \(.) ecdf(.)(.) > >>>> > >>>> -Deepayan > >>>> > >>>>> which would be expanded to something equivalent to the other versions: > >>>>> but that makes it quite a bit more complicated. (Maybe _ or \. should > >>>>> be used instead of ., since those are not legal variable names.) > >>>>> > >>>>> I don't think there should be an attempt to copy magrittr's special > >>>>> casing of how . is used in determining whether to also include the > >>>>> previous value as first argument. > >>>>> > >>>>> Duncan Murdoch > >>>>> > >>>>> > >>>>>> > >>>>>> Best, > >>>>>> Hiroaki Yutani > >>>>>> > >>>>>> 2020年12月4日(金) 20:51 Duncan Murdoch <murdoch.dun...@gmail.com>: > >>>>>>> > >>>>>>> Just saw this on the R-devel news: > >>>>>>> > >>>>>>> > >>>>>>> R now provides a simple native pipe syntax ‘|>’ as well as a shorthand > >>>>>>> notation for creating functions, e.g. ‘\(x) x + 1’ is parsed as > >>>>>>> ‘function(x) x + 1’. The pipe implementation as a syntax > >>>>>>> transformation > >>>>>>> was motivated by suggestions from Jim Hester and Lionel Henry. These > >>>>>>> features are experimental and may change prior to release. > >>>>>>> > >>>>>>> > >>>>>>> This is a good addition; by using "|>" instead of "%>%" there should > >>>>>>> be > >>>>>>> a chance to get operator precedence right. That said, the ?Syntax > >>>>>>> help > >>>>>>> topic hasn't been updated, so I'm not sure where it fits in. > >>>>>>> > >>>>>>> There are some choices that take a little getting used to: > >>>>>>> > >>>>>>> > mtcars |> head > >>>>>>> Error: The pipe operator requires a function call or an anonymous > >>>>>>> function expression as RHS > >>>>>>> > >>>>>>> (I need to say mtcars |> head() instead.) This sometimes leads to > >>>>>>> error > >>>>>>> messages that are somewhat confusing: > >>>>>>> > >>>>>>> > mtcars |> magrittr::debug_pipe |> head > >>>>>>> Error: function '::' not supported in RHS call of a pipe > >>>>>>> > >>>>>>> but > >>>>>>> > >>>>>>> mtcars |> magrittr::debug_pipe() |> head() > >>>>>>> > >>>>>>> works. > >>>>>>> > >>>>>>> Overall, I think this is a great addition, though it's going to be > >>>>>>> disruptive for a while. > >>>>>>> > >>>>>>> Duncan Murdoch > >>>>>>> > >>>>>>> ______________________________________________ > >>>>>>> R-devel@r-project.org mailing list > >>>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel > >>>>>> > >>>>>> ______________________________________________ > >>>>>> R-devel@r-project.org mailing list > >>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel > >>>>>> > >>>>> > >>>>> ______________________________________________ > >>>>> R-devel@r-project.org mailing list > >>>>> https://stat.ethz.ch/mailman/listinfo/r-devel > >>>> > >>>> ______________________________________________ > >>>> R-devel@r-project.org mailing list > >>>> https://stat.ethz.ch/mailman/listinfo/r-devel > >>> > >>> ______________________________________________ > >>> R-devel@r-project.org mailing list > >>> https://stat.ethz.ch/mailman/listinfo/r-devel > >>> > >> > >> -- > >> Luke Tierney > >> Ralph E. Wareham Professor of Mathematical Sciences > >> University of Iowa Phone: 319-335-3386 > >> Department of Statistics and Fax: 319-335-3017 > >> Actuarial Science > >> 241 Schaeffer Hall email: luke-tier...@uiowa.edu > >> Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu > >> ______________________________________________ > >> R-devel@r-project.org mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-devel > > > > > > > > > > -- > Luke Tierney > Ralph E. Wareham Professor of Mathematical Sciences > University of Iowa Phone: 319-335-3386 > Department of Statistics and Fax: 319-335-3017 > Actuarial Science > 241 Schaeffer Hall email: luke-tier...@uiowa.edu > Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
