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 ?"|>" On Sat, Dec 5, 2020 at 1:19 PM <luke-tierney at 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.sarkar at gmail.com> wrote: > >> > >> On Fri, Dec 4, 2020 at 7:35 PM Duncan Murdoch <murdoch.duncan at 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?12?4?(?) 20:51 Duncan Murdoch <murdoch.duncan at 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 at r-project.org mailing list > >>>>> https://stat.ethz.ch/mailman/listinfo/r-devel > >>>> > >>>> ______________________________________________ > >>>> R-devel at r-project.org mailing list > >>>> https://stat.ethz.ch/mailman/listinfo/r-devel > >>>> > >>> > >>> ______________________________________________ > >>> R-devel at r-project.org mailing list > >>> https://stat.ethz.ch/mailman/listinfo/r-devel > >> > >> ______________________________________________ > >> R-devel at r-project.org mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-devel > > > > ______________________________________________ > > R-devel at 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-tierney at uiowa.edu > Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel-- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com
iuke-tier@ey m@iii@g oii uiow@@edu
2020-Dec-06 18:09 UTC
[Rd] [External] Re: New pipe operator
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-tierney at 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.sarkar at gmail.com> wrote: >>>> >>>> On Fri, Dec 4, 2020 at 7:35 PM Duncan Murdoch <murdoch.duncan at 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?12?4?(?) 20:51 Duncan Murdoch <murdoch.duncan at 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 at r-project.org mailing list >>>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel >>>>>> >>>>>> ______________________________________________ >>>>>> R-devel at r-project.org mailing list >>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel >>>>>> >>>>> >>>>> ______________________________________________ >>>>> R-devel at r-project.org mailing list >>>>> https://stat.ethz.ch/mailman/listinfo/r-devel >>>> >>>> ______________________________________________ >>>> R-devel at r-project.org mailing list >>>> https://stat.ethz.ch/mailman/listinfo/r-devel >>> >>> ______________________________________________ >>> R-devel at 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-tierney at uiowa.edu >> Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu >> ______________________________________________ >> R-devel at 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-tierney at uiowa.edu Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu