[Rd] should base R have a piping operator ?

[Rui Barradas]

Hello,

R is a functional language, pipes are not. There are even higher order 
functions such as [1] and [2].
Besides, packages are part of R, R couldn't live without them. I find 
pipes a good idea but I also find it better not to have them as part of 
base R. If you want to use them, load a package, if you don't, don't. 
This simple.

As for your example, compose, there is a StackOverflow question on it. 
See this answer [3].

[1] https://stat.ethz.ch/R-manual/R-devel/library/base/html/funprog.html
[2] https://stat.ethz.ch/R-manual/R-devel/library/base/html/Recall.html
[3] https://stackoverflow.com/a/52465956/8245406

Hope this helps,

Rui Barradas

Às 16:48 de 05/10/19, Ant F escreveu:
> Hi John,
> 
> Thanks, but the Bizzaro pipe comes with many flaws though :
> * It's not a single operator
> * It has a different precedence
> * It cannot be used in a subcall
> * The variable assigned to must be on the right
> * It doesn't trigger indentation when going to the line
> * It creates/overwrite a `.` variable in the worksace.
> 
> And it doesn't deal gracefully with some lazy evaluation edge cases such as
> :
> 
> compose <- function(f, g) { function(x) g(f(x)) }
> plus1   <- function(x) x + 1
> 
> plus2 <- plus1 %.% compose(.,plus1)
> plus2(5)
> #> [1] 7
> 
> plus1 ->.; compose(.,plus1) -> .; . -> plus2
> plus2(5)
> #> Error: C stack usage  15923776 is too close to the limit
> 
> What I propose on the other hand can always substitute any existing proper
> pipe in their standard feature, as long as the dot is made explicit.
> 
> Best regards,
> 
> Antoine
> 
> 
> 
> Le sam. 5 oct. 2019 à 16:59, John Mount <jmount using win-vector.com> a écrit :
> 
>> Actually, base R already has a pipe fairly close to the one you describe:
>> ->.;
>>
>> iris ->.; head(.) ->.; dim(.)
>> # [1] 6 5
>>
>> I've called it the Bizarro pipe (
>> http://www.win-vector.com/blog/2016/12/magrittrs-doppelganger/ ), and for
>> some reason we chickened out and didn't spend time on it in the dot pipe
>> paper ( https://journal.r-project.org/archive/2018/RJ-2018-042/index.html
>>   ).
>>
>> For documentation Bizarro pipe has the advantage that one can work out how
>> it works from the application itself, with out reference to a defining
>> function.
>>
>> On Oct 5, 2019, at 7:34 AM, Ant F <antoine.fabri using 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
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
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>>
>>
>> ---------------
>> John Mount
>> http://www.win-vector.com/
>> Our book: Practical Data Science with R
>> https://www.manning.com/books/practical-data-science-with-r-second-edition
>> <http://www.manning.com/zumel/>
>>
>>
>>
>>
>>
> 
> 	[[alternative HTML version deleted]]
> 
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