Question

How can you implement F#’s forward pipe operator in R? The operator makes it possible to easily chain a sequence of calculations. For example, when you have an input data and want to call functions foo and bar in sequence, you can write:

data |> foo |> bar

Instead of writing bar(foo(data)). The benefits are that you avoid some parentheses and the computations are written in the same order in which they are executed (left-to-right). In F#, the operator is defined as follows:

let (|>) a f = f a

It would appear that %…% can be used for binary operators, but how would this work?

Answer 1

I don’t know how well it would hold up to any real use, but this seems (?) to do what you want, at least for single-argument functions …

> "%>%" <- function(x,f) do.call(f,list(x))
> pi %>% sin
[1] 1.224606e-16
> pi %>% sin %>% cos
[1] 1
> cos(sin(pi))
[1] 1

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For what it’s worth, as of now (3 December 2021), in addition to the magrittr/tidyverse pipe (%>%), there also a native pipe |> in R (and an experimental => operator that can be enabled in the development version): see here, for example.