On Apr 21, 2023, at 1:01 PM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
?On 21/04/2023 12:16 p.m., Michael Milton wrote:
I'm afraid I don't understand. I know that parsing `+`(1, 1) returns a result equivalent to `1 + 1`, but why does that impose a restriction on parsing the pipe operator? What is the downside of allowing arbitrary RHS functions?
I thought the decision to exclude "_ + 1" happens after enough parsing has happened so that the code making the decision can't tell the difference between "_ + 1" and "`+`(_, 1)". I might be wrong about that, but this suggests it:
Error in quote("_" + 1) : invalid use of pipe placeholder (<input>:1:0)
Error in quote("_" + 1) : invalid use of pipe placeholder (<input>:1:0)
On the other hand, this works:
> quote(x |> `+`(e1 = _, 1))
x + 1
So maybe `+`() is fine after all.
Duncan Murdoch