Weird Indent when using anonymous function with pipe operator

[dawee]

refmt choose to end a processing function like List.filter at the same column where the function started. It makes sense, but everytime I'm using a pipe operator with anonymous functions I'm getting this kind of results:

let result =
  list
  |> List.filter(
       fun
       | `data => true
       | `error => false,
     )
  |> List.length;

It's bugging me a bit everytime I read it because it doesn't align well with the flow. Specially when you're in an editor like VSCode, it feels like the function is not at its place:

Personally I would have expected this:

let result =
  list
  |> List.filter(
    fun
    | `data => true
    | `error => false,
  )
  |> List.length;

So that every line starts at a modulo of 2:

[dawee]

@yawaramin proposed another approach:

let result = list
  |> List.filter(fun
    | `data => true
    | `error => false)
  |> List.length;

It also works for me because it fixes the alignment of always starting on a "modulo 2 column". Plus it seems to be fairly close to what ocamlformat would do.

[anmonteiro]

discussing this in #2675