Rules for Scala 3 optional brace colons?

[molarmanful]

Hello all,

Is there a rule for automatically converting e.g.

// before
List(1, 2, 3, 4).foldLeft(0)((x, y) => x + y)

// after
List(1, 2, 3, 4).foldLeft(0): (x, y) =>
  x + y

Perhaps taking into account maxColumn, or some other preferences:

// lambda
List(1, 2, 3, 4).foldLeft(0):
  (x, y) => x + y

// auto-format cases
(x: List[Option[Int]]).map:
  case Some(x) => ???
  case None => ???

Thanks in advance!

[tgodzik]

I don't think that currently implemented, would require a feature request or a contribution.

[molarmanful]

Sure thing, I'll put it in as a feature request. Should I file it under issues or discussions?

[kitbellew]

@molarmanful what should be done with

List(1, 2, 3, 4).map(x => x * x).foldLeft(0)((x, y) => x + y)

[molarmanful]

@kitbellew I think that would probably depend on how the formatter breaks it down, e.g. if the formatter would normally do

List(1, 2, 3, 4)
  .map(x =>
    x * x
  )
  .foldLeft(0)((x, y) =>
    x + y
  )

the parentheses would be removed based on that trailing/hanging parenthesis.

List(1, 2, 3, 4)
  .map: x =>
    x * x
  .foldLeft(0): (x, y) =>
    x + y

(this is how I've basically been doing it by hand)