Refactor to Single Abstract Method (SAM)

[benjamingeer]

Is your feature request related to a problem? Please describe.

Lambda syntax for Single Abstract Method (SAM) types improves interoperability with Java libraries, and is more concise than the alternative syntax, but it's cumbersome to change from one to the other manually.

Describe the solution you'd like

Taking an example from Stackoverflow, given a trait like this:

trait Foo {
  def m1(id : Int) : Try[String]
}

And an expression like this:

val g : Foo = new Foo {
  override def m1(id: Int): Try[String] = Success("Good job")
}

I'd like Metals to be able to refactor the expression to produce this:

val g : Foo = (id: Int) => Success("Good job")

Describe alternatives you've considered

This can be done manually, but it's more time-consuming.

Additional contex

No response

Search terms

SAM Java refactor

[kubukoz]

I'd just like to point out that this isn't a purely syntactic refactor unfortunately: if the type annotation isn't present, Scala can't tell what interface is necessary.

I would also love this feature though!

[tgodzik]

I think this is doable via the presentation compiler, the problem is detecting the places where it can be done. Would be great if the presentation compiler returned a warning where it can be converted.