`Raises` and `Handles` aliases on Scala 3?

[armanbilge]

Just wanted to jot this idea down, someone feel free to turn it into a PR :) miraculously, this syntax seems to compile/auto-infer in Scastie. LOL, I lied, it was a "miracle". Well, maybe someone can workshop this 😅

abstract class IO[+A]
trait Raise[F[_], E]
trait MyError

type Raises[F[_], E] = [A] => Raise[F, E] ?=> F[A]

type Rtn = IO[String] Raises MyError

The idea is this allows to write:

def foo(bar: Bar): IO[Baz] Raises Qux

instead of

def foo(bar: Bar)(using Raise[IO, Qux]): IO[Baz]

[kubukoz]

I do NOT understand why it doesn't work even with infix type.

Edit: I understand now. Still, stuck at this:

abstract class IO[+A]
trait Raise[F[_], E]
trait MyError

infix type Raises[FA, E] =
  FA match {
    case f[a] => Raise[f, E] ?=> f[a]
  }

type Rtn = IO[String] Raises[MyError]

Apparently you can't match on types like that if f is abstract :/