Function value signature for generics, context functions

import scala.concurrent.duration.*
import scala.concurrent.{Await, ExecutionContext, Future}

def processOption[A](opt: Option[A]): String = opt match {
  case Some(v) => s"[$v]"
  case None    => "[]"
}

@main def main(): Unit = {

  /** Generics in functions
    */
  val processOptionFunction: [A] => Option[A] => String = {
    [A] => (opt: Option[A]) => processOption(opt)
  }

  processOptionFunction(Some(1))

  /** Context functions
    */
  def f(x: Int)(using ExecutionContext): Future[Int] = Future { x * 100 }
  val f_signature: Int => ExecutionContext ?=> Future[Int] = f

  val g: ExecutionContext ?=> Int => Future[Int] = (x: Int) => Future { x + 1 }

  given ExecutionContext = scala.concurrent.ExecutionContext.global

  val c = for {
    a <- f(2)
    b <- g(4)
  } yield a + b

  val r = Await.result(c, 3.seconds)
  println(r) // 205
}