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trait Applicative[M[_]]
sealed trait MA[M[_], A] {
def sequence[N[_], B](implicit a: A <:< N[B], n: Applicative[N]): N[M[B]] = sys.error("stub")
// def sequence3[N[_], B]()(implicit a: A <:< N[B], n: Applicative[N]): N[M[B]] = sys.error("stub")
}
object test {
implicit def ListMA[A](l: List[A]): MA[List, A] = sys.error("stub")
implicit val ao: Applicative[Option] = sys.error("stub")
/* This compiles OK:
(Nil: List[Option[Int]]).sequence3(): Option[List[Int]]
*/
// BUG: error: immutable is not an enclosing class
// !!! No line number is reported with the error
(Nil: List[Option[Int]]).sequence: Option[List[Int]]
(List[Option[Int]]()).sequence: Option[List[Int]]
}
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