Closed
Description
Compiler version
3.5.0-RC1, the issue is not present in 3.4.2
Minimized code
https://scastie.scala-lang.org/mrdziuban/lnO61Y1VSSy2xu5NuyAg8w
trait WrapperType[A]
case class Foo[A]()
case class Bar[A]()
type FooToBar[D[_]] = [A] =>> D[Unit] match {
case Foo[Unit] => Bar[A]
}
case class Test()
object Test {
implicit val wrapperType: WrapperType[Bar[Test]] = new WrapperType[Bar[Test]] {}
}
val test = summon[WrapperType[FooToBar[Foo][Test]]]Output
16 |val test = summon[WrapperType[FooToBar[Foo][Test]]]
| ^
|No given instance of type WrapperType[FooToBar[Foo][Test]] was found for parameter x of method summon in object Predef
|
|The following import might fix the problem:
|
| import Test.wrapperType
|Expectation
Test.wrapperType should satisfy the implicit search of the summon call.
Interestingly, if I change FooToBar to not return a type lambda, then everything compiles correctly, i.e.
type FooToBar[D[_], A] = D[Unit] match {
case Foo[Unit] => Bar[A]
}
// ...
val test = summon[WrapperType[FooToBar[Foo, Test]]]