Error related to repositoriesTask

[lilyevsky]

I used to override the "repositories" from CoursierModule trait. Now it says (using mill 0.9.6) that it is deprecated, and I should use repositoriesTask instead. Here is the fragment of my updated build.sc:

val lnRepositories = Seq(MavenRepository(localUrl),
    MavenRepository(nexusPublicUrl, Some(Authentication(nexusUsername, nexusPassword)))).
    map(_.asInstanceOf[coursier.Repository])
override def repositoriesTask = T { lnRepositories }

It complained about implicit parameter:

build.sc:29: could not find implicit value for parameter rw: upickle.default.ReadWriter[Seq[coursier.Repository]]
override def repositoriesTask = T { lnRepositories }

So then I added the implicit parameter definition (before the repositoriesTask):

implicit def rw: upickle.default.ReadWriter[Seq[coursier.Repository]] = upickle.default.macroRW

Now I am getting the following error:

build.sc:27: [error] The referenced trait [[Seq]] must be sealed.
implicit def rw: upickle.default.ReadWriter[Seq[coursier.Repository]] = upickle.default.macroRW

What is the solution for such problem?

[lefou]

It's probably because you used the T {} macros which is supposed to create a Target, whereas def repositoriesTask: Task[Seq[Repository[]] expects an anonymous Task. Just use the T.task {} macro, and you should be fine. No upickle reader-writer is needed.

[lilyevsky]

Thanks @lefou , that was the exact problem.