scala generic function `not found: type ?`

Question

When I use scala to create a function like this,It told me that not found: type ?

scala
    def save[
      K: SpatialComponent: TypeTag,
      V <: CellGrid: TypeTag: ? => TileMergeMethods[V]: ? => TilePrototypeMethods[V]
      ](id: LayerId, rdd: RDD[(K, V)] with Metadata[TileLayerMetadata[K]], method: KeyIndexMethod[K])

Can somebody told me how to resolve this?

The first-level answer is because you're using `?` as a type and it's not defined. The real question is what you were intending by doing that? — The Archetypal Paul, Jun 20 '16 at 06:27

score 2 · Accepted Answer · answered Jun 20 '16 at 07:38

2

I got it,must add this code to build.sbt.

resolvers += Resolver.sonatypeRepo("releases")
addCompilerPlugin("org.spire-math" % "kind-projector" % "0.8.0" cross CrossVersion.binary)

https://github.com/non/kind-projector

answered Jun 20 '16 at 07:38

wsf1990

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scala generic function `not found: type ?`

1 Answers1