Overloading methods based on generics - scala

Question

I'd like to overload a method based on generics - so something like this:
case class Indexed2dArr[Dim0Type, Dim1Type] (
indices: (List[Dim0Type], List[Dim1Type]),
array: List[List[Float]],
) {
def getSliceAtIndexLocation(i: Dim0Type): (List[Dim1Type], List[Float]) = ???
def getSliceAtIndexLocation(i: Dim1Type): (List[Dim0Type], List[Float]) = ???
}
So if getSliceAtIndexLocation is called with a parameter of Dim0Type, it returns a single-dimensioned slice of the orginal array, with an index of Dim1Type. And vice-versa for calling with Dim1Type.
This raises a double definition compiler error - that the two methods have the same type after type erasure, this type being (i: Object): Tuple2. Is there a valid way to wrangle this or is it straight-up impossible?

Answer 1

Try either DummyImplicit
case class Indexed2dArr[Dim0Type, Dim1Type] (
indices: (List[Dim0Type], List[Dim1Type]),
array: List[List[Float]],
) {
def getSliceAtIndexLocation(i: Dim0Type): (List[Dim1Type], List[Float]) = ???
def getSliceAtIndexLocation(i: Dim1Type)(implicit
di: DummyImplicit): (List[Dim0Type], List[Float]) = ???
}
or type class pattern
case class Indexed2dArr[Dim0Type, Dim1Type] (
indices: (List[Dim0Type], List[Dim1Type]),
array: List[List[Float]],
) {
def getSliceAtIndexLocation[A](i: A)(implicit tc: TC[A]): tc.Out = tc(i)
trait TC[A] {
type B
type Out = TC.MkOut[B]
def apply(i: A): Out
}
object TC {
type MkOut[B] = (List[B], List[Float])
type Aux[A, B0] = TC[A] { type B = B0 }
def instance[A, B0](f: A => MkOut[B0]): Aux[A, B0] = new TC[A] {
override type B = B0
override def apply(i: A): Out = f(i)
}
implicit val dim0Type: Aux[Dim0Type, Dim1Type] = instance(i => ???)
implicit val dim1Type: Aux[Dim1Type, Dim0Type] = instance(i => ???)
}
}
or magnet pattern
import scala.language.implicitConversions
case class Indexed2dArr[Dim0Type, Dim1Type] (
indices: (List[Dim0Type], List[Dim1Type]),
array: List[List[Float]],
) {
def getSliceAtIndexLocation(m: Magnet): m.Out = m()
trait Magnet {
type B
type Out = Magnet.MkOut[B]
def apply(): Out
}
object Magnet {
type MkOut[B] = (List[B], List[Float])
type Aux[B0] = Magnet { type B = B0 }
def instance[B0](x: MkOut[B0]): Aux[B0] = new Magnet {
override type B = B0
override def apply(): Out = x
}
implicit def dim0Type(i: Dim0Type): Aux[Dim1Type] = instance(???)
implicit def dim1Type(i: Dim1Type): Aux[Dim0Type] = instance(???)
}
}