import scala.language.experimental.namedTuples

object Test:
  val f: (name: String, age: Int) = ???
  val x: NamedTupleDecomposition.Names[f.type] = ("name", "age")

5 |  val x: NamedTupleDecomposition.Names[f.type] = ("name", "age")
  |                                                 ^^^^^^^^^^^^^^^
  |Found:    (String, String)
  |Required: NamedTupleDecomposition.Names[(Test.f : (name : String, age : Int))]
  |
  |Note: a match type could not be fully reduced:
  |
  |  trying to reduce  NamedTupleDecomposition.Names[(Test.f : (name : String, age : Int))]
  |  failed since selector (Test.f : (name : String, age : Int))
  |  does not match  case NamedTuple.NamedTuple[n, _] => n
  |  and cannot be shown to be disjoint from it either.

/** Separate from NamedTuple object so that we can match on the opaque type NamedTuple. */
@experimental
object NamedTupleDecomposition:
  import NamedTuple.*

  /** The names of a named tuple, represented as a tuple of literal string values. */
  type Names[X <: AnyNamedTuple] <: Tuple = X match
    case NamedTuple[n, _] => n