Replacing case class inheritance with extractors preserving exhaustiveness checks in Scala

Question

I have a simple class hierarchy that represents a graph-like structure with several distinct types of vertexes implemented using case classes:

sealed trait N         


        

Answer 1

The citation from scala-lang.org:

If the selector of a pattern match is an instance of a sealed class, the compilation of pattern matching can emit warnings which diagnose that a given set of patterns is not exhaustive, i.e. that there is a possibility of a MatchErrorbeing raised at run-time.