15 10 2016
I was recently exploring shapeless and a coworker turned me onto the interesting features of coproducts and how they can be used with polymorphic functions.
Frequently when using pattern matching you want to make sure that all cases are exhaustively checked. A non exhaustive pattern match is a runtime exception waiting to happen. As a scala user, I’m all about compile time checking. For classes that I own I can enforce exhaustiveness by creating a sealed trait heirarchy:
sealed trait Base case class Sub1() extends Base case class Sub2() extends Base
And if I ever try and match on an
Base type I’ll get a compiler warning (that I can fail on) if all the types aren’t matched. This is nice because if I ever add another type, I’ll get a (hopefully) failed build.
But what about the scenario where you don’t own the types?
case class Type1() case class… Read more