Tuple Trouble and Case Class Shenanigans: Scala's Wild World of Product Subtyping!Product subtyping in Scala allows for flexible relationships in tuples and case classes, mainly via weakening and substitution.
Bounded Quantification: Why Your Types Need Boundaries Even If You Don't!Universal quantifiers are contravariant as they must operate on all subtypes of a defined bound.Existential quantifiers are covariant since they represent the existence of some specific type within a bound.