Reification doesn't just impose a substantial complexity cost on dynamic languages in the CLR, either. See this F# feature request from 2011 that is effectively

Reification doesn't just impose a substantial complexity cost on dynamic languages in the CLR, either. See this F# feature request from 2011 that is effectively unimplementable: https://visualstudio.uservoice.com/forums/121579-visual-studio-ide/suggestions/2228766-add-higher-order-generics-to-f-type-classes https://visualstudio.uservoice.com/forums/121579-visual-stud... As GP mentions, Haskell is a great example of achieving both superb type safety and superb type expression with type erasure. That said, sometimes you don't want superb type safety - things like dependency injection and mocks are examples of frameworks you can use in languages with some amount of type reification without restructuring your entire codebase. Java/JVM achieve a decent balance here imo.