Death to Type Classes: Exploring the Backpack Module System in Haskell
2025-09-15
This article explores replacing type classes with the Backpack module system in Haskell. The author demonstrates, through an example called "Death," how to define signatures for types like Functor and implement different instances (e.g., Maybe and IO). Cabal configuration allows flexible selection of implementations, such as using a state monad to simulate IO during testing. This approach, while requiring more Cabal configuration, offers clearer error messages, more flexible control, and potential performance advantages. The article concludes with a minimalist programming philosophy, arguing that simplification leads to better readability and maintainability.
Development
Module System