Introduction

The organization of type classes and functions in Scalaz 6 has a few weaknesses. Type classes that inherit from other type classes can lead to surprising results in implicit search; there isn't a way to implement an optimized version of derived functions (e.g. liftA2) for a given type; and the functionality provided by import scalaz._, Scalaz._ is hard to use on an a-la-carte basis.

We are trying out a few alternatives to improve this. You can see the scalaz7 branch for the first attempt, which removes type class inheritance, emphasises Monad transformers and isomorphisms between types. This led to a pchiusano/scalaz7-experimental and in turn [retronym/scalaz7-experimental/tree/inheritance-strikes-back retronym/scalaz7-experimental/tree/inheritance-strikes-back] which brings back type class inheritance (in a controlled manner), and moves a number of derived functions into the type classes.

While this redesign is in progress, release 6.x will be maintained.