package preface

A Free selective allows you to build a rigid Preface_specs.Selective from a given Preface_specs.Functor.

Such Preface_specs.selective is equipped with and additional function for promoting values from the underlying Preface_specs.Functor into the Free selective and a Natural transformations for transforming the value of the Free selective to an other Preface_specs.Selective or to a Preface_specs.Monoid.

Note about complexity

Although free constructs are elegant, they introduce an execution cost due to the recursive nature of defining the type of a Free Selective. There are cheaper encodings but they are not, for the moment, available in Preface.

Structure anatomy

Complete API

Additional references

• Haskell's documentation of a Selective Application Functor
• Selective Applicative Functors