Modern FP using Tagless Final

For quite some time there is a new way of app composition, superceding Free Monads, gaining popularity in the FP community. It allows to define the accurate description of the components' work without overhead charges and is a perfect realization of Dependency Inversion Principle.

As for the Scala, this approach fits amazingly well into the language's syntax.

We'll discuss the history and the formal, technical and practical aspects of implementing this approach using Scala as an example.