Functional Programming Principles in Scala

Introduction

Typeclasses are a pattern that is widespread in functional programming libraries such as cats and cats-effect. In part one of this workshop we will explore how the mechanics of typeclasses work in Scala using the Monoid abstraction as an example. Then, in part two we will cover the patterns of composition defined by the Functor, Applicative and Monad typeclasses.

In this workshop we will be building everything from first principles. We will not be using any functional programming libraries and will only make minimal use of the scala standard library. By building these constructs from first principles you will understand at a fundamental level how they work, and when they should be applied.

After this workshop you should understand the mechanics of typeclasses, and the composition patterns expressed by Functor Applicative and Monad. This will allow you to effectively make use of similar abstractions libraries such as cats and provide the foundation to learn about other FP concepts independently.

The Workshop

All the details of the exercises, including reference to the relevant sections of provided code are linked below.

Part 1 – Covers the mechanics of typeclasses.

• Typeclasses

Part 2 – Covers Functor, Applicative and Monad

• Introduction
• Functor
• Applicative
• Monad
• Summary

Solutions – I strongly encourage you to try to solve all the exercises without referring to the solutions. If you are stuck, please ask a question. However, there are solutions to all the exercises in the solutions branch that you can refer to if needed.