Book Image

Mastering Functional Programming

Book Image

Mastering Functional Programming

Overview of this book

Functional programming is a paradigm specifically designed to deal with the complexity of software development in large projects. It helps developers to keep track of the interdependencies in the code base and changes in its state in runtime. Mastering Functional Programming provides detailed coverage of how to apply the right abstractions to reduce code complexity, so that it is easy to read and understand. Complete with explanations of essential concepts, practical examples, and self-assessment questions, the book begins by covering the basics such as what lambdas are and how to write declarative code with the help of functions. It then moves on to concepts such as pure functions and type classes, the problems they aim to solve, and how to use them in real-world scenarios. You’ll also explore some of the more advanced patterns in the world of functional programming such as monad transformers and Tagless Final. In the concluding chapters, you’ll be introduced to the actor model, which you can implement in modern functional languages, and delve into parallel programming. By the end of the book, you will be able to apply the concepts of functional programming and object-oriented programming (OOP)in order to build robust applications.
Table of Contents (17 chapters)

Understanding lambda functions

Most functional languages have a concept of a lambda function. It is an anonymous function defined inline. It can be assigned to a variable if needed. For example, consider that we need a function that accepts a cookie with user session data, in the context of a web application. Its job is to print a greeting to the user to the standard output. However, before printing, we need to decorate the user's name in a certain way. To complicate matters further, we also have a database of users who hold PhDs and, if they do, we need to refer to them as Dr. Here is how it can be done in Scala:

  1. We define the dummy Cookie class for our example:
case class Cookie(name: String, gender: String)
  1. We define the greeting method. The job of the method is to extract the data from the cookie object, and apply the modifier to the user's name based on their...