Book Image

Learning Functional Programming in Go

By : Lex Sheehan
Book Image

Learning Functional Programming in Go

By: Lex Sheehan

Overview of this book

Lex Sheehan begins slowly, using easy-to-understand illustrations and working Go code to teach core functional programming (FP) principles such as referential transparency, laziness, recursion, currying, and chaining continuations. This book is a tutorial for programmers looking to learn FP and apply it to write better code. Lex guides readers from basic techniques to advanced topics in a logical, concise, and clear progression. The book is divided into four modules. The first module explains the functional style of programming: pure functional programming, manipulating collections, and using higher-order functions. In the second module, you will learn design patterns that you can use to build FP-style applications. In the next module, you will learn FP techniques that you can use to improve your API signatures, increase performance, and build better cloud-native applications. The last module covers Category Theory, Functors, Monoids, Monads, Type classes and Generics. By the end of the book, you will be adept at building applications the FP way.
Table of Contents (21 chapters)
Title Page
Credits
About the Author
Acknowledgments
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

The Lambda Calculus


Lambda calculus is a logical system of rules for expressing computation using variable binding, abstraction, and function application. We can define anonymous functions and apply those functions. Lambda calculus would be limited if it weren't for recursion. Pure functional programming languages derived from lambda calculus include LISP, Haskell, and ML.

Lambda Expressions

A lambda expression is an instance of a functional interface consisting of a set of terms. These terms can be variables like x, y, and z. These are not mutating variables, but rather placeholders for values or other lambda terms. The variable inside of x is applied to whatever it is bound to. The variable x is inside the term t. The lambda abstraction is defined as λ x.t.

For example, if we have the equation f(x) = x2 and replace x with 5, we have f(5) =  52.

When the function f is applied to x, we get x2. In our example, the function f is applied to the argument 5 and we get 52.

We can eliminate the parentheses...