Professor Frisby's Mostly Adequate Guide to Functional Programming

Book Details

Author	Brian Lonsdorf
Published	2024
Edition	1st
Paperback	151 pages
Language	English
License	Creative Commons Attribution-ShareAlike

Book Description

This is a book on the functional paradigm in general. Brian Lonsdorf will use the world's most popular functional programming language: JavaScript. He acknowledges that some may feel this is a poor choice as it's against the grain of the current culture which, at the moment, feels predominately imperative. However, Lonsdorf believes it is the best way to learn FP for several reasons:

He notes that readers likely use JavaScript every day at work, making it possible to practice and apply acquired knowledge each day on real world programs rather than on pet projects in an esoteric FP language.

Lonsdorf points out that with JavaScript, one doesn't have to learn everything up front to start writing programs, noting that in a pure functional language, you cannot log a variable or read a DOM node without using monads. He explains that with JavaScript, learners can cheat a little as they learn to purify their codebase, and that it's easier to get started since it's a mixed paradigm language, allowing readers to fall back on their current practices while there are gaps in their knowledge.

The author asserts that the language is fully capable of writing top-notch functional code, having all the features needed to mimic a language like Scala or Haskell with the help of a tiny library or two. Lonsdorf observes that while object-oriented programming currently dominates the industry, it's clearly awkward in JavaScript, which he describes as being "akin to camping off of a highway or tap dancing in galoshes." He notes various challenges with OOP in JavaScript and suggests that to a lot of people, FP feels more natural anyway.

Lonsdorf states that typed functional languages will, without a doubt, be the best place to code in the style presented by this book. He positions JavaScript as a means of learning a paradigm, while leaving where readers apply it up to them. The author notes that luckily, the interfaces are mathematical and, as such, ubiquitous, suggesting readers will find themselves at home with Swiftz, Scalaz, Haskell, PureScript, and other mathematically inclined environments.

This book is available under a Creative Commons Attribution-ShareAlike license (CC BY-SA), which means that you are free to copy, distribute, and modify it, as long as you credit the original author and license any derivative works under the same terms.