Elm is easy to get started with. The learning curve is not too steep. Elm does not introduce an overwhelming amount of new concepts to understand and learn; actually, it is quite the opposite. Once you learn the Elm way of doing things, with the focus on some key concepts of functional programming, there is not a huge number of new topics to understand.

It can be a great way into the more advanced concepts of functional programming. It's probably among the easier ways to start thinking in terms of the functional programming paradigm.

Even though is it easy to learn, the return on investment is pretty high; imagine all the time you will save not having to do JavaScript-style debugging! In the long run, this ROI compounds. The way that Elm achieves this is by having no runtime errors. All the errors are caught at compile time (so you can forget about things like undefined is not a function on a live project). Compile time is very fast. Also, Elm has one of the friendliest and most helpful compilers around.

If you are a bit tired of JavaScript and want to look at alternatives, you will most likely love Elm. Along the same lines, if you have had trouble trying to make up your mind about whether you should learn Angular, or React, or Vue, or any other JS framework, Elm is a viable alternative.

If you are learning React, understanding the Elm architecture will help you wrap your mind around Redux. An interesting bit of trivia: Redux was inspired by the Elm architecture.

If you already have some experience with JavaScript, it will give you a new perspective on it, and actually make you a better JavaScript developer. You can even use Elm and JavaScript together! Elm interops with JavaScript so you can use both languages side by side in your projects.

Elm is declarative. Scaling your Elm apps is actually a pleasant experience. Elm has a great community and excellent documentation.

This book was written with the goal of introducing a complete beginner to the Elm language with some of its basic concepts and taking those concepts and building simple web apps in Elm from the get-go.

This book does not cover all the features of the Elm language, but rather gives you a solid foundation that you can build from.

One of the goals of this book was to make it easy for those who read it understand more advanced Elm apps and topics. Another goal of this book was to give you enough knowledge that you can confidently build your own apps in Elm once you complete it.

This book is intended for web developers of all levels of expertise to use to understand the Elm language and build simple and practical web applications in it.

The beauty of the Elm language, among other things, is in the fact that you don't need to worry too much about HTML and CSS when you write it. So in this book, the focus is mostly on the Elm language itself. 

Familiarity with HTML, CSS, and the DOM, as well as how the web works, would be helpful, but is not necessary. Also, some experience with the Bootstrap framework and Material Design Language is welcome, but not compulsory.

This book was written with the goal of finding a sweet spot between giving enough knowledge so that readers can be productive as soon as possible, and being overwhelming. 

The book was also written with the idea that someone who is brand new to web development should find it easy to understand. Therefore, the book doesn't assume knowledge of JavaScript, nor does it extensively compare JavaScript with Elm, or if it does, it tries to limit this comparison to the level of broad generalizations.

In a sentence, this book is aimed at beginners and experienced developers alike, regardless of their level of knowledge of JavaScript.

Chapter 1, Why Is This a Great Time to Learn Elm?, covers introductory topics: what is Elm, what is unique about it, how it compares to JavaScript, how to get started with it, and some very basic Elm concepts with simple code snippets.

Chapter 2, Building Your First Elm App, describes immutable data structures, the Elm architecture (model, view, and update), unidirectional data flows, using HTML functions in Elm, expressions in Elm (if-else and case expressions), Elm data structures, union types, and some operators.

Chapter 3, Creating Your Personal Portfolio with Elm, discusses type aliases, mapping and filtering values, adding Bootstrap 4 styles to your Elm apps, understanding function signatures, and modularizing your Elm apps.

Chapter 4, Preparing a Unit Conversion Website in Elm, looks at using the Result type as a way to handle errors, and reinforces concepts covered in the previous chapters in a fun project.

Chapter 5, Completing the Unit Conversion Website in Elm, explains using Html.map, working with complex views and multiple models, and shows how to improve the existing Unit Conversion website.

Chapter 6, Exploring Elm in Greater Detail, covers the topic of destructuring values in Elm, the ways in which Elm deals with randomness (through commands and subscriptions), understanding partial application, and working with Html.program.

Chapter 7, Making a Weather App in Elm, shows how to deal with errors using Result, how to deal with optional values and nothingness using Maybe, how to decode JSON strings, how to fetch remote data with the Http package, and how to work with third-party APIs.

Chapter 8, Adding More Features to the Weather App, shows how to make our Elm apps look nicer by adding elm-mdl and how to work with the Round module, and reinforces topics covered in previous chapters.

Chapter 9, Testing in Elm, covers Elm unit testing and the role of the describe, Expect.equals, and test functions; it also deals with some specific operators and ways to use them in Elm tests, how to write tests for decoding JSON, and introduces fuzz tests.

Chapter 10, Integrating Elm with a Web Framework, shows how to integrate Elm apps in Rails 5.1 using the Webpacker and Yarn, as well as set everything up in a web-based IDE using an Ubuntu container.

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