Isaac Abraham - Get Programming With F#

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When I first met Isaac Abraham in 2015, I knew immediately that he shared my passion for educating .NET developers in the art of F#. His book, which you hold in your hands, is the text I had wanted when I first kindled my F# romance. Inside, Isaac will lead you on a journey of F# thats both pragmatic and relevant. If youre a C# or Visual Basic .NET developer, youll learn through a series of lessons how to apply F# to everyday .NET development. You wont have to wade through the deep theoretical explanations that are often the staple of functional programming books. Instead, Isaac will guide you with practical advice and best practices derived from his own experience as an F# developer.

I first fell in love with F# when it was still a research language being developed out of Microsoft Research in Cambridge, England. The language was a bit rough around the edges, but every monthly release brought a fresh set of exciting new features to explore. The community was small but already vibrant, eager to evangelize any who would listen about how F# was so expressive, powerful, and fun. I found myself caught up in it all.

Since F# was still very new, there werent many books available to help me learn the language. Being a self-taught C# programmer, I wanted something that was light on theory and heavy on practice, but such books hadnt been written yet. I even made my own meager attempt to fill that void, by writing a blog series (viewable today only via the Internet Archive) titled, Why I Love F#.

In each blog article, I attempted to present F# to everyday C# developers like myself, highlighting features that marry well with .NET development such as the F# Interactive environment, type-safe format strings, tuples, and pattern matching. I wanted to encourage others to explore this beautiful language that Id become quite smitten with, and to teach them how to use it effectively to create .NET programs. Eventually, my blog fell by the wayside. After joining the .NET languages team at Microsoft, I could no longer find the time to keep it current and gave it up.

Fast-forward to today. Today, F# is more popular than ever and growing at a rapid pace. F# code is running quite literally everywhere: on desktops, mobile devices, the web, IoT devices, and in the cloud. F# has reached its fourth major version, boasts an active and fiercely passionate community, and enjoys first-class tooling support in many IDEs and editors, such as Visual Studio, Visual Studio for Mac, and JetBrains Rider. And of course, F# books are available on a wide variety of topics, from the more general purpose to fully scientific.

F# exemplifies an aspect of programming that all too often is forgotten: programming should be fun. With Isaac as your teacher, Im confident youll have an absolute blast.

D USTIN C AMPBELL P RINCIPAL S OFTWARE E NGINEER , .NET L ANGUAGES T EAM , M ICROSOFT

In the Introduction to F#, Isaac mentions that F# leads you to a pit of success, which is something that I wholeheartedly agree with. I believe that the way this happens has a lot to do with how a pragmatic way of thinking, functional ideas, and a powerful runtime come together in F#. The functional ideas serve as a fantastic tool for understanding and modeling the problem domain in a simple way. At the same time, F# gives you a versatile toolbox for solving concrete problems within the domain. This includes a language that supports multiple paradigms including functional, object-oriented, and imperative, but also powerful .NET and F# libraries. Again, this book introduces F# from exactly the right perspective. It rightly puts a strong emphasis on thinking about the domain in a functional way, but at the same time, it introduces all of the important tools from the F# toolbox.

When I started learning the F# language 10 years ago, the typical advice was that F# is just a functional programming language for .NET, so you should forget everything you know about programming, read a couple of academic functional programming textbooks, and then figure out how to use the functional concepts to write .NET applications on your own.

Im happy that this isnt the advice we give to people who are curious about F# these days. There are two main reasons for this. First, it turns out that forgetting everything is just a poor strategy for learning F# if you have existing programming knowledge. Second, it also turns out that the functional programming label is only partly appropriate for the kind of code you write when using F# to solve real-world problems. This book reflects both points, which is what makes it a fantastic material for learning F#.

The difference between F# and other .NET languages is equally easy to overstate and to understate. On one hand, many functional language constructs now exist in C# and VB .NET, so you might think that the difference isnt that big. On the other hand, F# is rooted in functional programming and leads you to different way of thinking about problems, so you might think that you need to start from a clean slate. As is often the case, the truth is somewhere in the middle. When using F#, youll find yourself designing software differently and, as a result, falling into the pit of success described in unit 5. At the same time, learning F# shouldnt be as daunting as it was 10 years ago. Youll find many similarities to what you know already, and this book does a great job of using them to explain F# clearly and effectively.

If youre a C# or VB .NET developer who cares about solving problems in a pragmatic way, this is the book for you. Theres no need to wait for the right problem that will be well suited to functional programming and give you an excuse to learn F#. As this book clearly explains, the point of F# isnt just in functional programming, but in the pit of success, where the F# way of solving problems leads you.