Expert F#

Expert F# does a great job explaining why and how you should use F#. It is not a general purpose tutorial on functional programming. The title "Expert" should be a hint that some (maybe... 25%?) of the topics are going to be advanced and move fast. If you're completely new to functional programming, Real World Haskell (already out) and Real World Functional Programming (Tomas Petricek, 2009) are good resources to get you in the right mindset. Regardless, this book covers the many aspects of F# and is the best general resource on F# so far.

As an experienced programmer, notably in C#, Scheme & Haskell, with no prior F# exposure, I've found Expert F# a joy to read and its level just right. The book reflects the language F# itself: it's elegant, fun & practical. Genuinely interesting, the code samples never appear contrived, as is usually the case in a text presenting a language. Actually, Expert F# goes well beyond teaching F#: it is a compelling demonstration of effective functional programming and I am sure I've grown as a programmer by reading it. It's also a book I've found myself coming back to, gaining new insights at each careful reading. My favorite chapter is Introducing Language-Oriented Programming (ch.9), which is packed with fascinating examples: probabilistic workflows, schema compilation by reflecting on types, and using F# quotations for error estimation (though see a correction to the math here: http://cs.hubfs.net/forums/5508/ShowThread.aspx), to name just the three most striking. In short, I enthusiastically recommend Expert F#, specially if your task requires you to program on the .NET platform. Though C# is OK, F# is more elegant, more fun & more productive -- you won't be looking back.

This book doesn't just teach you how to program in F#. I teaches you how to be a better .NET programmer. It discusses generics, how to write "generic algorithms," all forms of sequences (and how to elegantly program with them...immensely practical), workflows, LINQ, parsing (I loved this chapter), concurrent programming, Windows Forms...you get the idea. However, this book is *packed* with information. So, if you do get this book, and have difficulty...just try to write some code and re-read sections after you do some experimentation. You can't learn F# by reading about it. It is too elegant and subtle for that...you need to actually do it. So, read this book in your computer chair, not your easy chair, and TRY STUFF OUT...TAKE YOUR TIME ...there is a lot of information on each page. You'll be a better programmer in ANY language after going through this book.

When a new programming language arrives and manages to make an impact, books about it will certainly appear. However, most often the books will be geared to beginners, to people that is either not very experienced in programming or in the programming paradigms embodied by the language. For a experienced programmer, these books stop right when the fun would begin: the advanced stuff, the corners, the details are left out. Expert F#, as suggested by its title, is not like this: it is aimed at more experienced programmers. The book will not teach you, for instance, what is functional programming or hammer to your head the best ways to use lists, an ubiquitous data structure in functional languages. But it explains how the things work in F#, so that programmers already familiar with other functional languages will have no trouble picking it up. F# also has object-oriented capabilities, which are explained in a chapter, without however going much deep into OO concepts; the book is about the language, not the paradigms. And it does this well. Roughly half of the book is about the language itself, the other half are examples of applications and how to use some important libraries. As I was already familiar with OCaml and Haskell, I mostly skimmed through chapters 1 to 4, reading more closely starting with chapters 5 (generic types) and 6 (how objects fit into F#). From chapter 7 (encapsulating and packaging your code) on, the book starts to get really interesting; the next one is about common techniques, and chapter 9 is the best in the first part, explaining language-oriented programming, an area where functional languages really shine. There are mandatory chapters about Windows Forms (11), Web programming (14) using .NET and data access, including how to use LINQ in F#, but I really liked chapters 12 (working with symbolic representations), and 13 (concurrency and asynchronous workflows). The former includes two cool examples: a symbolic differentiator and a verifier for logic circuits based on BDDs (Binary Decision Diagrams). There are other important and advanced chapters treating topics like interoperation with C and COM, debugging and testing F# programs, and F# library design. All in all a very good book about the best current functional language to use in the Windows platform. I have two minor quibbles about it, though: the first few chapters about the language really could be made more interesting (although it didn't affect me much, as I only skimmed them) and some of the more exciting new features of F# could be explained in more detail. Specifically, workflows and active patterns. They are quite recent additions to the language, however, and there is some additional material promised to feature in the book's site. Anyway, I will keep this book nearby when programming in F#. It is this kind of book that you'd want to keep around, even after learning the language.