Preface: The Story of the Book

In 2003 I was looking for a way to process IL, the intermediate language into which all .NET languages are compiled. At the time, .NET was fairly new, and there weren't a lot of options for doing this. I quickly realized that the best option at the time, and probably still today, was an API called Abstract IL (AbsIL). AbsIL was written in a language called F#, and I decided to use this language to write a small wrapper around AbsIL so I could extract the information I needed from a DLL in a form more usable from C#. But a funny thing happened while writing the wrapper: even though in those days writing F# was a little hard going because the compiler was far from polished, I found that I actually enjoyed programming in F# so much that when I had finished the wrapper, I didn't want to go back to C#. In short, I was hooked.

At the time I was working as a consultant, so I needed to regularly check out new technologies and their APIs; therefore, I got to do all my experimentation using F#. At the same time, people were talking about a new way to communicate on the Web, and a new word was about to enter the English language: blog. I decided I should have a blog because anyone who was anyone in technology seemed to have one, so I created http://www.strangelights.com (where my blog can still be found to this today). This was later followed by a wiki about F#, which can also be found at http://www.strangelights.com and which continues to be very popular.

My job meant I had to do a lot of traveling, so this meant quite a lot of time in hotel rooms or on trains and planes, and I came to view this time as time to try out stuff in F#. So, I ended up exchanging quite a lot emails with Don Syme, and then eventually we met. We went for a beer in the pub where Watson and Crick went after they first pieced together the structure of DNA. Will people talk about the pub were Syme and Pickering first met years from now? Errrm, perhaps not. Anyway, all this led me to the point where I was wondering what I should do with my newfound knowledge of F# and functional programming. About this time a guy called Jim Huddleston mailed the F# mailing list and asked whether anyone would like to write a book about F#. Well, I just couldn't help myself—it sounded like the job for me.

So, with much help and encouragement from Jim, I started writing the book. Some of it was written in Paris where I was living on the weekends, some of it was written in Brussels were I was working during the week, and much of it was written while I was traveling between the two on the Thalys (the high-speed train between France and Belgium). A little of it was written as far north as the Orkney Islands in Scotland while visiting my aunt and uncle, and a little of the reviewing was done while meeting my in-laws in New Zealand. Finally, thanks to the contacts I made while writing the book, I got a new job working for the prestigious ISV LexiFi.

It has been great fun watching the language evolve over time and turn from the beginnings of a language into the fully fledged and highly usable language you see today. I hope reading this book changes your life as much as writing it has changed mine.