Preface
For the last two years, interest in F# and functional-first programming has been growing steadily. More than 10 books about F# are now on the market, more than one new user group has appeared somewhere in the world every month during the last year, and the number of members of and visitors to the F# Software Foundation has been increasing at a steady rate.
Many people become interested in F# because they hear about the benefits that functional-first programming gives you: the F# type system mostly removes the need for null checking and other invalid states; avoiding a mutable state and its declarative nature makes it easier to understand your programs; and the agent-based programming model simplifies concurrency. These are all nice facts ...