Foreword

A new language needs a simple and clear introductory book that makes it accessible to a broad range of programmers. In Foundations of F#, Robert Pickering has captured the essential elements that the professional programmer needs to master in order to get started with F# and .NET. As the designer of F#, I am thrilled to see Robert take up the challenge of presenting F# in a way that is accessible to a wide audience.

F# combines the simplicity and elegance of typed functional programming with the strengths of the .NET platform. Although typed functional programming is relatively new to many programmers and thus requires some learning, in many ways it makes programming simpler. This is mainly because F# programs tend to be built from compositional, correct foundational elements, and type inference makes programs shorter and clearer. Robert first introduces the three foundational paradigms of F#: functional programming, imperative programming, and object-oriented programming, and he shows how F# lets you use them in concert. He then shows how this multiparadigm approach can be used in conjunction with the .NET libraries to perform practical programming tasks such as GUI implementation, data access, and distributed programming. He then introduces some of the particular strengths of F# in the area of "language-oriented" programming.

F# is a practical language, and Robert has ensured that the reader is well equipped with information needed to use the current generation of F# tools well. Many computer professionals first encounter functional programming through a short section of the undergraduate curriculum and often leave these courses uncertain about the real-world applicability of the techniques they have been taught. Similarly, some people encounter functional programming only in its purest forms and are uncertain whether it is possible to combine the elements of the paradigm with other approaches to programming and software engineering. Robert has helped remove this uncertainty: typed functional programming is practical, easy to learn, and a powerful addition to the .NET programming landscape.

F# is also a research language, used in part to deliver recent advances in language design, particularly those that work well with .NET. It combines a stable and dependable base language with more recent extensions. Robert's book describes F# 2.0, the latest release of the language at the time of writing. The rest of the F# team and I are very grateful to Robert's many suggestions, and the language has been greatly improved through this. I hope you enjoy reading this book as much as I enjoyed being its technical reviewer.

Don Syme

Cambridge, UK