Preface

Writing good software is hard. After years of struggling with other approaches, both of us discovered and fell in love with functional programming (FP). Though the FP approach is different, we came to appreciate how the discipline leads to a coherent, composable, and beautiful way of writing programs.

Both of us participated in the Boston Area Scala Enthusiasts, a group that met regularly in Cambridge. When the group first started, it mainly consisted of Java programmers who were looking for something better. Many expressed frustration that there wasn’t a clear way to learn how to take advantage of FP in Scala. We could empathize—we had both learned FP somewhat haphazardly, by writing lots of functional code, talking to and learning from other Scala and Haskell programmers, and reading a patchwork of different articles, blog posts, and books. It felt like there should be an easier way. In April 2010 one of the group’s organizers, Nermin Šerifović, suggested that we write a book specifically on the topic of FP in Scala. Based on our learning experiences, we had a clear idea of the kind of book we wanted to write, and we thought it would be quick and easy. More than four years later, we think we have created a good book. It’s the book we wish had existed when we were learning functional programming.

We hope to convey in this book some of the excitement that we felt when we were first discovering FP.