The third edition of one of the leading textbooks for beginning functional programmers is thoroughly revised throughout. Revisions include new material on testing and domain-specific languages and a variety of new examples and case studies, including simple games.

Existing material has been expanded and re-ordered, so that some concepts - such as simple data types and input/output - are presented at an earlier stage. The running example of Pictures is now implemented using web browser graphics as well as lists of strings.

The book uses the GHCi, interactive version of the Glasgow Haskell Compiler, as its implementation of choice. It has also been revised to include material about the Haskell Platform, and the Hackage online database of Haskell libraries. In particular, readers are given detailed guidance about how to find their way around what is available in these systems.