Hi The code in this chapter isn't actually Haskell - some details are elided to make the presentation clearer. To run the code you want to get the file mentioned in the closing remarks of the chapter (page 85, section 8.9). http://www.cs.nott.ac.uk/~gmh/book.html http://www.cs.nott.ac.uk/~gmh/parser.lhs Best wishes Stephen