Conventions used

There are a number of text conventions used throughout this book.

Code in text: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: “The type signature states that the function has the name increment and, given a value of the Int type as input, produces a result of the Int type.”

A block of code is set as follows:

redSuits :: [Suit]
redSuits = Hearts : Diamonds : []

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

data Expr = Lit Int | Add Expr Expr

Any function call is written as follows:

*Main> renderExpr (Add (Lit 2) (Lit 5))
“2+5”

Bold: Indicates a new term, an important word, or words that you see on screen. For instance, words in menus or dialog boxes appear in bold. Here is an example: “What sets FP apart from the other two is that it is a member of the declarative programming family.”