Hi, applebiz89 wrote:
data Film = Film String String Int String
with this as the data.
testDatabase :: [Film] testDatabase = [("Casino Royale", "Martin Campbell",2006, "Garry, Dave, Zoe")]
Try to compile this part of the program, to get a feeling for whether you are on the right track. If it does not compile, try to find out what's wrong and correct it so that it compiles. As you already noted in a different mail, you plan to change the representation of the list of fans to a list of strings (instead of a single string with commas). That is a good idea! So change the data declaration, and change the definition of testDatabase to this new design. Try to compile that program. Now you can add some utility functions to work with your database. This will make it much easier to write a correct user interface later. For example, write a function isFan :: [Film] -> String -> String -> Bool which checks whether someone is a fan of a film in your database. In other words, isFan testDatabase "Garry" "Casino Royale" should be True, but isFan testDatabase "Peter" "Matrix" should be False. Another useful utility function could be becomeFan :: String -> String -> [Film] -> [Film] which adds the information that someone is a fan of some film to an existing database. Note that this function does not do any user interaction, but gets the name of the fan and the name of the film as arguments. Think about which other utility functions you could use. Try them out in ghci. When you have done that, you can write a user interface which asks for input on the command line and uses the utility functions to keep track of the current database. Tillmann