Hey thanks, that was really helpful actually. I know it must be annoying for you, and im sorry but ive done what you said, try and compile it to see if it does and fix it. I have tried every possible way of using brackets in different place's etc (as u can tell Im not good with haskell at all) but it still isnt, it must be to do with my data type. -- Film as datatype data Film = String String Int [String] -- List of films testDatabase :: [Film] testDatabase = ["Casino Royale", "Martin Campbell" ,2006, ["Garry", "Dave", "Zoe"] ] I get this error: *** Expression : ["Casino Royale","Martin Campbell",2006,[("Garry","Dave","Zoe")]] *** Term : [("Garry","Dave","Zoe")] *** Type : [([Char],[Char],[Char])] *** Does not match : [Char] Thanks alot! applebiz Tillmann Rendel-3 wrote:
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 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
-- View this message in context: http://www.nabble.com/Getting-started---help-tp23314466p23318195.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.