Hi there Jack, I have modified your program. However, where you were attempting to use direct recursion to compute totalSales, I have used functions from the prelude. I have also provided a recursive definition totalSalesRec. Here is a lesson on recursion from the Haskell wikibook http://en.wikibooks.org/wiki/Haskell/Recursion Also, what you have is an associative array which pairs (Artist, Title) with Sold. A linked list [(Artist, Title, Sold)] is an inappropriate data type for this purpose. Consider using Map from Data.Map in the form Map (Artist, Title) Sold. I have included comments which I hope you will find useful in understanding the code. Also note my use of comments like: -- | This is a function that does blah These are annotations for the Haskell documention generator, Haddock http://www.haskell.org/haddock/ What I'd do to run haddock on this file (I use linux and I have saved as artist.hs) is mkdir doc && haddock artist.hs -o doc -h Now you can look at documentation for your program in a web browser while fickering with it in GHCi. Be aware that my copy pasting this file onto here may well have mangled its syntax! Have fun, Johnny module Main (main ,testDatabase ,totalSales ,totalSalesRec ,printNames ,mainLoop) where -- | Title of a record type Title = String -- | An artist, who makes records type Artist = String -- | Number of copies of a record sold type Sold = Int type Sales = [(Title, Artist, Sold)] -- | A small sales database testDatabase :: Sales testDatabase = [("Kids", "MGMT", 3), ("This Charming Man", "The Smiths", 5), ("Gimme Shelter", "The Rolling Stones", 7)] -- Notice there are no explicit function arguments here. Look up 'partial application'. -- | Total sales of all records in the database. totalSales :: Sales -> Sold totalSales = -- The sum of all the sales sum . map sale where sale (_,_,s) = s -- | Recursive version of totalSales totalSalesRec :: Sales -> Sold totalSalesRec ((_,_,s):ss) = s + totalSalesRec ss totalSalesRec _ = 0 -- | Print out the contents of a sales database printNames :: Sales -> IO () printNames testDatabase = mapM_ print testDatabase -- Main application loop mainLoop :: Sales -> IO () mainLoop testDatabase = do putStrLn "1 - Show all tracks in database" putStrLn "2 - Show the total sales" putStrLn "3 - Add a new entry" putStrLn "4 - Exit" putStrLn "" putStrLn "Please select an option:" input <- getLine case read input of 1 -> do banner "Show All Tracks" printNames testDatabase putStrLn "" mainLoop testDatabase 2 -> do banner "Total Sales" print $ totalSales testDatabase putStrLn "" mainLoop testDatabase 3 -> do banner "New entry" putStrLn "Enter artist name" a <- getLine putStrLn "" putStrLn "Enter title" t <- getLine putStrLn "" putStrLn "Enter number of sales" -- Look up functors to understand fmap s <- fmap read getLine putStrLn "" -- 'cons' the new element to the start of the linked list testDatabase -- Look up data constructors. mainLoop $ (a,t,s) : testDatabase -- No 'do' is required for only one statement. Look up monads and how 'do' is syntactic sugar. 4 -> return () where -- Print banner banner s = do putStrLn "------------------" putStrLn s putStrLn "------------------" -- | Run main :: IO () main = mainLoop testDatabase