wenduan writes:

The following function which converts a number represents a sum of money in pence didn't work as expected and the result didn't make any sense to me:

penceToString :: Price -> String penceToString p = let str = show p len = length str in if len ==1 then "0.0" ++ str else if len ==2 then "0." ++ str else (take (len-2) str) ++ "." ++ (drop (len - 2) str )

*Main> penceToString 234566666667899999999786 "-6710990.94"

You are encountering the fact the Int is a fixed size type (32 bits on many common architectures). Thus *Main> 234566666667899999999786 :: Int -671099094 Which explains the result. To make the program work use Integer instead of Int. - Einar Karttunen