Hi Haskellers, This is a style question, as my program works fine but looks really ugly and can be confusing to maintain. I take options from the command line using GetOpt and hand back this structure for later use.
data Opts = Opts { query :: Query , queryLimit :: Maybe Limit , disabledOnly :: Bool } deriving Show
Here's a snippet from the parser for one option (others omitted for clarity):
options :: [OptDescr (Opts -> Opts)] options = [ Option "b" ["bus"] (ReqArg busNum "NUM") "Bus number" , ... ] where busNum n os = let b = (query os) { queryBusNumber = Just n } in if isBusId n then os { query = b } else os
Variations on that ugliness are repeated four times for other fields. Is there an alternative way to change the value of nested fields? Thanks, Dougal. -- Dougal Stanton dougal@dougalstanton.net // http://www.dougalstanton.net