18 data ClientSession = ClientSession
 19     { sec      :: Int
 20     , nsec     :: Int
 21     , username :: String
 22     , dbid     :: Integer
 23     , uuid     :: Int
 24     , prand    :: Int
 25     } deriving (Ord, Eq)
 26
 27 instance Show ClientSession where
 28     show (ClientSession
 29          { sec = s
 30          , nsec = ns
 31          , username = un
 32          , dbid = db
 33          , uuid = ud
 34          , prand = pr}) = intercalate "|" ls
 35         where ls = [show s, show ns, un, show db, show ud, show pr]

37 fromString :: String -> Maybe ClientSession
 38 fromString ss = fromParts $ endBy "|" ss
 ...
 74 fromParts :: [String] -> Maybe ClientSession
 75 fromParts (s:ns:un:db:ud:pr:[])
 76     = newSessionM (readMaybe s) (readMaybe ns) (Just un) (readMaybe db) (readMaybe ud) (readMaybe pr)
 77 fromParts _ = Nothing
 78
 79 newSessionM :: Maybe Int
 80             -> Maybe Int
 81             -> Maybe String
 82             -> Maybe Integer
 83             -> Maybe Int
 84             -> Maybe Int
 85             -> Maybe ClientSession
 86 newSessionM (Just s)
 87             (Just ns)
 88             (Just un)
 89             (Just db)
 90             (Just ud)
 91             (Just pr) = return $ newSession s ns un db ud pr
 92 newSessionM _ _ _ _ _ _ = Nothing
 93
 94 newSession :: Int -> Int -> String -> Integer -> Int -> Int -> ClientSession
 95 newSession s ns un db ud pr = ClientSession
 96     { sec = s
 97     , nsec = ns
 98     , username = un
 99     , dbid = db
100     , uuid = ud
101     , prand = pr}

import Control.Applicative
import Data.Char (isDigit)
import Data.Functor
import Data.List
import Text.ParserCombinators.ReadP as P

parseInt :: (Read a, Integral a) => ReadP a
parseInt = read <$> munch1 isDigit <* P.optional (char '|')

parseNotBar :: ReadP String
parseNotBar = munch (/= '|') <* P.optional (char '|')

instance Read ClientSession where
    readsPrec _ = readP_to_S parseClientSession
      where
        parseClientSession :: ReadP ClientSession
        parseClientSession =
            ClientSession <$> parseInt <*> parseInt <*> parseNotBar
                          <*> parseInt <*> parseInt <*> parseInt

instance Read ClientSession where
    readsPrec _ = readP_to_S $
            ClientSession <$> parseInt <*> parseInt <*> parseNotBar
                          <*> parseInt <*> parseInt <*> parseInt

newSessionM s ns un db ud pr
    = ClientSession <$> s <*> ns <*> un <*> db <*> ud <*> pr

parseClientSession =
    newSessionM parseInt parseInt parseNotBar
                parseInt parseInt parseInt