gistfile1.hs

{- 
-- If the task doesn't exist in the "db" it leaves AppState with the old state
setTaskStatus ::Int -> Bool ->  Update AppState Bool
setTaskStatus tid ns =do
  (AppState old) <- get
  case  (adjustTask tid (set_taskStatus ns) old) of
    [] -> return False
    xs -> do
      put (AppState xs)
      return True

setTaskDesc :: Int -> B.ByteString -> Update AppState Bool
setTaskDesc tid nd = do
  (AppState old) <- get
  case  (adjustTask tid ((set_taskDescr nd)) old) of
    [] -> return False
    xs -> do
      put (AppState xs)
      return True
-}
--Am I scrapping my boiler plate ? 

setTaskField :: Int  -> (Task -> Task )-> Update AppState Bool
setTaskField tid f = do
  s@(AppState old _) <- get
  case  (adjustTask tid f old) of
    [] -> return False
    xs -> do
      put (s { appdatastore = xs })
      return True

setTaskStatus ::Int -> Bool ->  Update AppState Bool
setTaskStatus tid ns = setTaskField tid (set_taskStatus ns)


setTaskDesc :: Int -> B.ByteString -> Update AppState Bool
setTaskDesc tid nd = setTaskField tid (set_taskDescr nd)


adjustTask :: Int -> (Task -> Task) -> [Task] ->[Task]
adjustTask tid f tl = let (h,xs) = break (\t -> tId t == tid) tl
                          in case xs of
                               r@x:xs' -> f x:h  ++ xs'
                               _ -> []