module Control.Exception.ErrorList (
ErrorList(..), EList(..),
throwError1, throwErrorC, addError1, addErrorC,
assert, assertC, wrapJust, withHandler, ifErrorDo, ifErrorReturn,
showError, showError', errorC, oneErrorC, firstSuccess,
inContext
) where
import qualified Prelude as P
import Prelude (($), (.), map, Int, Double, Functor(..), Show(..),
Eq(..), Bool(..), Integer, Double, Monad(..), flip,
Maybe(..), Either(..), IO(..))
import Control.Monad (liftM)
import Control.Monad.Trans (MonadIO(..), lift)
import Control.Monad.Except (ExceptT, MonadError(..), throwError, runExceptT)
import Control.Applicative hiding (empty)
import Data.Monoid
import Data.Text (Text, pack, unpack)
import qualified Data.Text as T
import qualified GHC.Exts as Exts
import Text.Render
class Exts.IsList elist => ErrorList elist where
addError :: Text -> elist -> elist
oneError :: Text -> elist
data EList = EList Text [Text] deriving (Show, Eq)
instance Exts.IsList EList where
type Item EList = Text
fromList (e:es) = EList e es
fromList _ = P.error "No main message in error list"
toList (EList msg msgs) = msg:msgs
instance ErrorList EList where
addError e (EList e' es) = EList e (e':es)
oneError e = EList e []
instance Render EList where
render (EList m msgs) = T.unlines $ "Error:" : map (sp <>) (m:msgs)
where sp = T.replicate 2 " "
throwError1 :: (ErrorList e, MonadError e m) => Text -> m a
throwError1 = throwError . oneError
throwErrorC :: (ErrorList e, MonadError e m) => [Text] -> m a
throwErrorC = throwError1 . mconcat
addError1 :: (ErrorList e, MonadError e m) => Text -> e -> m a
addError1 msg = throwError . addError msg
addErrorC :: (ErrorList e, MonadError e m) => [Text] -> e -> m a
addErrorC list = addError1 (mconcat list)
withHandler :: MonadError e m => (e -> m a) -> m a -> m a
withHandler = flip catchError
inContext :: (ErrorList e, MonadError e m) => Text -> m a -> m a
inContext ctx action = action `catchError` addError1 ctx
wrapJust :: MonadError e m => m a -> m (Maybe a)
wrapJust action = liftM Just action `ifErrorReturn` Nothing
ifErrorReturn :: MonadError e m => m a -> a -> m a
ifErrorReturn action a = action `ifErrorDo` return a
ifErrorDo :: MonadError e m => m a -> m a -> m a
ifErrorDo action action' = action `catchError` \_ -> action'
assert :: (ErrorList e, MonadError e m) => Bool -> Text -> m ()
assert True _ = return ()
assert False msg = throwError1 msg
assertC :: (ErrorList e, MonadError e m) => Bool -> [Text] -> m ()
assertC test = assert test . mconcat
showError :: (Render e, Render b) => (a -> Either e b) -> a -> IO ()
showError func arg = case func arg of
Left e -> P.putStrLn $ unpack $ render e
Right x -> P.putStrLn $ unpack $ render x
showError' :: (Render e, Render b) => (a -> (Either e b, c)) -> a -> IO ()
showError' func arg = case func arg of
(Left e, _) -> P.putStrLn $ unpack $ render e
(Right x, _) -> P.putStrLn $ unpack $ render x
errorC :: [Text] -> a
errorC = P.error . unpack . mconcat
firstSuccess :: (ErrorList e, MonadError e m) => Text -> [m a] -> m a
firstSuccess msg [] = throwError1 msg
firstSuccess msg (a:as) = a `ifErrorDo` firstSuccess msg as
oneErrorC :: ErrorList e => [Text] -> e
oneErrorC = oneError . mconcat