postgrest/docs/Exceptions.md

Exceptions

MonadError

class Monad m => MonadError e (m :: * -> *) | m -> e where
  throwError :: e -> m a
  catchError :: m a -> (e -> m a) -> m a

Except

type Except e = ExceptT e Identity

Example:

ExceptT

newtype ExceptT e (m :: * -> *) a
  = Control.Monad.Trans.Except.ExceptT (m (Either e a))

Example:

throwError

throwError :: MonadError e m => e -> m a

catchError

catchError :: MonadError e m => m a -> (e -> m a) -> m a

runExcept

runExcept :: Except e a -> Either e a

runExceptT

runExceptT :: ExceptT e m a -> m (Either e a)

Exceptions

class (Typeable e, Show e) => Exception e where
  toException :: e -> SomeException
  fromException :: SomeException -> Maybe e
  GHC.Exception.displayException :: e -> String

throwIO

throwIO :: (MonadIO m, Exception e) => e -> m a

throwSTM

throwSTM :: Exception e => e -> STM a

throwTo

throwTo :: (MonadIO m, Exception e) => ThreadId -> e -> m ()

Utilities

hush

hush :: Alternative m => Either e a -> m a

note

note :: (MonadError e m, Applicative m) => e -> Maybe a -> m a

tryIO

tryIO :: MonadIO m => IO a -> ExceptT IOException m a

Fatal Errors

data FatalError = FatalError {fatalErrorMessage :: Text}

panic

panic :: Text -> a

Terminate with an uncatchable fatal error.

> panic "Fatal error occured.