Control.Error.Context

Provides an API for enriching errors with contexts.

Documentation

data ErrorContext

Encapsulates the error context — essentially a stack of Text values.

Constructors

ErrorContext [Text]

Instances

Eq ErrorContext

Methods

(==) :: ErrorContext -> ErrorContext -> Bool

(/=) :: ErrorContext -> ErrorContext -> Bool

Show ErrorContext

Methods

showsPrec :: Int -> ErrorContext -> ShowS

show :: ErrorContext -> String

showList :: [ErrorContext] -> ShowS

data ErrorContextT m a

Data type implementing MonadErrorContext.

Instances

MonadTrans ErrorContextT

Methods

lift :: Monad m => m a -> ErrorContextT m a

MonadWriter w m => MonadWriter w (ErrorContextT m)

Methods

writer :: (a, w) -> ErrorContextT m a

tell :: w -> ErrorContextT m ()

listen :: ErrorContextT m a -> ErrorContextT m (a, w)

pass :: ErrorContextT m (a, w -> w) -> ErrorContextT m a

MonadState s m => MonadState s (ErrorContextT m)

Methods

get :: ErrorContextT m s

put :: s -> ErrorContextT m ()

state :: (s -> (a, s)) -> ErrorContextT m a

MonadReader r m => MonadReader r (ErrorContextT m)

Implement MonadReader for ErrorContextT.

Methods

ask :: ErrorContextT m r

local :: (r -> r) -> ErrorContextT m a -> ErrorContextT m a

reader :: (r -> a) -> ErrorContextT m a

Monad m => Monad (ErrorContextT m)

Methods

(>>=) :: ErrorContextT m a -> (a -> ErrorContextT m b) -> ErrorContextT m b

(>>) :: ErrorContextT m a -> ErrorContextT m b -> ErrorContextT m b

return :: a -> ErrorContextT m a

fail :: String -> ErrorContextT m a

Functor m => Functor (ErrorContextT m)

Methods

fmap :: (a -> b) -> ErrorContextT m a -> ErrorContextT m b

(<$) :: a -> ErrorContextT m b -> ErrorContextT m a

Applicative m => Applicative (ErrorContextT m)

Methods

pure :: a -> ErrorContextT m a

(<*>) :: ErrorContextT m (a -> b) -> ErrorContextT m a -> ErrorContextT m b

liftA2 :: (a -> b -> c) -> ErrorContextT m a -> ErrorContextT m b -> ErrorContextT m c

(*>) :: ErrorContextT m a -> ErrorContextT m b -> ErrorContextT m b

(<*) :: ErrorContextT m a -> ErrorContextT m b -> ErrorContextT m a

(MonadCatch m, MonadIO m) => MonadIO (ErrorContextT m)

Methods

liftIO :: IO a -> ErrorContextT m a

(MonadCatch m, MonadResource m) => MonadResource (ErrorContextT m)

Implement MonadResource for ErrorContextT.

Methods

liftResourceT :: ResourceT IO a -> ErrorContextT m a

MonadThrow m => MonadThrow (ErrorContextT m)

Implement MonadThrow for ErrorContextT.

Methods

throwM :: Exception e => e -> ErrorContextT m a

MonadCatch m => MonadCatch (ErrorContextT m)

Implement MonadCatch for ErrorContextT.

Methods

catch :: Exception e => ErrorContextT m a -> (e -> ErrorContextT m a) -> ErrorContextT m a

MonadThrow m => MonadErrorContext (ErrorContextT m)

Implement MonadErrorContext for ErrorContextT.

Methods

errorContextCollect :: ErrorContextT m ErrorContext

withErrorContext :: Text -> ErrorContextT m a -> ErrorContextT m a

class (Monad m, MonadThrow m) => MonadErrorContext m where

Monad type class providing contextualized errors.

Minimal complete definition

errorContextCollect, withErrorContext

Methods

errorContextCollect

Arguments

:: m ErrorContext

Return the current error context.

withErrorContext

Arguments

:: Text

-> m a

-> m a

Execute a monadic action while having the provided Text being pushed to the error context.

Instances

MonadThrow m => MonadErrorContext (ErrorContextT m)

Implement MonadErrorContext for ErrorContextT.

Methods

errorContextCollect :: ErrorContextT m ErrorContext

withErrorContext :: Text -> ErrorContextT m a -> ErrorContextT m a

data ErrorWithContext e

Boundles an error with an ErrorContext.

Constructors

ErrorWithContext ErrorContext e

Instances

Functor ErrorWithContext

Methods

fmap :: (a -> b) -> ErrorWithContext a -> ErrorWithContext b

(<$) :: a -> ErrorWithContext b -> ErrorWithContext a

Show e => Show (ErrorWithContext e)

Methods

showsPrec :: Int -> ErrorWithContext e -> ShowS

show :: ErrorWithContext e -> String

showList :: [ErrorWithContext e] -> ShowS

Exception e => Exception (ErrorWithContext e)

An ErrorWithContext e can be used as an exception.

Methods

toException :: ErrorWithContext e -> SomeException

fromException :: SomeException -> Maybe (ErrorWithContext e)

displayException :: ErrorWithContext e -> String

runErrorContextT :: ErrorContextT m a -> m a

Unwrap an ErrorContextT. Exceptions of type e thrown in the provided action via throwM will cause an ErrorWithContext e exception to be propagated upwards.

errorContextualize :: MonadErrorContext m => e -> m (ErrorWithContext e)

Enrich an error value with an error context.

errorContextForget :: ErrorWithContext e -> e

Forgets the context from an enriched error.

errorWithContextDump :: (Show e, MonadIO m) => ErrorWithContext e -> m ()

Dump an error with context to stdout.

catchWithoutContext :: forall a e m. (MonadCatch m, Exception e) => m a -> (e -> m a) -> m a

Like catch, but the handler is required to be context-unaware. Is also able to catch exceptions with context, in which case the context will be forgotten before the exception will be provided to the handler.

catchWithContext :: (MonadCatch m, Exception e) => m a -> (ErrorWithContext e -> m a) -> m a

Like catch, but the handler is required to be context-aware. Is also able to catch exceptions of type e (without context).

tryWithContext :: (MonadErrorContext m, MonadCatch m, Exception e) => m a -> m (Either (ErrorWithContext e) a)

tryAnyWithContext :: (MonadErrorContext m, MonadCatch m) => m a -> m (Either (ErrorWithContext SomeException) a)

catchJustWithContext :: (MonadCatch m, Exception e) => (e -> Maybe b) -> m a -> (b -> m a) -> m a

catchAnyWithContext :: MonadCatch m => m a -> (ErrorWithContext SomeException -> m a) -> m a

Context aware version of catchAny.

ensureExceptionContext :: (MonadCatch m, MonadErrorContext m) => m a -> m a