| Safe Haskell | Safe-Inferred |
|---|---|
| Language | Haskell2010 |
Control.Monad.Error.Hoist
- class Monad m => HoistError m t e e' | t -> e where
- hoistError :: (e -> e') -> t α -> m α
- (<%?>) :: HoistError m t e e' => t α -> (e -> e') -> m α
- (<%!?>) :: HoistError m t e e' => m (t α) -> (e -> e') -> m α
- (<?>) :: HoistError m t e e' => t α -> e' -> m α
- (<!?>) :: HoistError m t e e' => m (t α) -> e' -> m α
Documentation
class Monad m => HoistError m t e e' | t -> e where Source
A tricky class for easily hoisting errors out of partiality types (e.g.
Maybe, Either ee represents the error
information carried by the partiality type t, and e' represents the type
of error expected in the monad m.
Methods
hoistError :: (e -> e') -> t α -> m α Source
Given a conversion from the error in t α to e', we can hoist the
computation into m.
Instances
| MonadError e m => HoistError m Maybe () e | |
| MonadError e' m => HoistError m (Either e) e e' |
(<%?>) :: HoistError m t e e' => t α -> (e -> e') -> m α infixr 9 Source
A flipped synonym for hoistError.
(<%!?>) :: HoistError m t e e' => m (t α) -> (e -> e') -> m α infixr 9 Source
A version of <%?> that operates on values already in the monad.
(<?>) :: HoistError m t e e' => t α -> e' -> m α infixr 9 Source
A version of hoistError that ignores the error in t α and replaces it
with a new one in e'.
(<!?>) :: HoistError m t e e' => m (t α) -> e' -> m α infixr 9 Source
A version of ? that operates on values already in the monad.