Control.Monad.Validate.Class

Documentation

class (Monad m, Semigroup e) => MonadValidate e m | m -> e where

The class of validation monads, intended to be used to validate data structures while collecting errors along the way. In a sense, MonadValidate is like a combination of MonadError and MonadWriter, but it isn’t entirely like either. The two essential differences are:

1. Unlike throwError, raising an error using refute does not always abort the entire computation—it may only abort a local part of it.
2. Unlike tell, raising an error using dispute still causes the computation to globally fail, it just doesn’t affect local execution.

For a more thorough explanation, with examples, see the documentation for ValidateT.

Minimal complete definition

Nothing

Methods

refute :: e -> m a

Raises a fatal validation error. Aborts the current branch of the validation (i.e. does not return).

dispute :: e -> m ()

Raises a non-fatal validation error. The overall validation fails, and the error is recorded, but validation continues in an attempt to try and discover more errors.

refute :: (MonadTrans t, MonadValidate e m', m ~ t m') => e -> m a

Raises a fatal validation error. Aborts the current branch of the validation (i.e. does not return).

dispute :: (MonadTrans t, MonadValidate e m', m ~ t m') => e -> m ()

Raises a non-fatal validation error. The overall validation fails, and the error is recorded, but validation continues in an attempt to try and discover more errors.

Instances

MonadValidate e m => MonadValidate e (MaybeT m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> MaybeT m a

dispute :: e -> MaybeT m ()

(MonadValidate e m, Monoid w) => MonadValidate e (WriterT w m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> WriterT w m a

dispute :: e -> WriterT w m ()

(MonadValidate e m, Monoid w) => MonadValidate e (WriterT w m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> WriterT w m a

dispute :: e -> WriterT w m ()

MonadValidate e m => MonadValidate e (WriterT w m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> WriterT w m a

dispute :: e -> WriterT w m ()

MonadValidate e m => MonadValidate e (StateT s m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> StateT s m a

dispute :: e -> StateT s m ()

MonadValidate e m => MonadValidate e (StateT s m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> StateT s m a

dispute :: e -> StateT s m ()

MonadValidate e m => MonadValidate e (ReaderT r m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> ReaderT r m a

dispute :: e -> ReaderT r m ()

MonadValidate e m => MonadValidate e (IdentityT m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> IdentityT m a

dispute :: e -> IdentityT m ()

MonadValidate e m => MonadValidate e (ExceptT a m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> ExceptT a m a0

dispute :: e -> ExceptT a m ()

(Monad m, Semigroup e) => MonadValidate e (ValidateT e m)

Defined in Control.Monad.Validate.Internal

Methods

refute :: e -> ValidateT e m a

dispute :: e -> ValidateT e m ()

MonadValidate e m => MonadValidate e (ContT r m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> ContT r m a

dispute :: e -> ContT r m ()

(MonadValidate e m, Monoid w) => MonadValidate e (RWST r w s m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> RWST r w s m a

dispute :: e -> RWST r w s m ()

(MonadValidate e m, Monoid w) => MonadValidate e (RWST r w s m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> RWST r w s m a

dispute :: e -> RWST r w s m ()

MonadValidate e m => MonadValidate e (RWST r w s m)

Defined in Control.Monad.Validate.Class

Methods

refute :: e -> RWST r w s m a

dispute :: e -> RWST r w s m ()