Safe Haskell	Safe-Inferred
Language	Haskell2010

Ganeti.Utils.Monad

Description

Utility functions for MonadPlus operations

Synopsis

mretryN :: MonadPlus m => Int -> (Int -> m a) -> m a
retryMaybeN :: Monad m => Int -> (Int -> MaybeT m a) -> m (Maybe a)
anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool
allM :: Monad m => (a -> m Bool) -> [a] -> m Bool
orM :: Monad m => [m Bool] -> m Bool
unfoldrM :: Monad m => (a -> m (Maybe (b, a))) -> a -> m [b]
unfoldrM' :: (Monad m, MonadPlus f) => (a -> m (Maybe (b, a))) -> a -> m (f b)
retryErrorN :: MonadError e m => Int -> (Int -> m a) -> m a

Documentation

mretryN :: MonadPlus m => Int -> (Int -> m a) -> m a #

Retries the given action up to n times. The action signals failure by mzero.

retryMaybeN :: Monad m => Int -> (Int -> MaybeT m a) -> m (Maybe a) #

Retries the given action up to n times. The action signals failure by mzero.

anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool #

Short-circuit any with a monadic predicate.

allM :: Monad m => (a -> m Bool) -> [a] -> m Bool #

Short-circuit all with a monadic predicate.

orM :: Monad m => [m Bool] -> m Bool #

Short-circuit or for values of type Monad m => m Bool

unfoldrM :: Monad m => (a -> m (Maybe (b, a))) -> a -> m [b] #

See unfoldr. This is a monad-friendly version of that.

unfoldrM' :: (Monad m, MonadPlus f) => (a -> m (Maybe (b, a))) -> a -> m (f b) #

See unfoldr. This is a monad-friendly version of that, with a twist. Rather than returning a list, it returns any MonadPlus type of your choice.

retryErrorN :: MonadError e m => Int -> (Int -> m a) -> m a #

Retries the given action up to n times until it succeeds. If all actions fail, the error of the last one is returned. The action is always run at least once, even if n is less than 1.