Safe Haskell | None |
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- when_ :: Monad m => Bool -> m a -> m ()
- unless_ :: Monad m => Bool -> m a -> m ()
- whenJust :: Monad m => Maybe a -> (a -> m ()) -> m ()
- whenM :: Monad m => m Bool -> m a -> m ()
- unlessM :: Monad m => m Bool -> m a -> m ()
- whenJustM :: Monad m => m (Maybe a) -> (a -> m ()) -> m ()
- ifM :: Monad m => m Bool -> m a -> m a -> m a
- and2M :: Monad m => m Bool -> m Bool -> m Bool
- andM :: Monad m => [m Bool] -> m Bool
- or2M :: Monad m => m Bool -> m Bool -> m Bool
- orM :: Monad m => [m Bool] -> m Bool
- altM1 :: Monad m => (a -> m (Either err b)) -> [a] -> m (Either err b)
- mapM' :: (Foldable t, Monad m, Monoid b) => (a -> m b) -> t a -> m b
- forM' :: (Foldable t, Monad m, Monoid b) => t a -> (a -> m b) -> m b
- type Cont r a = (a -> r) -> r
- thread :: (a -> Cont r b) -> [a] -> Cont r [b]
- zipWithM' :: Monad m => (a -> b -> m c) -> [a] -> [b] -> m [c]
- mapMaybeM :: (Monad m, Functor m) => (a -> m (Maybe b)) -> [a] -> m [b]
- finally :: (Error e, MonadError e m) => m a -> m b -> m a
- bracket :: (Error e, MonadError e m) => m a -> (a -> m c) -> (a -> m b) -> m b
- bracket_ :: Monad m => m a -> (a -> m c) -> m b -> m b
- localState :: MonadState s m => m a -> m a
- readM :: (Error e, MonadError e m, Read a) => String -> m a
- (<$>) :: Functor f => (a -> b) -> f a -> f b
- (<*>) :: Applicative f => forall a b. f (a -> b) -> f a -> f b

# Documentation

when_ :: Monad m => Bool -> m a -> m ()Source

`when_`

is just `Control.Monad.when`

with a more general type.

unless_ :: Monad m => Bool -> m a -> m ()Source

`unless_`

is just `Control.Monad.unless`

with a more general type.

altM1 :: Monad m => (a -> m (Either err b)) -> [a] -> m (Either err b)Source

Lazy monadic disjunction with `Either`

truth values.

mapM' :: (Foldable t, Monad m, Monoid b) => (a -> m b) -> t a -> m bSource

Generalized version of `mapM_ :: Monad m => (a -> m ()) -> [a] -> m ()`

Executes effects and collects results in left-to-right order.
Works best with left-associative monoids.

Note that there is an alternative

mapM' f t = foldr mappend mempty $ mapM f t

that collects results in right-to-left order (effects still right-to-left). It might be preferable for right associative monoids.

forM' :: (Foldable t, Monad m, Monoid b) => t a -> (a -> m b) -> m bSource

Generalized version of `forM_ :: Monad m => [a] -> (a -> m ()) -> m ()`

thread :: (a -> Cont r b) -> [a] -> Cont r [b]Source

`mapM`

for the continuation monad. Terribly useful.

zipWithM' :: Monad m => (a -> b -> m c) -> [a] -> [b] -> m [c]Source

Requires both lists to have the same lengths.

mapMaybeM :: (Monad m, Functor m) => (a -> m (Maybe b)) -> [a] -> m [b]Source

A monadic version of `mapMaybe :: (a -> Maybe b) -> [a] -> [b]`

.

finally :: (Error e, MonadError e m) => m a -> m b -> m aSource

Finally for the `Error`

class. Errors in the finally part take
precedence over prior errors.

:: (Error e, MonadError e m) | |

=> m a | Acquires resource. Run first. |

-> (a -> m c) | Releases resource. Run last. |

-> (a -> m b) | Computes result. Run in-between. |

-> m b |

Bracket for the `Error`

class.

:: Monad m | |

=> m a | Acquires resource. Run first. |

-> (a -> m c) | Releases resource. Run last. |

-> m b | Computes result. Run in-between. |

-> m b |

Bracket without failure. Typically used to preserve state.

localState :: MonadState s m => m a -> m aSource

Restore state after computation.

(<*>) :: Applicative f => forall a b. f (a -> b) -> f a -> f b

Sequential application.