| Safe Haskell | Safe-Inferred |
|---|
MonadUtils
Description
Utilities related to Monad and Applicative classes Mostly for backwards compatability.
- class Functor f => Applicative f where
- (<$>) :: Functor f => (a -> b) -> f a -> f b
- class Monad m => MonadFix m where
- mfix :: (a -> m a) -> m a
- class Monad m => MonadIO m where
- liftIO1 :: MonadIO m => (a -> IO b) -> a -> m b
- liftIO2 :: MonadIO m => (a -> b -> IO c) -> a -> b -> m c
- liftIO3 :: MonadIO m => (a -> b -> c -> IO d) -> a -> b -> c -> m d
- liftIO4 :: MonadIO m => (a -> b -> c -> d -> IO e) -> a -> b -> c -> d -> m e
- zipWith3M :: Monad m => (a -> b -> c -> m d) -> [a] -> [b] -> [c] -> m [d]
- mapAndUnzipM :: Monad m => (a -> m (b, c)) -> [a] -> m ([b], [c])
- mapAndUnzip3M :: Monad m => (a -> m (b, c, d)) -> [a] -> m ([b], [c], [d])
- mapAndUnzip4M :: Monad m => (a -> m (b, c, d, e)) -> [a] -> m ([b], [c], [d], [e])
- mapAccumLM :: Monad m => (acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
- mapSndM :: Monad m => (b -> m c) -> [(a, b)] -> m [(a, c)]
- concatMapM :: Monad m => (a -> m [b]) -> [a] -> m [b]
- mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]
- fmapMaybeM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b)
- fmapEitherM :: Monad m => (a -> m b) -> (c -> m d) -> Either a c -> m (Either b d)
- anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool
- allM :: Monad m => (a -> m Bool) -> [a] -> m Bool
- foldlM :: Monad m => (a -> b -> m a) -> a -> [b] -> m a
- foldlM_ :: Monad m => (a -> b -> m a) -> a -> [b] -> m ()
- foldrM :: Monad m => (b -> a -> m a) -> a -> [b] -> m a
- maybeMapM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b)
Documentation
class Functor f => Applicative f whereSource
A functor with application, providing operations to
A minimal complete definition must include implementations of these functions satisfying the following laws:
- identity
-
pureid<*>v = v - composition
-
pure(.)<*>u<*>v<*>w = u<*>(v<*>w) - homomorphism
-
puref<*>purex =pure(f x) - interchange
-
u<*>purey =pure($y)<*>u
The other methods have the following default definitions, which may be overridden with equivalent specialized implementations:
u *> v = pure (const id) <*> u <*> v
u <* v = pure const <*> u <*> v
As a consequence of these laws, the Functor instance for f will satisfy
fmap f x = pure f <*> x
If f is also a Monad, it should satisfy and
pure = return( (which implies that <*>) = appure and <*> satisfy the
applicative functor laws).
Methods
Lift a value.
(<*>) :: f (a -> b) -> f a -> f bSource
Sequential application.
(*>) :: f a -> f b -> f bSource
Sequence actions, discarding the value of the first argument.
(<*) :: f a -> f b -> f aSource
Sequence actions, discarding the value of the second argument.
Instances
| Applicative [] | |
| Applicative IO | |
| Applicative Q | |
| Applicative Maybe | |
| Applicative Id | |
| Applicative ZipList | |
| Applicative STM | |
| Applicative ReadPrec | |
| Applicative ReadP | |
| Applicative Id | |
| Applicative UniqSM | |
| Applicative Pair | |
| Applicative VM | |
| Applicative CoreM | |
| Applicative ((->) a) | |
| Applicative (Either e) | |
| Monoid a => Applicative ((,) a) | |
| Applicative (ST s) | |
| Applicative (StateL s) | |
| Applicative (StateR s) | |
| Monoid m => Applicative (Const m) | |
| Monad m => Applicative (WrappedMonad m) | |
| Applicative (ST s) | |
| Arrow a => Applicative (ArrowMonad a) | |
| Applicative (State s) | |
| Applicative (State s) | |
| Applicative (IOEnv m) | |
| Arrow a => Applicative (WrappedArrow a b) |
class Monad m => MonadFix m whereSource
Monads having fixed points with a 'knot-tying' semantics.
Instances of MonadFix should satisfy the following laws:
- purity
-
mfix(return. h) =return(fixh) - left shrinking (or tightening)
-
mfix(\x -> a >>= \y -> f x y) = a >>= \y ->mfix(\x -> f x y) - sliding
-
, for strictmfix(liftMh . f) =liftMh (mfix(f . h))h. - nesting
-
mfix(\x ->mfix(\y -> f x y)) =mfix(\x -> f x x)
This class is used in the translation of the recursive do notation
supported by GHC and Hugs.
Methods
liftIO1 :: MonadIO m => (a -> IO b) -> a -> m b
Lift an IO operation with 1 argument into another monad
liftIO2 :: MonadIO m => (a -> b -> IO c) -> a -> b -> m c
Lift an IO operation with 2 arguments into another monad
liftIO3 :: MonadIO m => (a -> b -> c -> IO d) -> a -> b -> c -> m d
Lift an IO operation with 3 arguments into another monad
liftIO4 :: MonadIO m => (a -> b -> c -> d -> IO e) -> a -> b -> c -> d -> m e
Lift an IO operation with 4 arguments into another monad
mapAndUnzipM :: Monad m => (a -> m (b, c)) -> [a] -> m ([b], [c])Source
The mapAndUnzipM function maps its first argument over a list, returning
the result as a pair of lists. This function is mainly used with complicated
data structures or a state-transforming monad.
mapAndUnzip3M :: Monad m => (a -> m (b, c, d)) -> [a] -> m ([b], [c], [d])
mapAndUnzipM for triples
mapAndUnzip4M :: Monad m => (a -> m (b, c, d, e)) -> [a] -> m ([b], [c], [d], [e])
Arguments
| :: Monad m | |
| => (acc -> x -> m (acc, y)) | combining funcction |
| -> acc | initial state |
| -> [x] | inputs |
| -> m (acc, [y]) | final state, outputs |
Monadic version of mapAccumL
concatMapM :: Monad m => (a -> m [b]) -> [a] -> m [b]
Monadic version of concatMap
fmapMaybeM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b)
Monadic version of fmap
fmapEitherM :: Monad m => (a -> m b) -> (c -> m d) -> Either a c -> m (Either b d)
Monadic version of fmap
anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool
Monadic version of any, aborts the computation at the first True value
allM :: Monad m => (a -> m Bool) -> [a] -> m Bool
Monad version of all, aborts the computation at the first False value