Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Filtrable

Synopsis

class Functor f => Filtrable f where
- mapMaybe :: (a -> Maybe b) -> f a -> f b
- catMaybes :: f (Maybe a) -> f a
- filter :: (a -> Bool) -> f a -> f a
- mapMaybeA :: (Traversable f, Applicative p) => (a -> p (Maybe b)) -> f a -> p (f b)
- filterA :: (Traversable f, Applicative p) => (a -> p Bool) -> f a -> p (f a)
- mapEither :: (a -> Either b c) -> f a -> (f b, f c)
- mapEitherA :: (Traversable f, Applicative p) => (a -> p (Either b c)) -> f a -> p (f b, f c)
- partitionEithers :: f (Either a b) -> (f a, f b)
(<$?>) :: Filtrable f => (a -> Maybe b) -> f a -> f b
(<*?>) :: (Applicative p, Filtrable p) => p (a -> Maybe b) -> p a -> p b
nub :: (Filtrable f, Traversable f, Eq a) => f a -> f a
nubBy :: (Filtrable f, Traversable f) => (a -> a -> Bool) -> f a -> f a
nubOrd :: (Filtrable f, Traversable f, Ord a) => f a -> f a
nubOrdBy :: (Filtrable f, Traversable f) => (a -> a -> Ordering) -> f a -> f a

Documentation

class Functor f => Filtrable f where Source #

Class of filtrable containers, i.e. containers we can map over while selectively dropping elements.

Laws:

```
mapMaybe Just = id
```
```
mapMaybe f = catMaybes ∘ fmap f
```
```
catMaybes = mapMaybe id
```

filter f = mapMaybe (\ x -> bool Nothing (Just x) (f x))

mapMaybe g . mapMaybe f = mapMaybe (g <=< f)

Laws if Foldable f:

foldMap g . filter f = foldMap (\ x -> bool mempty (g x) (f x))

Minimal complete definition

mapMaybe | catMaybes

Methods

mapMaybe :: (a -> Maybe b) -> f a -> f b Source #

Map the container with the given function, dropping the elements for which it returns Nothing.

catMaybes :: f (Maybe a) -> f a Source #

catMaybes = mapMaybe id

filter :: (a -> Bool) -> f a -> f a Source #

Drop the elements for which the given predicate is False.

mapMaybeA :: (Traversable f, Applicative p) => (a -> p (Maybe b)) -> f a -> p (f b) Source #

Traverse the container with the given function, dropping the elements for which it returns Nothing.

filterA :: (Traversable f, Applicative p) => (a -> p Bool) -> f a -> p (f a) Source #

Drop the elements for which the given predicate is False.

mapEither :: (a -> Either b c) -> f a -> (f b, f c) Source #

Map the container with the given function, collecting the Lefts and the Rights separately.

mapEitherA :: (Traversable f, Applicative p) => (a -> p (Either b c)) -> f a -> p (f b, f c) Source #

Traverse the container with the given function, collecting the Lefts and the Rights separately.

partitionEithers :: f (Either a b) -> (f a, f b) Source #

partitionEithers = mapEither id

Instances

Instances details

Filtrable [] Source #
Instance details Defined in Data.Filtrable Methods mapMaybe :: (a -> Maybe b) -> [a] -> [b] Source # catMaybes :: [Maybe a] -> [a] Source # filter :: (a -> Bool) -> [a] -> [a] Source # mapMaybeA :: (Traversable [], Applicative p) => (a -> p (Maybe b)) -> [a] -> p [b] Source # filterA :: (Traversable [], Applicative p) => (a -> p Bool) -> [a] -> p [a] Source # mapEither :: (a -> Either b c) -> [a] -> ([b], [c]) Source # mapEitherA :: (Traversable [], Applicative p) => (a -> p (Either b c)) -> [a] -> p ([b], [c]) Source # partitionEithers :: [Either a b] -> ([a], [b]) Source #
Filtrable Maybe Source #
Instance details Defined in Data.Filtrable Methods mapMaybe :: (a -> Maybe b) -> Maybe a -> Maybe b Source # catMaybes :: Maybe (Maybe a) -> Maybe a Source # filter :: (a -> Bool) -> Maybe a -> Maybe a Source # mapMaybeA :: (Traversable Maybe, Applicative p) => (a -> p (Maybe b)) -> Maybe a -> p (Maybe b) Source # filterA :: (Traversable Maybe, Applicative p) => (a -> p Bool) -> Maybe a -> p (Maybe a) Source # mapEither :: (a -> Either b c) -> Maybe a -> (Maybe b, Maybe c) Source # mapEitherA :: (Traversable Maybe, Applicative p) => (a -> p (Either b c)) -> Maybe a -> p (Maybe b, Maybe c) Source # partitionEithers :: Maybe (Either a b) -> (Maybe a, Maybe b) Source #
Filtrable (Proxy :: Type -> Type) Source #
Instance details Defined in Data.Filtrable Methods mapMaybe :: (a -> Maybe b) -> Proxy a -> Proxy b Source # catMaybes :: Proxy (Maybe a) -> Proxy a Source # filter :: (a -> Bool) -> Proxy a -> Proxy a Source # mapMaybeA :: (Traversable Proxy, Applicative p) => (a -> p (Maybe b)) -> Proxy a -> p (Proxy b) Source # filterA :: (Traversable Proxy, Applicative p) => (a -> p Bool) -> Proxy a -> p (Proxy a) Source # mapEither :: (a -> Either b c) -> Proxy a -> (Proxy b, Proxy c) Source # mapEitherA :: (Traversable Proxy, Applicative p) => (a -> p (Either b c)) -> Proxy a -> p (Proxy b, Proxy c) Source # partitionEithers :: Proxy (Either a b) -> (Proxy a, Proxy b) Source #
Filtrable (Const a :: Type -> Type) Source #
Instance details Defined in Data.Filtrable Methods mapMaybe :: (a0 -> Maybe b) -> Const a a0 -> Const a b Source # catMaybes :: Const a (Maybe a0) -> Const a a0 Source # filter :: (a0 -> Bool) -> Const a a0 -> Const a a0 Source # mapMaybeA :: (Traversable (Const a), Applicative p) => (a0 -> p (Maybe b)) -> Const a a0 -> p (Const a b) Source # filterA :: (Traversable (Const a), Applicative p) => (a0 -> p Bool) -> Const a a0 -> p (Const a a0) Source # mapEither :: (a0 -> Either b c) -> Const a a0 -> (Const a b, Const a c) Source # mapEitherA :: (Traversable (Const a), Applicative p) => (a0 -> p (Either b c)) -> Const a a0 -> p (Const a b, Const a c) Source # partitionEithers :: Const a (Either a0 b) -> (Const a a0, Const a b) Source #
(Filtrable f, Filtrable g) => Filtrable (Product f g) Source #
Instance details Defined in Data.Filtrable Methods mapMaybe :: (a -> Maybe b) -> Product f g a -> Product f g b Source # catMaybes :: Product f g (Maybe a) -> Product f g a Source # filter :: (a -> Bool) -> Product f g a -> Product f g a Source # mapMaybeA :: (Traversable (Product f g), Applicative p) => (a -> p (Maybe b)) -> Product f g a -> p (Product f g b) Source # filterA :: (Traversable (Product f g), Applicative p) => (a -> p Bool) -> Product f g a -> p (Product f g a) Source # mapEither :: (a -> Either b c) -> Product f g a -> (Product f g b, Product f g c) Source # mapEitherA :: (Traversable (Product f g), Applicative p) => (a -> p (Either b c)) -> Product f g a -> p (Product f g b, Product f g c) Source # partitionEithers :: Product f g (Either a b) -> (Product f g a, Product f g b) Source #
(Filtrable f, Filtrable g) => Filtrable (Sum f g) Source #
Instance details Defined in Data.Filtrable Methods mapMaybe :: (a -> Maybe b) -> Sum f g a -> Sum f g b Source # catMaybes :: Sum f g (Maybe a) -> Sum f g a Source # filter :: (a -> Bool) -> Sum f g a -> Sum f g a Source # mapMaybeA :: (Traversable (Sum f g), Applicative p) => (a -> p (Maybe b)) -> Sum f g a -> p (Sum f g b) Source # filterA :: (Traversable (Sum f g), Applicative p) => (a -> p Bool) -> Sum f g a -> p (Sum f g a) Source # mapEither :: (a -> Either b c) -> Sum f g a -> (Sum f g b, Sum f g c) Source # mapEitherA :: (Traversable (Sum f g), Applicative p) => (a -> p (Either b c)) -> Sum f g a -> p (Sum f g b, Sum f g c) Source # partitionEithers :: Sum f g (Either a b) -> (Sum f g a, Sum f g b) Source #
(Functor f, Filtrable g) => Filtrable (Compose f g) Source #
Instance details Defined in Data.Filtrable Methods mapMaybe :: (a -> Maybe b) -> Compose f g a -> Compose f g b Source # catMaybes :: Compose f g (Maybe a) -> Compose f g a Source # filter :: (a -> Bool) -> Compose f g a -> Compose f g a Source # mapMaybeA :: (Traversable (Compose f g), Applicative p) => (a -> p (Maybe b)) -> Compose f g a -> p (Compose f g b) Source # filterA :: (Traversable (Compose f g), Applicative p) => (a -> p Bool) -> Compose f g a -> p (Compose f g a) Source # mapEither :: (a -> Either b c) -> Compose f g a -> (Compose f g b, Compose f g c) Source # mapEitherA :: (Traversable (Compose f g), Applicative p) => (a -> p (Either b c)) -> Compose f g a -> p (Compose f g b, Compose f g c) Source # partitionEithers :: Compose f g (Either a b) -> (Compose f g a, Compose f g b) Source #

(<$?>) :: Filtrable f => (a -> Maybe b) -> f a -> f b infixl 4 Source #

(<*?>) :: (Applicative p, Filtrable p) => p (a -> Maybe b) -> p a -> p b infixl 4 Source #

nub :: (Filtrable f, Traversable f, Eq a) => f a -> f a Source #

$\mathcal{O}(n^2)$ Delete all but the first copy of each element, special case of nubBy.

nubBy :: (Filtrable f, Traversable f) => (a -> a -> Bool) -> f a -> f a Source #

$\mathcal{O}(n^2)$ Delete all but the first copy of each element, with the given relation.

nubOrd :: (Filtrable f, Traversable f, Ord a) => f a -> f a Source #

$\mathcal{O}(n^2)$ Delete all but the first copy of each element, special case of nubOrdBy.

nubOrdBy :: (Filtrable f, Traversable f) => (a -> a -> Ordering) -> f a -> f a Source #

$\mathcal{O}(n^2)$ Delete all but the first copy of each element, with the given relation.