Witherable

witherable-0.5: filterable traversable

Copyright | (c) Fumiaki Kinoshita 2020
License | BSD3
Maintainer | Fumiaki Kinoshita <fumiexcel@gmail.com>
Stability | provisional
Portability | non-portable
Safe Haskell | Trustworthy
Language | Haskell2010

Witherable

Contents

- Indexed variants
- Wrapper

Description

Synopsis

- class Functor f => Filterable (f :: Type -> Type) where
  - mapMaybe :: (a -> Maybe b) -> f a -> f b
  - catMaybes :: f (Maybe a) -> f a
  - filter :: (a -> Bool) -> f a -> f a
  - drain :: f a -> f b
- (<$?>) :: Filterable f => (a -> Maybe b) -> f a -> f b
- (<&?>) :: Filterable f => f a -> (a -> Maybe b) -> f b
- class (Traversable t, Filterable t) => Witherable (t :: Type -> Type) where
  - wither :: Applicative f => (a -> f (Maybe b)) -> t a -> f (t b)
  - witherM :: Monad m => (a -> m (Maybe b)) -> t a -> m (t b)
  - filterA :: Applicative f => (a -> f Bool) -> t a -> f (t a)
  - witherMap :: Applicative m => (t b -> r) -> (a -> m (Maybe b)) -> t a -> m r
- ordNub :: (Witherable t, Ord a) => t a -> t a
- ordNubOn :: (Witherable t, Ord b) => (a -> b) -> t a -> t a
- hashNub :: (Witherable t, Eq a, Hashable a) => t a -> t a
- hashNubOn :: (Witherable t, Eq b, Hashable b) => (a -> b) -> t a -> t a
- forMaybe :: (Witherable t, Applicative f) => t a -> (a -> f (Maybe b)) -> f (t b)
- class (FunctorWithIndex i t, Filterable t) => FilterableWithIndex i (t :: Type -> Type) | t -> i where
  - imapMaybe :: (i -> a -> Maybe b) -> t a -> t b
  - ifilter :: (i -> a -> Bool) -> t a -> t a
- class (TraversableWithIndex i t, FilterableWithIndex i t, Witherable t) => WitherableWithIndex i (t :: Type -> Type) | t -> i where
  - iwither :: Applicative f => (i -> a -> f (Maybe b)) -> t a -> f (t b)
  - iwitherM :: Monad m => (i -> a -> m (Maybe b)) -> t a -> m (t b)
  - ifilterA :: Applicative f => (i -> a -> f Bool) -> t a -> f (t a)
- newtype WrappedFoldable (f :: Type -> Type) a = WrapFilterable {
  - unwrapFoldable :: f a
  }

# Documentation

class Functor f => Filterable (f :: Type -> Type) where #

Like `Functor`, but you can remove elements instead of updating them.

Formally, the class `Filterable` represents a functor from `Kleisli Maybe` to `Hask`.

A definition of `mapMaybe` must satisfy the following laws:

conservation
  ``mapMaybe` (Just . f) ≡ `fmap` f`
composition
  ``mapMaybe` f . `mapMaybe` g ≡ `mapMaybe` (f <=< g)`

Minimal complete definition

mapMaybe | catMaybes

Methods

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

Like `mapMaybe`.

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

    catMaybes ≡ mapMaybe id

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

    filter f . filter g ≡ filter (liftA2 (&&) g f)

drain :: f a -> f b #

Empty a filterable.

    drain ≡ mapMaybe (const Nothing)

#### Instances

Instances details

Filterable IntMap # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> IntMap a -> IntMap b # catMaybes :: IntMap (Maybe a) -> IntMap a # filter :: (a -> Bool) -> IntMap a -> IntMap a # drain :: IntMap a -> IntMap b #
Filterable Seq # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Seq a -> Seq b # catMaybes :: Seq (Maybe a) -> Seq a # filter :: (a -> Bool) -> Seq a -> Seq a # drain :: Seq a -> Seq b #
Filterable ZipList # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> ZipList a -> ZipList b # catMaybes :: ZipList (Maybe a) -> ZipList a # filter :: (a -> Bool) -> ZipList a -> ZipList a # drain :: ZipList a -> ZipList b #
Filterable Vector # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Vector a -> Vector b # catMaybes :: Vector (Maybe a) -> Vector a # filter :: (a -> Bool) -> Vector a -> Vector a # drain :: Vector a -> Vector b #
Filterable Maybe # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Maybe a -> Maybe b # catMaybes :: Maybe (Maybe a) -> Maybe a # filter :: (a -> Bool) -> Maybe a -> Maybe a # drain :: Maybe a -> Maybe b #
Filterable [] # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> [a] -> [b] # catMaybes :: [Maybe a] -> [a] # filter :: (a -> Bool) -> [a] -> [a] # drain :: [a] -> [b] #
Filterable (Map k) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Map k a -> Map k b # catMaybes :: Map k (Maybe a) -> Map k a # filter :: (a -> Bool) -> Map k a -> Map k a # drain :: Map k a -> Map k b #
Monoid e => Filterable (Either e) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Either e a -> Either e b # catMaybes :: Either e (Maybe a) -> Either e a # filter :: (a -> Bool) -> Either e a -> Either e a # drain :: Either e a -> Either e b #
Filterable (Proxy :: Type -> Type) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Proxy a -> Proxy b # catMaybes :: Proxy (Maybe a) -> Proxy a # filter :: (a -> Bool) -> Proxy a -> Proxy a # drain :: Proxy a -> Proxy b #
Filterable (U1 :: Type -> Type) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> U1 a -> U1 b # catMaybes :: U1 (Maybe a) -> U1 a # filter :: (a -> Bool) -> U1 a -> U1 a # drain :: U1 a -> U1 b #
Filterable (V1 :: Type -> Type) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> V1 a -> V1 b # catMaybes :: V1 (Maybe a) -> V1 a # filter :: (a -> Bool) -> V1 a -> V1 a # drain :: V1 a -> V1 b #
Functor f => Filterable (MaybeT f) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> MaybeT f a -> MaybeT f b # catMaybes :: MaybeT f (Maybe a) -> MaybeT f a # filter :: (a -> Bool) -> MaybeT f a -> MaybeT f a # drain :: MaybeT f a -> MaybeT f b #
(Eq k, Hashable k) => Filterable (HashMap k) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> HashMap k a -> HashMap k b # catMaybes :: HashMap k (Maybe a) -> HashMap k a # filter :: (a -> Bool) -> HashMap k a -> HashMap k a # drain :: HashMap k a -> HashMap k b #
(Foldable f, Alternative f) => Filterable (WrappedFoldable f) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> WrappedFoldable f a -> WrappedFoldable f b # catMaybes :: WrappedFoldable f (Maybe a) -> WrappedFoldable f a # filter :: (a -> Bool) -> WrappedFoldable f a -> WrappedFoldable f a # drain :: WrappedFoldable f a -> WrappedFoldable f b #
Filterable (Const r :: Type -> Type) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Const r a -> Const r b # catMaybes :: Const r (Maybe a) -> Const r a # filter :: (a -> Bool) -> Const r a -> Const r a # drain :: Const r a -> Const r b #
Filterable f => Filterable (Rec1 f) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Rec1 f a -> Rec1 f b # catMaybes :: Rec1 f (Maybe a) -> Rec1 f a # filter :: (a -> Bool) -> Rec1 f a -> Rec1 f a # drain :: Rec1 f a -> Rec1 f b #
Filterable t => Filterable (Backwards t) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Backwards t a -> Backwards t b # catMaybes :: Backwards t (Maybe a) -> Backwards t a # filter :: (a -> Bool) -> Backwards t a -> Backwards t a # drain :: Backwards t a -> Backwards t b #
Filterable f => Filterable (IdentityT f) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> IdentityT f a -> IdentityT f b # catMaybes :: IdentityT f (Maybe a) -> IdentityT f a # filter :: (a -> Bool) -> IdentityT f a -> IdentityT f a # drain :: IdentityT f a -> IdentityT f b #
Filterable t => Filterable (Reverse t) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Reverse t a -> Reverse t b # catMaybes :: Reverse t (Maybe a) -> Reverse t a # filter :: (a -> Bool) -> Reverse t a -> Reverse t a # drain :: Reverse t a -> Reverse t b #
(Filterable f, Filterable g) => Filterable (Product f g) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Product f g a -> Product f g b # catMaybes :: Product f g (Maybe a) -> Product f g a # filter :: (a -> Bool) -> Product f g a -> Product f g a # drain :: Product f g a -> Product f g b #
(Filterable f, Filterable g) => Filterable (Sum f g) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Sum f g a -> Sum f g b # catMaybes :: Sum f g (Maybe a) -> Sum f g a # filter :: (a -> Bool) -> Sum f g a -> Sum f g a # drain :: Sum f g a -> Sum f g b #
(Filterable f, Filterable g) => Filterable (f :*: g) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> (f :*: g) a -> (f :*: g) b # catMaybes :: (f :*: g) (Maybe a) -> (f :*: g) a # filter :: (a -> Bool) -> (f :*: g) a -> (f :*: g) a # drain :: (f :*: g) a -> (f :*: g) b #
(Filterable f, Filterable g) => Filterable (f :+: g) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> (f :+: g) a -> (f :+: g) b # catMaybes :: (f :+: g) (Maybe a) -> (f :+: g) a # filter :: (a -> Bool) -> (f :+: g) a -> (f :+: g) a # drain :: (f :+: g) a -> (f :+: g) b #
Filterable (K1 i c :: Type -> Type) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> K1 i c a -> K1 i c b # catMaybes :: K1 i c (Maybe a) -> K1 i c a # filter :: (a -> Bool) -> K1 i c a -> K1 i c a # drain :: K1 i c a -> K1 i c b #
(Functor f, Filterable g) => Filterable (Compose f g) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> Compose f g a -> Compose f g b # catMaybes :: Compose f g (Maybe a) -> Compose f g a # filter :: (a -> Bool) -> Compose f g a -> Compose f g a # drain :: Compose f g a -> Compose f g b #
(Functor f, Filterable g) => Filterable (f :.: g) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> (f :.: g) a -> (f :.: g) b # catMaybes :: (f :.: g) (Maybe a) -> (f :.: g) a # filter :: (a -> Bool) -> (f :.: g) a -> (f :.: g) a # drain :: (f :.: g) a -> (f :.: g) b #
Filterable f => Filterable (M1 i c f) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> M1 i c f a -> M1 i c f b # catMaybes :: M1 i c f (Maybe a) -> M1 i c f a # filter :: (a -> Bool) -> M1 i c f a -> M1 i c f a # drain :: M1 i c f a -> M1 i c f b #

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

An infix alias for `mapMaybe`. The name of the operator alludes to `<$>`, and has the same fixity.

Since: 0.3.1

(<&?>) :: Filterable f => f a -> (a -> Maybe b) -> f b infixl 1 #

Flipped version of `<$?>`, the `Filterable` version of `<&>`. It has the same fixity as `<&>`.

    (<&?>) = flip mapMaybe

Since: 0.3.1

class (Traversable t, Filterable t) => Witherable (t :: Type -> Type) where #

An enhancement of `Traversable` with `Filterable`

A definition of `wither` must satisfy the following laws:

identity
  ``wither` (`Identity` . Just) ≡ `Identity``
composition
  ``Compose` . `fmap` (`wither` f) . `wither` g ≡ `wither` (`Compose` . `fmap` (`wither` f) . g)`

Parametricity implies the naturality law:

naturality
  `t . `wither` f ≡ `wither` (t . f)`

  Where `t` is an /applicative transformation/ in the sense described in the `Traversable` documentation.

In the relation to superclasses, these should satisfy too:

conservation
  ``wither` (`fmap` Just . f) = `traverse` f`
pure filter
  ``wither` (`Identity` . f) = `Identity` . `mapMaybe` f`

See the `Properties.md` and `Laws.md` files in the git distribution for more in-depth explanation about properties of `Witherable` containers.

The laws and restrictions are enough to constrain ``wither`` to be uniquely determined as the following default implementation.

    wither f = fmap catMaybes . traverse f

If not to provide better-performing implementation, it's not necessary to implement any one method of `Witherable`. For example, if a type constructor `T` already has instances of `Traversable` and `Filterable`, the next one line is sufficient to provide the `Witherable T` instance.

    instance Witherable T

Minimal complete definition

Nothing

Methods

wither :: Applicative f => (a -> f (Maybe b)) -> t a -> f (t b) #

Effectful `mapMaybe`.

    wither (pure . f) ≡ pure . mapMaybe f

witherM :: Monad m => (a -> m (Maybe b)) -> t a -> m (t b) #

    Monadic variant of wither. This may have more efficient implementation.

filterA :: Applicative f => (a -> f Bool) -> t a -> f (t a) #

witherMap :: Applicative m => (t b -> r) -> (a -> m (Maybe b)) -> t a -> m r #

#### Instances

Instances details

Witherable IntMap # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> IntMap a -> f (IntMap b) # witherM :: Monad m => (a -> m (Maybe b)) -> IntMap a -> m (IntMap b) # filterA :: Applicative f => (a -> f Bool) -> IntMap a -> f (IntMap a) # witherMap :: Applicative m => (IntMap b -> r) -> (a -> m (Maybe b)) -> IntMap a -> m r #
Witherable Seq # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Seq a -> f (Seq b) # witherM :: Monad m => (a -> m (Maybe b)) -> Seq a -> m (Seq b) # filterA :: Applicative f => (a -> f Bool) -> Seq a -> f (Seq a) # witherMap :: Applicative m => (Seq b -> r) -> (a -> m (Maybe b)) -> Seq a -> m r #
Witherable ZipList # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> ZipList a -> f (ZipList b) # witherM :: Monad m => (a -> m (Maybe b)) -> ZipList a -> m (ZipList b) # filterA :: Applicative f => (a -> f Bool) -> ZipList a -> f (ZipList a) # witherMap :: Applicative m => (ZipList b -> r) -> (a -> m (Maybe b)) -> ZipList a -> m r #
Witherable Vector # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Vector a -> f (Vector b) # witherM :: Monad m => (a -> m (Maybe b)) -> Vector a -> m (Vector b) # filterA :: Applicative f => (a -> f Bool) -> Vector a -> f (Vector a) # witherMap :: Applicative m => (Vector b -> r) -> (a -> m (Maybe b)) -> Vector a -> m r #
Witherable Maybe # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Maybe a -> f (Maybe b) # witherM :: Monad m => (a -> m (Maybe b)) -> Maybe a -> m (Maybe b) # filterA :: Applicative f => (a -> f Bool) -> Maybe a -> f (Maybe a) # witherMap :: Applicative m => (Maybe b -> r) -> (a -> m (Maybe b)) -> Maybe a -> m r #
Witherable [] # | Methods are good consumers for fusion.
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> [a] -> f [b] # witherM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b] # filterA :: Applicative f => (a -> f Bool) -> [a] -> f [a] # witherMap :: Applicative m => ([b] -> r) -> (a -> m (Maybe b)) -> [a] -> m r #
Witherable (Map k) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Map k a -> f (Map k b) # witherM :: Monad m => (a -> m (Maybe b)) -> Map k a -> m (Map k b) # filterA :: Applicative f => (a -> f Bool) -> Map k a -> f (Map k a) # witherMap :: Applicative m => (Map k b -> r) -> (a -> m (Maybe b)) -> Map k a -> m r #
Monoid e => Witherable (Either e) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Either e a -> f (Either e b) # witherM :: Monad m => (a -> m (Maybe b)) -> Either e a -> m (Either e b) # filterA :: Applicative f => (a -> f Bool) -> Either e a -> f (Either e a) # witherMap :: Applicative m => (Either e b -> r) -> (a -> m (Maybe b)) -> Either e a -> m r #
Witherable (Proxy :: Type -> Type) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Proxy a -> f (Proxy b) # witherM :: Monad m => (a -> m (Maybe b)) -> Proxy a -> m (Proxy b) # filterA :: Applicative f => (a -> f Bool) -> Proxy a -> f (Proxy a) # witherMap :: Applicative m => (Proxy b -> r) -> (a -> m (Maybe b)) -> Proxy a -> m r #
Witherable (U1 :: Type -> Type) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> U1 a -> f (U1 b) # witherM :: Monad m => (a -> m (Maybe b)) -> U1 a -> m (U1 b) # filterA :: Applicative f => (a -> f Bool) -> U1 a -> f (U1 a) # witherMap :: Applicative m => (U1 b -> r) -> (a -> m (Maybe b)) -> U1 a -> m r #
Witherable (V1 :: Type -> Type) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> V1 a -> f (V1 b) # witherM :: Monad m => (a -> m (Maybe b)) -> V1 a -> m (V1 b) # filterA :: Applicative f => (a -> f Bool) -> V1 a -> f (V1 a) # witherMap :: Applicative m => (V1 b -> r) -> (a -> m (Maybe b)) -> V1 a -> m r #
Traversable t => Witherable (MaybeT t) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> MaybeT t a -> f (MaybeT t b) # witherM :: Monad m => (a -> m (Maybe b)) -> MaybeT t a -> m (MaybeT t b) # filterA :: Applicative f => (a -> f Bool) -> MaybeT t a -> f (MaybeT t a) # witherMap :: Applicative m => (MaybeT t b -> r) -> (a -> m (Maybe b)) -> MaybeT t a -> m r #
(Eq k, Hashable k) => Witherable (HashMap k) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> HashMap k a -> f (HashMap k b) # witherM :: Monad m => (a -> m (Maybe b)) -> HashMap k a -> m (HashMap k b) # filterA :: Applicative f => (a -> f Bool) -> HashMap k a -> f (HashMap k a) # witherMap :: Applicative m => (HashMap k b -> r) -> (a -> m (Maybe b)) -> HashMap k a -> m r #
(Alternative f, Traversable f) => Witherable (WrappedFoldable f) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> WrappedFoldable f a -> f0 (WrappedFoldable f b) # witherM :: Monad m => (a -> m (Maybe b)) -> WrappedFoldable f a -> m (WrappedFoldable f b) # filterA :: Applicative f0 => (a -> f0 Bool) -> WrappedFoldable f a -> f0 (WrappedFoldable f a) # witherMap :: Applicative m => (WrappedFoldable f b -> r) -> (a -> m (Maybe b)) -> WrappedFoldable f a -> m r #
Witherable (Const r :: Type -> Type) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Const r a -> f (Const r b) # witherM :: Monad m => (a -> m (Maybe b)) -> Const r a -> m (Const r b) # filterA :: Applicative f => (a -> f Bool) -> Const r a -> f (Const r a) # witherMap :: Applicative m => (Const r b -> r0) -> (a -> m (Maybe b)) -> Const r a -> m r0 #
Witherable f => Witherable (Rec1 f) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> Rec1 f a -> f0 (Rec1 f b) # witherM :: Monad m => (a -> m (Maybe b)) -> Rec1 f a -> m (Rec1 f b) # filterA :: Applicative f0 => (a -> f0 Bool) -> Rec1 f a -> f0 (Rec1 f a) # witherMap :: Applicative m => (Rec1 f b -> r) -> (a -> m (Maybe b)) -> Rec1 f a -> m r #
Witherable t => Witherable (Backwards t) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Backwards t a -> f (Backwards t b) # witherM :: Monad m => (a -> m (Maybe b)) -> Backwards t a -> m (Backwards t b) # filterA :: Applicative f => (a -> f Bool) -> Backwards t a -> f (Backwards t a) # witherMap :: Applicative m => (Backwards t b -> r) -> (a -> m (Maybe b)) -> Backwards t a -> m r #
Witherable f => Witherable (IdentityT f) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> IdentityT f a -> f0 (IdentityT f b) # witherM :: Monad m => (a -> m (Maybe b)) -> IdentityT f a -> m (IdentityT f b) # filterA :: Applicative f0 => (a -> f0 Bool) -> IdentityT f a -> f0 (IdentityT f a) # witherMap :: Applicative m => (IdentityT f b -> r) -> (a -> m (Maybe b)) -> IdentityT f a -> m r #
Witherable t => Witherable (Reverse t) # | Wither from right to left.
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> Reverse t a -> f (Reverse t b) # witherM :: Monad m => (a -> m (Maybe b)) -> Reverse t a -> m (Reverse t b) # filterA :: Applicative f => (a -> f Bool) -> Reverse t a -> f (Reverse t a) # witherMap :: Applicative m => (Reverse t b -> r) -> (a -> m (Maybe b)) -> Reverse t a -> m r #
(Witherable f, Witherable g) => Witherable (Product f g) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> Product f g a -> f0 (Product f g b) # witherM :: Monad m => (a -> m (Maybe b)) -> Product f g a -> m (Product f g b) # filterA :: Applicative f0 => (a -> f0 Bool) -> Product f g a -> f0 (Product f g a) # witherMap :: Applicative m => (Product f g b -> r) -> (a -> m (Maybe b)) -> Product f g a -> m r #
(Witherable f, Witherable g) => Witherable (Sum f g) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> Sum f g a -> f0 (Sum f g b) # witherM :: Monad m => (a -> m (Maybe b)) -> Sum f g a -> m (Sum f g b) # filterA :: Applicative f0 => (a -> f0 Bool) -> Sum f g a -> f0 (Sum f g a) # witherMap :: Applicative m => (Sum f g b -> r) -> (a -> m (Maybe b)) -> Sum f g a -> m r #
(Witherable f, Witherable g) => Witherable (f :*: g) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> (f :*: g) a -> f0 ((f :*: g) b) # witherM :: Monad m => (a -> m (Maybe b)) -> (f :*: g) a -> m ((f :*: g) b) # filterA :: Applicative f0 => (a -> f0 Bool) -> (f :*: g) a -> f0 ((f :*: g) a) # witherMap :: Applicative m => ((f :*: g) b -> r) -> (a -> m (Maybe b)) -> (f :*: g) a -> m r #
(Witherable f, Witherable g) => Witherable (f :+: g) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> (f :+: g) a -> f0 ((f :+: g) b) # witherM :: Monad m => (a -> m (Maybe b)) -> (f :+: g) a -> m ((f :+: g) b) # filterA :: Applicative f0 => (a -> f0 Bool) -> (f :+: g) a -> f0 ((f :+: g) a) # witherMap :: Applicative m => ((f :+: g) b -> r) -> (a -> m (Maybe b)) -> (f :+: g) a -> m r #
Witherable (K1 i c :: Type -> Type) # |
Instance details Defined in Witherable Methods wither :: Applicative f => (a -> f (Maybe b)) -> K1 i c a -> f (K1 i c b) # witherM :: Monad m => (a -> m (Maybe b)) -> K1 i c a -> m (K1 i c b) # filterA :: Applicative f => (a -> f Bool) -> K1 i c a -> f (K1 i c a) # witherMap :: Applicative m => (K1 i c b -> r) -> (a -> m (Maybe b)) -> K1 i c a -> m r #
(Traversable f, Witherable g) => Witherable (Compose f g) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> Compose f g a -> f0 (Compose f g b) # witherM :: Monad m => (a -> m (Maybe b)) -> Compose f g a -> m (Compose f g b) # filterA :: Applicative f0 => (a -> f0 Bool) -> Compose f g a -> f0 (Compose f g a) # witherMap :: Applicative m => (Compose f g b -> r) -> (a -> m (Maybe b)) -> Compose f g a -> m r #
(Traversable f, Witherable g) => Witherable (f :.: g) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> (f :.: g) a -> f0 ((f :.: g) b) # witherM :: Monad m => (a -> m (Maybe b)) -> (f :.: g) a -> m ((f :.: g) b) # filterA :: Applicative f0 => (a -> f0 Bool) -> (f :.: g) a -> f0 ((f :.: g) a) # witherMap :: Applicative m => ((f :.: g) b -> r) -> (a -> m (Maybe b)) -> (f :.: g) a -> m r #
Witherable f => Witherable (M1 i c f) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> M1 i c f a -> f0 (M1 i c f b) # witherM :: Monad m => (a -> m (Maybe b)) -> M1 i c f a -> m (M1 i c f b) # filterA :: Applicative f0 => (a -> f0 Bool) -> M1 i c f a -> f0 (M1 i c f a) # witherMap :: Applicative m => (M1 i c f b -> r) -> (a -> m (Maybe b)) -> M1 i c f a -> m r #

ordNub :: (Witherable t, Ord a) => t a -> t a #

Removes duplicate elements from a list, keeping only the first occurrence. This is asymptotically faster than using `nub` from Data.List.

    >>> ordNub [3,2,1,3,2,1]
    [3,2,1]

ordNubOn :: (Witherable t, Ord b) => (a -> b) -> t a -> t a #

The `ordNubOn` function behaves just like `ordNub`, except it uses a another type to determine equivalence classes.

    >>> ordNubOn fst [(True, 'x'), (False, 'y'), (True, 'z')]
    [(True,'x'),(False,'y')]

hashNub :: (Witherable t, Eq a, Hashable a) => t a -> t a #

Removes duplicate elements from a list, keeping only the first occurrence. This is usually faster than `ordNub`, especially for things that have a slow comparison (like `String`).

    >>> hashNub [3,2,1,3,2,1]
    [3,2,1]

hashNubOn :: (Witherable t, Eq b, Hashable b) => (a -> b) -> t a -> t a #

The `hashNubOn` function behaves just like `hashNub`, except it uses a another type to determine equivalence classes.

    >>> hashNubOn fst [(True, 'x'), (False, 'y'), (True, 'z')]
    [(True,'x'),(False,'y')]

forMaybe :: (Witherable t, Applicative f) => t a -> (a -> f (Maybe b)) -> f (t b) #

    forMaybe = flip wither

# Indexed variants

class (FunctorWithIndex i t, Filterable t) => FilterableWithIndex i (t :: Type -> Type) | t -> i where #

Indexed variant of `Filterable`.

Minimal complete definition

Nothing

Methods

imapMaybe :: (i -> a -> Maybe b) -> t a -> t b #

ifilter :: (i -> a -> Bool) -> t a -> t a #

    filter f . ifilter g ≡ ifilter (i x -> f x && g i x)

#### Instances

Instances details

FilterableWithIndex () Maybe # |
Instance details Defined in Witherable Methods imapMaybe :: (() -> a -> Maybe b) -> Maybe a -> Maybe b # ifilter :: (() -> a -> Bool) -> Maybe a -> Maybe a #
FilterableWithIndex Int IntMap # |
Instance details Defined in Witherable Methods imapMaybe :: (Int -> a -> Maybe b) -> IntMap a -> IntMap b # ifilter :: (Int -> a -> Bool) -> IntMap a -> IntMap a #
FilterableWithIndex Int Seq # |
Instance details Defined in Witherable Methods imapMaybe :: (Int -> a -> Maybe b) -> Seq a -> Seq b # ifilter :: (Int -> a -> Bool) -> Seq a -> Seq a #
FilterableWithIndex Int ZipList # |
Instance details Defined in Witherable Methods imapMaybe :: (Int -> a -> Maybe b) -> ZipList a -> ZipList b # ifilter :: (Int -> a -> Bool) -> ZipList a -> ZipList a #
FilterableWithIndex Int Vector # |
Instance details Defined in Witherable Methods imapMaybe :: (Int -> a -> Maybe b) -> Vector a -> Vector b # ifilter :: (Int -> a -> Bool) -> Vector a -> Vector a #
FilterableWithIndex Int [] # |
Instance details Defined in Witherable Methods imapMaybe :: (Int -> a -> Maybe b) -> [a] -> [b] # ifilter :: (Int -> a -> Bool) -> [a] -> [a] #
FilterableWithIndex Void (Proxy :: Type -> Type) # |
Instance details Defined in Witherable Methods imapMaybe :: (Void -> a -> Maybe b) -> Proxy a -> Proxy b # ifilter :: (Void -> a -> Bool) -> Proxy a -> Proxy a #
(FunctorWithIndex i f, FoldableWithIndex i f, Alternative f) => FilterableWithIndex i (WrappedFoldable f) # |
Instance details Defined in Witherable Methods imapMaybe :: (i -> a -> Maybe b) -> WrappedFoldable f a -> WrappedFoldable f b # ifilter :: (i -> a -> Bool) -> WrappedFoldable f a -> WrappedFoldable f a #
FilterableWithIndex k (Map k) # |
Instance details Defined in Witherable Methods imapMaybe :: (k -> a -> Maybe b) -> Map k a -> Map k b # ifilter :: (k -> a -> Bool) -> Map k a -> Map k a #
(Eq k, Hashable k) => FilterableWithIndex k (HashMap k) # |
Instance details Defined in Witherable Methods imapMaybe :: (k -> a -> Maybe b) -> HashMap k a -> HashMap k b # ifilter :: (k -> a -> Bool) -> HashMap k a -> HashMap k a #
FilterableWithIndex i t => FilterableWithIndex i (Backwards t) # |
Instance details Defined in Witherable Methods imapMaybe :: (i -> a -> Maybe b) -> Backwards t a -> Backwards t b # ifilter :: (i -> a -> Bool) -> Backwards t a -> Backwards t a #
FilterableWithIndex i f => FilterableWithIndex i (IdentityT f) # |
Instance details Defined in Witherable Methods imapMaybe :: (i -> a -> Maybe b) -> IdentityT f a -> IdentityT f b # ifilter :: (i -> a -> Bool) -> IdentityT f a -> IdentityT f a #
FilterableWithIndex i t => FilterableWithIndex i (Reverse t) # |
Instance details Defined in Witherable Methods imapMaybe :: (i -> a -> Maybe b) -> Reverse t a -> Reverse t b # ifilter :: (i -> a -> Bool) -> Reverse t a -> Reverse t a #
(FilterableWithIndex i f, FilterableWithIndex j g) => FilterableWithIndex (Either i j) (Product f g) # |
Instance details Defined in Witherable Methods imapMaybe :: (Either i j -> a -> Maybe b) -> Product f g a -> Product f g b # ifilter :: (Either i j -> a -> Bool) -> Product f g a -> Product f g a #
(FilterableWithIndex i f, FilterableWithIndex j g) => FilterableWithIndex (Either i j) (Sum f g) # |
Instance details Defined in Witherable Methods imapMaybe :: (Either i j -> a -> Maybe b) -> Sum f g a -> Sum f g b # ifilter :: (Either i j -> a -> Bool) -> Sum f g a -> Sum f g a #
(FunctorWithIndex i f, FilterableWithIndex j g) => FilterableWithIndex (i, j) (Compose f g) # |
Instance details Defined in Witherable Methods imapMaybe :: ((i, j) -> a -> Maybe b) -> Compose f g a -> Compose f g b # ifilter :: ((i, j) -> a -> Bool) -> Compose f g a -> Compose f g a #

class (TraversableWithIndex i t, FilterableWithIndex i t, Witherable t) => WitherableWithIndex i (t :: Type -> Type) | t -> i where #

Indexed variant of `Witherable`.

Minimal complete definition

Nothing

Methods

iwither :: Applicative f => (i -> a -> f (Maybe b)) -> t a -> f (t b) #

Effectful `imapMaybe`.

    iwither ( i -> pure . f i) ≡ pure . imapMaybe f

iwitherM :: Monad m => (i -> a -> m (Maybe b)) -> t a -> m (t b) #

    Monadic variant of wither. This may have more efficient implementation.

ifilterA :: Applicative f => (i -> a -> f Bool) -> t a -> f (t a) #

#### Instances

Instances details

WitherableWithIndex () Maybe # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (() -> a -> f (Maybe b)) -> Maybe a -> f (Maybe b) # iwitherM :: Monad m => (() -> a -> m (Maybe b)) -> Maybe a -> m (Maybe b) # ifilterA :: Applicative f => (() -> a -> f Bool) -> Maybe a -> f (Maybe a) #
WitherableWithIndex Int IntMap # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (Int -> a -> f (Maybe b)) -> IntMap a -> f (IntMap b) # iwitherM :: Monad m => (Int -> a -> m (Maybe b)) -> IntMap a -> m (IntMap b) # ifilterA :: Applicative f => (Int -> a -> f Bool) -> IntMap a -> f (IntMap a) #
WitherableWithIndex Int Seq # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (Int -> a -> f (Maybe b)) -> Seq a -> f (Seq b) # iwitherM :: Monad m => (Int -> a -> m (Maybe b)) -> Seq a -> m (Seq b) # ifilterA :: Applicative f => (Int -> a -> f Bool) -> Seq a -> f (Seq a) #
WitherableWithIndex Int ZipList # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (Int -> a -> f (Maybe b)) -> ZipList a -> f (ZipList b) # iwitherM :: Monad m => (Int -> a -> m (Maybe b)) -> ZipList a -> m (ZipList b) # ifilterA :: Applicative f => (Int -> a -> f Bool) -> ZipList a -> f (ZipList a) #
WitherableWithIndex Int Vector # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (Int -> a -> f (Maybe b)) -> Vector a -> f (Vector b) # iwitherM :: Monad m => (Int -> a -> m (Maybe b)) -> Vector a -> m (Vector b) # ifilterA :: Applicative f => (Int -> a -> f Bool) -> Vector a -> f (Vector a) #
WitherableWithIndex Int [] # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (Int -> a -> f (Maybe b)) -> [a] -> f [b] # iwitherM :: Monad m => (Int -> a -> m (Maybe b)) -> [a] -> m [b] # ifilterA :: Applicative f => (Int -> a -> f Bool) -> [a] -> f [a] #
WitherableWithIndex Void (Proxy :: Type -> Type) # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (Void -> a -> f (Maybe b)) -> Proxy a -> f (Proxy b) # iwitherM :: Monad m => (Void -> a -> m (Maybe b)) -> Proxy a -> m (Proxy b) # ifilterA :: Applicative f => (Void -> a -> f Bool) -> Proxy a -> f (Proxy a) #
WitherableWithIndex k (Map k) # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (k -> a -> f (Maybe b)) -> Map k a -> f (Map k b) # iwitherM :: Monad m => (k -> a -> m (Maybe b)) -> Map k a -> m (Map k b) # ifilterA :: Applicative f => (k -> a -> f Bool) -> Map k a -> f (Map k a) #
(Eq k, Hashable k) => WitherableWithIndex k (HashMap k) # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (k -> a -> f (Maybe b)) -> HashMap k a -> f (HashMap k b) # iwitherM :: Monad m => (k -> a -> m (Maybe b)) -> HashMap k a -> m (HashMap k b) # ifilterA :: Applicative f => (k -> a -> f Bool) -> HashMap k a -> f (HashMap k a) #
WitherableWithIndex i t => WitherableWithIndex i (Backwards t) # |
Instance details Defined in Witherable Methods iwither :: Applicative f => (i -> a -> f (Maybe b)) -> Backwards t a -> f (Backwards t b) # iwitherM :: Monad m => (i -> a -> m (Maybe b)) -> Backwards t a -> m (Backwards t b) # ifilterA :: Applicative f => (i -> a -> f Bool) -> Backwards t a -> f (Backwards t a) #
WitherableWithIndex i f => WitherableWithIndex i (IdentityT f) # |
Instance details Defined in Witherable Methods iwither :: Applicative f0 => (i -> a -> f0 (Maybe b)) -> IdentityT f a -> f0 (IdentityT f b) # iwitherM :: Monad m => (i -> a -> m (Maybe b)) -> IdentityT f a -> m (IdentityT f b) # ifilterA :: Applicative f0 => (i -> a -> f0 Bool) -> IdentityT f a -> f0 (IdentityT f a) #
WitherableWithIndex i t => WitherableWithIndex i (Reverse t) # | Wither from right to left.
Instance details Defined in Witherable Methods iwither :: Applicative f => (i -> a -> f (Maybe b)) -> Reverse t a -> f (Reverse t b) # iwitherM :: Monad m => (i -> a -> m (Maybe b)) -> Reverse t a -> m (Reverse t b) # ifilterA :: Applicative f => (i -> a -> f Bool) -> Reverse t a -> f (Reverse t a) #
(WitherableWithIndex i f, WitherableWithIndex j g) => WitherableWithIndex (Either i j) (Product f g) # |
Instance details Defined in Witherable Methods iwither :: Applicative f0 => (Either i j -> a -> f0 (Maybe b)) -> Product f g a -> f0 (Product f g b) # iwitherM :: Monad m => (Either i j -> a -> m (Maybe b)) -> Product f g a -> m (Product f g b) # ifilterA :: Applicative f0 => (Either i j -> a -> f0 Bool) -> Product f g a -> f0 (Product f g a) #
(WitherableWithIndex i f, WitherableWithIndex j g) => WitherableWithIndex (Either i j) (Sum f g) # |
Instance details Defined in Witherable Methods iwither :: Applicative f0 => (Either i j -> a -> f0 (Maybe b)) -> Sum f g a -> f0 (Sum f g b) # iwitherM :: Monad m => (Either i j -> a -> m (Maybe b)) -> Sum f g a -> m (Sum f g b) # ifilterA :: Applicative f0 => (Either i j -> a -> f0 Bool) -> Sum f g a -> f0 (Sum f g a) #
(TraversableWithIndex i f, WitherableWithIndex j g) => WitherableWithIndex (i, j) (Compose f g) # |
Instance details Defined in Witherable Methods iwither :: Applicative f0 => ((i, j) -> a -> f0 (Maybe b)) -> Compose f g a -> f0 (Compose f g b) # iwitherM :: Monad m => ((i, j) -> a -> m (Maybe b)) -> Compose f g a -> m (Compose f g b) # ifilterA :: Applicative f0 => ((i, j) -> a -> f0 Bool) -> Compose f g a -> f0 (Compose f g a) #

# Wrapper

newtype WrappedFoldable (f :: Type -> Type) a #

Constructors

WrapFilterable |
Fields unwrapFoldable :: f a

#### Instances

Instances details

FoldableWithIndex i f => FoldableWithIndex i (WrappedFoldable f) # |
Instance details Defined in Witherable Methods ifoldMap :: Monoid m => (i -> a -> m) -> WrappedFoldable f a -> m # ifoldMap' :: Monoid m => (i -> a -> m) -> WrappedFoldable f a -> m # ifoldr :: (i -> a -> b -> b) -> b -> WrappedFoldable f a -> b # ifoldl :: (i -> b -> a -> b) -> b -> WrappedFoldable f a -> b # ifoldr' :: (i -> a -> b -> b) -> b -> WrappedFoldable f a -> b # ifoldl' :: (i -> b -> a -> b) -> b -> WrappedFoldable f a -> b #
FunctorWithIndex i f => FunctorWithIndex i (WrappedFoldable f) # |
Instance details Defined in Witherable Methods imap :: (i -> a -> b) -> WrappedFoldable f a -> WrappedFoldable f b #
TraversableWithIndex i f => TraversableWithIndex i (WrappedFoldable f) # |
Instance details Defined in Witherable Methods itraverse :: Applicative f0 => (i -> a -> f0 b) -> WrappedFoldable f a -> f0 (WrappedFoldable f b) #
(FunctorWithIndex i f, FoldableWithIndex i f, Alternative f) => FilterableWithIndex i (WrappedFoldable f) # |
Instance details Defined in Witherable Methods imapMaybe :: (i -> a -> Maybe b) -> WrappedFoldable f a -> WrappedFoldable f b # ifilter :: (i -> a -> Bool) -> WrappedFoldable f a -> WrappedFoldable f a #
Alternative f => Alternative (WrappedFoldable f) # |
Instance details Defined in Witherable Methods empty :: WrappedFoldable f a # (<|>) :: WrappedFoldable f a -> WrappedFoldable f a -> WrappedFoldable f a # some :: WrappedFoldable f a -> WrappedFoldable f [a] # many :: WrappedFoldable f a -> WrappedFoldable f [a] #
Applicative f => Applicative (WrappedFoldable f) # |
Instance details Defined in Witherable Methods pure :: a -> WrappedFoldable f a # (<*>) :: WrappedFoldable f (a -> b) -> WrappedFoldable f a -> WrappedFoldable f b # liftA2 :: (a -> b -> c) -> WrappedFoldable f a -> WrappedFoldable f b -> WrappedFoldable f c # (*>) :: WrappedFoldable f a -> WrappedFoldable f b -> WrappedFoldable f b # (<*) :: WrappedFoldable f a -> WrappedFoldable f b -> WrappedFoldable f a #
Functor f => Functor (WrappedFoldable f) # |
Instance details Defined in Witherable Methods fmap :: (a -> b) -> WrappedFoldable f a -> WrappedFoldable f b # (<$) :: a -> WrappedFoldable f b -> WrappedFoldable f a #
Foldable f => Foldable (WrappedFoldable f) # |
Instance details Defined in Witherable Methods fold :: Monoid m => WrappedFoldable f m -> m # foldMap :: Monoid m => (a -> m) -> WrappedFoldable f a -> m # foldMap' :: Monoid m => (a -> m) -> WrappedFoldable f a -> m # foldr :: (a -> b -> b) -> b -> WrappedFoldable f a -> b # foldr' :: (a -> b -> b) -> b -> WrappedFoldable f a -> b # foldl :: (b -> a -> b) -> b -> WrappedFoldable f a -> b # foldl' :: (b -> a -> b) -> b -> WrappedFoldable f a -> b # foldr1 :: (a -> a -> a) -> WrappedFoldable f a -> a # foldl1 :: (a -> a -> a) -> WrappedFoldable f a -> a # toList :: WrappedFoldable f a -> [a] # null :: WrappedFoldable f a -> Bool # length :: WrappedFoldable f a -> Int # elem :: Eq a => a -> WrappedFoldable f a -> Bool # maximum :: Ord a => WrappedFoldable f a -> a # minimum :: Ord a => WrappedFoldable f a -> a # sum :: Num a => WrappedFoldable f a -> a # product :: Num a => WrappedFoldable f a -> a #
Traversable f => Traversable (WrappedFoldable f) # |
Instance details Defined in Witherable Methods traverse :: Applicative f0 => (a -> f0 b) -> WrappedFoldable f a -> f0 (WrappedFoldable f b) # sequenceA :: Applicative f0 => WrappedFoldable f (f0 a) -> f0 (WrappedFoldable f a) # mapM :: Monad m => (a -> m b) -> WrappedFoldable f a -> m (WrappedFoldable f b) # sequence :: Monad m => WrappedFoldable f (m a) -> m (WrappedFoldable f a) #
(Foldable f, Alternative f) => Filterable (WrappedFoldable f) # |
Instance details Defined in Witherable Methods mapMaybe :: (a -> Maybe b) -> WrappedFoldable f a -> WrappedFoldable f b # catMaybes :: WrappedFoldable f (Maybe a) -> WrappedFoldable f a # filter :: (a -> Bool) -> WrappedFoldable f a -> WrappedFoldable f a # drain :: WrappedFoldable f a -> WrappedFoldable f b #
(Alternative f, Traversable f) => Witherable (WrappedFoldable f) # |
Instance details Defined in Witherable Methods wither :: Applicative f0 => (a -> f0 (Maybe b)) -> WrappedFoldable f a -> f0 (WrappedFoldable f b) # witherM :: Monad m => (a -> m (Maybe b)) -> WrappedFoldable f a -> m (WrappedFoldable f b) # filterA :: Applicative f0 => (a -> f0 Bool) -> WrappedFoldable f a -> f0 (WrappedFoldable f a) # witherMap :: Applicative m => (WrappedFoldable f b -> r) -> (a -> m (Maybe b)) -> WrappedFoldable f a -> m r #