Copyright	(c) 2016 Stephen Diehl (c) 2016-2018 Serokell (c) 2018-2023 Kowainik
License	MIT
Maintainer	Kowainik <[email protected]>
Stability	Stable
Portability	Portable
Safe Haskell	Safe
Language	Haskell2010

Relude.Applicative

Contents

Reexports
Combinators

Description

This module contains reexports of Applicative and related functional. Additionally, it provides convenient combinators to work with Applicative.

Synopsis

class Applicative f => Alternative (f :: Type -> Type) where
- empty :: f a
- (<|>) :: f a -> f a -> f a
- some :: f a -> f [a]
- many :: f a -> f [a]
class Functor f => Applicative (f :: Type -> Type) where
- pure :: a -> f a
- (<*>) :: f (a -> b) -> f a -> f b
- liftA2 :: (a -> b -> c) -> f a -> f b -> f c
- (*>) :: f a -> f b -> f b
- (<*) :: f a -> f b -> f a
newtype Const a (b :: k) = Const {
- getConst :: a
}
newtype ZipList a = ZipList {
- getZipList :: [a]
}
liftA3 :: Applicative f => (a -> b -> c -> d) -> f a -> f b -> f c -> f d
optional :: Alternative f => f a -> f (Maybe a)
(<**>) :: Applicative f => f a -> f (a -> b) -> f b
pass :: Applicative f => f ()
appliedTo :: Applicative f => f a -> f (a -> b) -> f b

Reexports

Main data types and functions reexported from Control.Applicative.

class Applicative f => Alternative (f :: Type -> Type) where #

A monoid on applicative functors.

If defined, some and many should be the least solutions of the equations:

```
some v = (:) <$> v <*> many v
```
```
many v = some v <|> pure []
```

Examples

Expand

>>> Nothing <|> Just 42
Just 42

>>> [1, 2] <|> [3, 4]
[1,2,3,4]

>>> empty <|> print (2^15)
32768

Minimal complete definition

empty, (<|>)

Methods

empty :: f a #

The identity of <|>

empty <|> a     == a
a     <|> empty == a

(<|>) :: f a -> f a -> f a infixl 3 #

An associative binary operation

some :: f a -> f [a] #

One or more.

Examples

Expand

>>> some (putStr "la")
lalalalalalalalala... * goes on forever *

>>> some Nothing
nothing

>>> take 5 <$> some (Just 1)
* hangs forever *

Note that this function can be used with Parsers based on Applicatives. In that case some parser will attempt to parse parser one or more times until it fails.

many :: f a -> f [a] #

Zero or more.

Examples

Expand

>>> many (putStr "la")
lalalalalalalalala... * goes on forever *

>>> many Nothing
Just []

>>> take 5 <$> many (Just 1)
* hangs forever *

Note that this function can be used with Parsers based on Applicatives. In that case many parser will attempt to parse parser zero or more times until it fails.

Instances

Instances details

Alternative Seq	Since: containers-0.5.4
Instance details Defined in Data.Sequence.Internal Methods empty :: Seq a # (<\|>) :: Seq a -> Seq a -> Seq a # some :: Seq a -> Seq [a] # many :: Seq a -> Seq [a] #
Alternative STM	Takes the first non-`retry`ing `STM` action. Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Conc.Sync Methods empty :: STM a # (<\|>) :: STM a -> STM a -> STM a # some :: STM a -> STM [a] # many :: STM a -> STM [a] #
Alternative ZipList	Since: base-4.11.0.0
Instance details Defined in GHC.Internal.Functor.ZipList Methods empty :: ZipList a # (<\|>) :: ZipList a -> ZipList a -> ZipList a # some :: ZipList a -> ZipList [a] # many :: ZipList a -> ZipList [a] #
Alternative P	Since: base-4.5.0.0
Instance details Defined in GHC.Internal.Text.ParserCombinators.ReadP Methods empty :: P a # (<\|>) :: P a -> P a -> P a # some :: P a -> P [a] # many :: P a -> P [a] #
Alternative ReadP	Since: base-4.6.0.0
Instance details Defined in GHC.Internal.Text.ParserCombinators.ReadP Methods empty :: ReadP a # (<\|>) :: ReadP a -> ReadP a -> ReadP a # some :: ReadP a -> ReadP [a] # many :: ReadP a -> ReadP [a] #
Alternative ReadPrec	Since: base-4.6.0.0
Instance details Defined in GHC.Internal.Text.ParserCombinators.ReadPrec Methods empty :: ReadPrec a # (<\|>) :: ReadPrec a -> ReadPrec a -> ReadPrec a # some :: ReadPrec a -> ReadPrec [a] # many :: ReadPrec a -> ReadPrec [a] #
Alternative IO	Takes the first non-throwing `IO` action's result. `empty` throws an exception. Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Base Methods empty :: IO a # (<\|>) :: IO a -> IO a -> IO a # some :: IO a -> IO [a] # many :: IO a -> IO [a] #
Alternative Maybe	Picks the leftmost `Just` value, or, alternatively, `Nothing`. Since: base-2.1
Instance details Defined in GHC.Internal.Base Methods empty :: Maybe a # (<\|>) :: Maybe a -> Maybe a -> Maybe a # some :: Maybe a -> Maybe [a] # many :: Maybe a -> Maybe [a] #
Alternative []	Combines lists by concatenation, starting from the empty list. Since: base-2.1
Instance details Defined in GHC.Internal.Base Methods empty :: [a] # (<\|>) :: [a] -> [a] -> [a] # some :: [a] -> [[a]] # many :: [a] -> [[a]] #
MonadPlus m => Alternative (WrappedMonad m)	Since: base-2.1
Instance details Defined in Control.Applicative Methods empty :: WrappedMonad m a # (<\|>) :: WrappedMonad m a -> WrappedMonad m a -> WrappedMonad m a # some :: WrappedMonad m a -> WrappedMonad m [a] # many :: WrappedMonad m a -> WrappedMonad m [a] #
ArrowPlus a => Alternative (ArrowMonad a)	Since: base-4.6.0.0
Instance details Defined in GHC.Internal.Control.Arrow Methods empty :: ArrowMonad a a0 # (<\|>) :: ArrowMonad a a0 -> ArrowMonad a a0 -> ArrowMonad a a0 # some :: ArrowMonad a a0 -> ArrowMonad a [a0] # many :: ArrowMonad a a0 -> ArrowMonad a [a0] #
Alternative (Proxy :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Data.Proxy Methods empty :: Proxy a # (<\|>) :: Proxy a -> Proxy a -> Proxy a # some :: Proxy a -> Proxy [a] # many :: Proxy a -> Proxy [a] #
Alternative (U1 :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods empty :: U1 a # (<\|>) :: U1 a -> U1 a -> U1 a # some :: U1 a -> U1 [a] # many :: U1 a -> U1 [a] #
Alternative f => Alternative (Lift f)	A combination is `Pure` only either part is.
Instance details Defined in Control.Applicative.Lift Methods empty :: Lift f a # (<\|>) :: Lift f a -> Lift f a -> Lift f a # some :: Lift f a -> Lift f [a] # many :: Lift f a -> Lift f [a] #
(Functor m, Monad m) => Alternative (MaybeT m)
Instance details Defined in Control.Monad.Trans.Maybe Methods empty :: MaybeT m a # (<\|>) :: MaybeT m a -> MaybeT m a -> MaybeT m a # some :: MaybeT m a -> MaybeT m [a] # many :: MaybeT m a -> MaybeT m [a] #
(ArrowZero a, ArrowPlus a) => Alternative (WrappedArrow a b)	Since: base-2.1
Instance details Defined in Control.Applicative Methods empty :: WrappedArrow a b a0 # (<\|>) :: WrappedArrow a b a0 -> WrappedArrow a b a0 -> WrappedArrow a b a0 # some :: WrappedArrow a b a0 -> WrappedArrow a b [a0] # many :: WrappedArrow a b a0 -> WrappedArrow a b [a0] #
Alternative m => Alternative (Kleisli m a)	Since: base-4.14.0.0
Instance details Defined in GHC.Internal.Control.Arrow Methods empty :: Kleisli m a a0 # (<\|>) :: Kleisli m a a0 -> Kleisli m a a0 -> Kleisli m a a0 # some :: Kleisli m a a0 -> Kleisli m a [a0] # many :: Kleisli m a a0 -> Kleisli m a [a0] #
Alternative f => Alternative (Ap f)	Since: base-4.12.0.0
Instance details Defined in GHC.Internal.Data.Monoid Methods empty :: Ap f a # (<\|>) :: Ap f a -> Ap f a -> Ap f a # some :: Ap f a -> Ap f [a] # many :: Ap f a -> Ap f [a] #
Alternative f => Alternative (Alt f)	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Data.Semigroup.Internal Methods empty :: Alt f a # (<\|>) :: Alt f a -> Alt f a -> Alt f a # some :: Alt f a -> Alt f [a] # many :: Alt f a -> Alt f [a] #
(Generic1 f, Alternative (Rep1 f)) => Alternative (Generically1 f)	Since: base-4.17.0.0
Instance details Defined in GHC.Internal.Generics Methods empty :: Generically1 f a # (<\|>) :: Generically1 f a -> Generically1 f a -> Generically1 f a # some :: Generically1 f a -> Generically1 f [a] # many :: Generically1 f a -> Generically1 f [a] #
Alternative f => Alternative (Rec1 f)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods empty :: Rec1 f a # (<\|>) :: Rec1 f a -> Rec1 f a -> Rec1 f a # some :: Rec1 f a -> Rec1 f [a] # many :: Rec1 f a -> Rec1 f [a] #
Alternative f => Alternative (Backwards f)	Try alternatives in the same order as `f`.
Instance details Defined in Control.Applicative.Backwards Methods empty :: Backwards f a # (<\|>) :: Backwards f a -> Backwards f a -> Backwards f a # some :: Backwards f a -> Backwards f [a] # many :: Backwards f a -> Backwards f [a] #
(Monoid w, Functor m, MonadPlus m) => Alternative (AccumT w m)
Instance details Defined in Control.Monad.Trans.Accum Methods empty :: AccumT w m a # (<\|>) :: AccumT w m a -> AccumT w m a -> AccumT w m a # some :: AccumT w m a -> AccumT w m [a] # many :: AccumT w m a -> AccumT w m [a] #
(Functor m, Monad m, Monoid e) => Alternative (ExceptT e m)
Instance details Defined in Control.Monad.Trans.Except Methods empty :: ExceptT e m a # (<\|>) :: ExceptT e m a -> ExceptT e m a -> ExceptT e m a # some :: ExceptT e m a -> ExceptT e m [a] # many :: ExceptT e m a -> ExceptT e m [a] #
Alternative m => Alternative (IdentityT m)
Instance details Defined in Control.Monad.Trans.Identity Methods empty :: IdentityT m a # (<\|>) :: IdentityT m a -> IdentityT m a -> IdentityT m a # some :: IdentityT m a -> IdentityT m [a] # many :: IdentityT m a -> IdentityT m [a] #
Alternative m => Alternative (ReaderT r m)
Instance details Defined in Control.Monad.Trans.Reader Methods empty :: ReaderT r m a # (<\|>) :: ReaderT r m a -> ReaderT r m a -> ReaderT r m a # some :: ReaderT r m a -> ReaderT r m [a] # many :: ReaderT r m a -> ReaderT r m [a] #
(Functor m, MonadPlus m) => Alternative (SelectT r m)
Instance details Defined in Control.Monad.Trans.Select Methods empty :: SelectT r m a # (<\|>) :: SelectT r m a -> SelectT r m a -> SelectT r m a # some :: SelectT r m a -> SelectT r m [a] # many :: SelectT r m a -> SelectT r m [a] #
(Functor m, MonadPlus m) => Alternative (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods empty :: StateT s m a # (<\|>) :: StateT s m a -> StateT s m a -> StateT s m a # some :: StateT s m a -> StateT s m [a] # many :: StateT s m a -> StateT s m [a] #
(Functor m, MonadPlus m) => Alternative (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Strict Methods empty :: StateT s m a # (<\|>) :: StateT s m a -> StateT s m a -> StateT s m a # some :: StateT s m a -> StateT s m [a] # many :: StateT s m a -> StateT s m [a] #
(Functor m, MonadPlus m) => Alternative (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.CPS Methods empty :: WriterT w m a # (<\|>) :: WriterT w m a -> WriterT w m a -> WriterT w m a # some :: WriterT w m a -> WriterT w m [a] # many :: WriterT w m a -> WriterT w m [a] #
(Monoid w, Alternative m) => Alternative (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.Lazy Methods empty :: WriterT w m a # (<\|>) :: WriterT w m a -> WriterT w m a -> WriterT w m a # some :: WriterT w m a -> WriterT w m [a] # many :: WriterT w m a -> WriterT w m [a] #
(Monoid w, Alternative m) => Alternative (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.Strict Methods empty :: WriterT w m a # (<\|>) :: WriterT w m a -> WriterT w m a -> WriterT w m a # some :: WriterT w m a -> WriterT w m [a] # many :: WriterT w m a -> WriterT w m [a] #
Alternative f => Alternative (Reverse f)	Derived instance.
Instance details Defined in Data.Functor.Reverse Methods empty :: Reverse f a # (<\|>) :: Reverse f a -> Reverse f a -> Reverse f a # some :: Reverse f a -> Reverse f [a] # many :: Reverse f a -> Reverse f [a] #
(Alternative f, Alternative g) => Alternative (Product f g)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Product Methods empty :: Product f g a # (<\|>) :: Product f g a -> Product f g a -> Product f g a # some :: Product f g a -> Product f g [a] # many :: Product f g a -> Product f g [a] #
(Alternative f, Alternative g) => Alternative (f :*: g)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods empty :: (f :: g) a # (<\|>) :: (f :: g) a -> (f :: g) a -> (f :: g) a # some :: (f :: g) a -> (f :: g) [a] # many :: (f :: g) a -> (f :: g) [a] #
(Alternative f, Applicative g) => Alternative (Compose f g)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Compose Methods empty :: Compose f g a # (<\|>) :: Compose f g a -> Compose f g a -> Compose f g a # some :: Compose f g a -> Compose f g [a] # many :: Compose f g a -> Compose f g [a] #
(Alternative f, Applicative g) => Alternative (f :.: g)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods empty :: (f :.: g) a # (<\|>) :: (f :.: g) a -> (f :.: g) a -> (f :.: g) a # some :: (f :.: g) a -> (f :.: g) [a] # many :: (f :.: g) a -> (f :.: g) [a] #
Alternative f => Alternative (M1 i c f)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods empty :: M1 i c f a # (<\|>) :: M1 i c f a -> M1 i c f a -> M1 i c f a # some :: M1 i c f a -> M1 i c f [a] # many :: M1 i c f a -> M1 i c f [a] #
(Functor m, MonadPlus m) => Alternative (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.CPS Methods empty :: RWST r w s m a # (<\|>) :: RWST r w s m a -> RWST r w s m a -> RWST r w s m a # some :: RWST r w s m a -> RWST r w s m [a] # many :: RWST r w s m a -> RWST r w s m [a] #
(Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.Lazy Methods empty :: RWST r w s m a # (<\|>) :: RWST r w s m a -> RWST r w s m a -> RWST r w s m a # some :: RWST r w s m a -> RWST r w s m [a] # many :: RWST r w s m a -> RWST r w s m [a] #
(Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.Strict Methods empty :: RWST r w s m a # (<\|>) :: RWST r w s m a -> RWST r w s m a -> RWST r w s m a # some :: RWST r w s m a -> RWST r w s m [a] # many :: RWST r w s m a -> RWST r w s m [a] #

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

A functor with application, providing operations to

embed pure expressions (pure), and
sequence computations and combine their results (<*> and liftA2).

A minimal complete definition must include implementations of pure and of either <*> or liftA2. If it defines both, then they must behave the same as their default definitions:

(<*>) = liftA2 id

liftA2 f x y = f <$> x <*> y

Further, any definition must satisfy the following:

Identity

pure id <*> v = v

Composition

pure (.) <*> u <*> v <*> w = u <*> (v <*> w)

Homomorphism

pure f <*> pure x = pure (f x)

Interchange

u <*> pure y = pure ($ y) <*> u

The other methods have the following default definitions, which may be overridden with equivalent specialized implementations:

```
u *> v = (id <$ u) <*> v
```
```
u <* v = liftA2 const u v
```

As a consequence of these laws, the Functor instance for f will satisfy

```
fmap f x = pure f <*> x
```

It may be useful to note that supposing

forall x y. p (q x y) = f x . g y

it follows from the above that

liftA2 p (liftA2 q u v) = liftA2 f u . liftA2 g v

If f is also a Monad, it should satisfy

```
pure = return
```

m1 <*> m2 = m1 >>= (\x1 -> m2 >>= (\x2 -> return (x1 x2)))

```
(*>) = (>>)
```

(which implies that pure and <*> satisfy the applicative functor laws).

Minimal complete definition

pure, ((<*>) | liftA2)

Methods

pure :: a -> f a #

Lift a value into the Structure.

Examples

Expand

>>> pure 1 :: Maybe Int
Just 1

>>> pure 'z' :: [Char]
"z"

>>> pure (pure ":D") :: Maybe [String]
Just [":D"]

(<*>) :: f (a -> b) -> f a -> f b infixl 4 #

Sequential application.

A few functors support an implementation of <*> that is more efficient than the default one.

Example

Expand

Used in combination with (<$>), (<*>) can be used to build a record.

>>> data MyState = MyState {arg1 :: Foo, arg2 :: Bar, arg3 :: Baz}

>>> produceFoo :: Applicative f => f Foo
>>> produceBar :: Applicative f => f Bar
>>> produceBaz :: Applicative f => f Baz

>>> mkState :: Applicative f => f MyState
>>> mkState = MyState <$> produceFoo <*> produceBar <*> produceBaz

liftA2 :: (a -> b -> c) -> f a -> f b -> f c #

Lift a binary function to actions.

Some functors support an implementation of liftA2 that is more efficient than the default one. In particular, if fmap is an expensive operation, it is likely better to use liftA2 than to fmap over the structure and then use <*>.

This became a typeclass method in 4.10.0.0. Prior to that, it was a function defined in terms of <*> and fmap.

Example

Expand

>>> liftA2 (,) (Just 3) (Just 5)
Just (3,5)

>>> liftA2 (+) [1, 2, 3] [4, 5, 6]
[5,6,7,6,7,8,7,8,9]

(*>) :: f a -> f b -> f b infixl 4 #

Sequence actions, discarding the value of the first argument.

Examples

Expand

If used in conjunction with the Applicative instance for Maybe, you can chain Maybe computations, with a possible "early return" in case of Nothing.

>>> Just 2 *> Just 3
Just 3

>>> Nothing *> Just 3
Nothing

Of course a more interesting use case would be to have effectful computations instead of just returning pure values.

>>> import Data.Char
>>> import GHC.Internal.Text.ParserCombinators.ReadP
>>> let p = string "my name is " *> munch1 isAlpha <* eof
>>> readP_to_S p "my name is Simon"
[("Simon","")]

(<*) :: f a -> f b -> f a infixl 4 #

Sequence actions, discarding the value of the second argument.

Instances

Instances details

Applicative Complex	Since: base-4.9.0.0
Instance details Defined in Data.Complex Methods pure :: a -> Complex a # (<>) :: Complex (a -> b) -> Complex a -> Complex b # liftA2 :: (a -> b -> c) -> Complex a -> Complex b -> Complex c # (>) :: Complex a -> Complex b -> Complex b # (<*) :: Complex a -> Complex b -> Complex a #
Applicative First	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods pure :: a -> First a # (<>) :: First (a -> b) -> First a -> First b # liftA2 :: (a -> b -> c) -> First a -> First b -> First c # (>) :: First a -> First b -> First b # (<*) :: First a -> First b -> First a #
Applicative Last	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods pure :: a -> Last a # (<>) :: Last (a -> b) -> Last a -> Last b # liftA2 :: (a -> b -> c) -> Last a -> Last b -> Last c # (>) :: Last a -> Last b -> Last b # (<*) :: Last a -> Last b -> Last a #
Applicative Max	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods pure :: a -> Max a # (<>) :: Max (a -> b) -> Max a -> Max b # liftA2 :: (a -> b -> c) -> Max a -> Max b -> Max c # (>) :: Max a -> Max b -> Max b # (<*) :: Max a -> Max b -> Max a #
Applicative Min	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods pure :: a -> Min a # (<>) :: Min (a -> b) -> Min a -> Min b # liftA2 :: (a -> b -> c) -> Min a -> Min b -> Min c # (>) :: Min a -> Min b -> Min b # (<*) :: Min a -> Min b -> Min a #
Applicative Put
Instance details Defined in Data.ByteString.Builder.Internal Methods pure :: a -> Put a # (<>) :: Put (a -> b) -> Put a -> Put b # liftA2 :: (a -> b -> c) -> Put a -> Put b -> Put c # (>) :: Put a -> Put b -> Put b # (<*) :: Put a -> Put b -> Put a #
Applicative Seq	Since: containers-0.5.4
Instance details Defined in Data.Sequence.Internal Methods pure :: a -> Seq a # (<>) :: Seq (a -> b) -> Seq a -> Seq b # liftA2 :: (a -> b -> c) -> Seq a -> Seq b -> Seq c # (>) :: Seq a -> Seq b -> Seq b # (<*) :: Seq a -> Seq b -> Seq a #
Applicative Tree
Instance details Defined in Data.Tree Methods pure :: a -> Tree a # (<>) :: Tree (a -> b) -> Tree a -> Tree b # liftA2 :: (a -> b -> c) -> Tree a -> Tree b -> Tree c # (>) :: Tree a -> Tree b -> Tree b # (<*) :: Tree a -> Tree b -> Tree a #
Applicative NonEmpty	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Base Methods pure :: a -> NonEmpty a # (<>) :: NonEmpty (a -> b) -> NonEmpty a -> NonEmpty b # liftA2 :: (a -> b -> c) -> NonEmpty a -> NonEmpty b -> NonEmpty c # (>) :: NonEmpty a -> NonEmpty b -> NonEmpty b # (<*) :: NonEmpty a -> NonEmpty b -> NonEmpty a #
Applicative STM	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Conc.Sync Methods pure :: a -> STM a # (<>) :: STM (a -> b) -> STM a -> STM b # liftA2 :: (a -> b -> c) -> STM a -> STM b -> STM c # (>) :: STM a -> STM b -> STM b # (<*) :: STM a -> STM b -> STM a #
Applicative Identity	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Data.Functor.Identity Methods pure :: a -> Identity a # (<>) :: Identity (a -> b) -> Identity a -> Identity b # liftA2 :: (a -> b -> c) -> Identity a -> Identity b -> Identity c # (>) :: Identity a -> Identity b -> Identity b # (<*) :: Identity a -> Identity b -> Identity a #
Applicative First	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Data.Monoid Methods pure :: a -> First a # (<>) :: First (a -> b) -> First a -> First b # liftA2 :: (a -> b -> c) -> First a -> First b -> First c # (>) :: First a -> First b -> First b # (<*) :: First a -> First b -> First a #
Applicative Last	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Data.Monoid Methods pure :: a -> Last a # (<>) :: Last (a -> b) -> Last a -> Last b # liftA2 :: (a -> b -> c) -> Last a -> Last b -> Last c # (>) :: Last a -> Last b -> Last b # (<*) :: Last a -> Last b -> Last a #
Applicative Down	Since: base-4.11.0.0
Instance details Defined in GHC.Internal.Data.Ord Methods pure :: a -> Down a # (<>) :: Down (a -> b) -> Down a -> Down b # liftA2 :: (a -> b -> c) -> Down a -> Down b -> Down c # (>) :: Down a -> Down b -> Down b # (<*) :: Down a -> Down b -> Down a #
Applicative Dual	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Data.Semigroup.Internal Methods pure :: a -> Dual a # (<>) :: Dual (a -> b) -> Dual a -> Dual b # liftA2 :: (a -> b -> c) -> Dual a -> Dual b -> Dual c # (>) :: Dual a -> Dual b -> Dual b # (<*) :: Dual a -> Dual b -> Dual a #
Applicative Product	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Data.Semigroup.Internal Methods pure :: a -> Product a # (<>) :: Product (a -> b) -> Product a -> Product b # liftA2 :: (a -> b -> c) -> Product a -> Product b -> Product c # (>) :: Product a -> Product b -> Product b # (<*) :: Product a -> Product b -> Product a #
Applicative Sum	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Data.Semigroup.Internal Methods pure :: a -> Sum a # (<>) :: Sum (a -> b) -> Sum a -> Sum b # liftA2 :: (a -> b -> c) -> Sum a -> Sum b -> Sum c # (>) :: Sum a -> Sum b -> Sum b # (<*) :: Sum a -> Sum b -> Sum a #
Applicative ZipList	f <$> ZipList xs1 <> ... <> ZipList xsN = ZipList (zipWithN f xs1 ... xsN) where `zipWithN` refers to the `zipWith` function of the appropriate arity (`zipWith`, `zipWith3`, `zipWith4`, ...). For example: (\a b c -> stimes c [a, b]) <$> ZipList "abcd" <> ZipList "567" <> ZipList [1..] = ZipList (zipWith3 (\a b c -> stimes c [a, b]) "abcd" "567" [1..]) = ZipList {getZipList = ["a5","b6b6","c7c7c7"]} Since: base-2.1
Instance details Defined in GHC.Internal.Functor.ZipList Methods pure :: a -> ZipList a # (<>) :: ZipList (a -> b) -> ZipList a -> ZipList b # liftA2 :: (a -> b -> c) -> ZipList a -> ZipList b -> ZipList c # (>) :: ZipList a -> ZipList b -> ZipList b # (<*) :: ZipList a -> ZipList b -> ZipList a #
Applicative Par1	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods pure :: a -> Par1 a # (<>) :: Par1 (a -> b) -> Par1 a -> Par1 b # liftA2 :: (a -> b -> c) -> Par1 a -> Par1 b -> Par1 c # (>) :: Par1 a -> Par1 b -> Par1 b # (<*) :: Par1 a -> Par1 b -> Par1 a #
Applicative P	Since: base-4.5.0.0
Instance details Defined in GHC.Internal.Text.ParserCombinators.ReadP Methods pure :: a -> P a # (<>) :: P (a -> b) -> P a -> P b # liftA2 :: (a -> b -> c) -> P a -> P b -> P c # (>) :: P a -> P b -> P b # (<*) :: P a -> P b -> P a #
Applicative ReadP	Since: base-4.6.0.0
Instance details Defined in GHC.Internal.Text.ParserCombinators.ReadP Methods pure :: a -> ReadP a # (<>) :: ReadP (a -> b) -> ReadP a -> ReadP b # liftA2 :: (a -> b -> c) -> ReadP a -> ReadP b -> ReadP c # (>) :: ReadP a -> ReadP b -> ReadP b # (<*) :: ReadP a -> ReadP b -> ReadP a #
Applicative ReadPrec	Since: base-4.6.0.0
Instance details Defined in GHC.Internal.Text.ParserCombinators.ReadPrec Methods pure :: a -> ReadPrec a # (<>) :: ReadPrec (a -> b) -> ReadPrec a -> ReadPrec b # liftA2 :: (a -> b -> c) -> ReadPrec a -> ReadPrec b -> ReadPrec c # (>) :: ReadPrec a -> ReadPrec b -> ReadPrec b # (<*) :: ReadPrec a -> ReadPrec b -> ReadPrec a #
Applicative IO	Since: base-2.1
Instance details Defined in GHC.Internal.Base Methods pure :: a -> IO a # (<>) :: IO (a -> b) -> IO a -> IO b # liftA2 :: (a -> b -> c) -> IO a -> IO b -> IO c # (>) :: IO a -> IO b -> IO b # (<*) :: IO a -> IO b -> IO a #
Applicative Q
Instance details Defined in Language.Haskell.TH.Syntax Methods pure :: a -> Q a # (<>) :: Q (a -> b) -> Q a -> Q b # liftA2 :: (a -> b -> c) -> Q a -> Q b -> Q c # (>) :: Q a -> Q b -> Q b # (<*) :: Q a -> Q b -> Q a #
Applicative Maybe	Since: base-2.1
Instance details Defined in GHC.Internal.Base Methods pure :: a -> Maybe a # (<>) :: Maybe (a -> b) -> Maybe a -> Maybe b # liftA2 :: (a -> b -> c) -> Maybe a -> Maybe b -> Maybe c # (>) :: Maybe a -> Maybe b -> Maybe b # (<*) :: Maybe a -> Maybe b -> Maybe a #
Applicative Solo	Since: base-4.15
Instance details Defined in GHC.Internal.Base Methods pure :: a -> Solo a # (<>) :: Solo (a -> b) -> Solo a -> Solo b # liftA2 :: (a -> b -> c) -> Solo a -> Solo b -> Solo c # (>) :: Solo a -> Solo b -> Solo b # (<*) :: Solo a -> Solo b -> Solo a #
Applicative []	Since: base-2.1
Instance details Defined in GHC.Internal.Base Methods pure :: a -> [a] # (<>) :: [a -> b] -> [a] -> [b] # liftA2 :: (a -> b -> c) -> [a] -> [b] -> [c] # (>) :: [a] -> [b] -> [b] # (<*) :: [a] -> [b] -> [a] #
Monad m => Applicative (WrappedMonad m)	Since: base-2.1
Instance details Defined in Control.Applicative Methods pure :: a -> WrappedMonad m a # (<>) :: WrappedMonad m (a -> b) -> WrappedMonad m a -> WrappedMonad m b # liftA2 :: (a -> b -> c) -> WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m c # (>) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m b # (<*) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m a #
Applicative (SetM s)
Instance details Defined in Data.Graph Methods pure :: a -> SetM s a # (<>) :: SetM s (a -> b) -> SetM s a -> SetM s b # liftA2 :: (a -> b -> c) -> SetM s a -> SetM s b -> SetM s c # (>) :: SetM s a -> SetM s b -> SetM s b # (<*) :: SetM s a -> SetM s b -> SetM s a #
Arrow a => Applicative (ArrowMonad a)	Since: base-4.6.0.0
Instance details Defined in GHC.Internal.Control.Arrow Methods pure :: a0 -> ArrowMonad a a0 # (<>) :: ArrowMonad a (a0 -> b) -> ArrowMonad a a0 -> ArrowMonad a b # liftA2 :: (a0 -> b -> c) -> ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a c # (>) :: ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a b # (<*) :: ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a a0 #
Applicative (Either e)	Since: base-3.0
Instance details Defined in GHC.Internal.Data.Either Methods pure :: a -> Either e a # (<>) :: Either e (a -> b) -> Either e a -> Either e b # liftA2 :: (a -> b -> c) -> Either e a -> Either e b -> Either e c # (>) :: Either e a -> Either e b -> Either e b # (<*) :: Either e a -> Either e b -> Either e a #
Applicative (Proxy :: Type -> Type)	Since: base-4.7.0.0
Instance details Defined in GHC.Internal.Data.Proxy Methods pure :: a -> Proxy a # (<>) :: Proxy (a -> b) -> Proxy a -> Proxy b # liftA2 :: (a -> b -> c) -> Proxy a -> Proxy b -> Proxy c # (>) :: Proxy a -> Proxy b -> Proxy b # (<*) :: Proxy a -> Proxy b -> Proxy a #
Applicative (U1 :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods pure :: a -> U1 a # (<>) :: U1 (a -> b) -> U1 a -> U1 b # liftA2 :: (a -> b -> c) -> U1 a -> U1 b -> U1 c # (>) :: U1 a -> U1 b -> U1 b # (<*) :: U1 a -> U1 b -> U1 a #
Applicative (IParser t)
Instance details Defined in Data.Text.Internal.Read Methods pure :: a -> IParser t a # (<>) :: IParser t (a -> b) -> IParser t a -> IParser t b # liftA2 :: (a -> b -> c) -> IParser t a -> IParser t b -> IParser t c # (>) :: IParser t a -> IParser t b -> IParser t b # (<*) :: IParser t a -> IParser t b -> IParser t a #
Applicative f => Applicative (Lift f)	A combination is `Pure` only if both parts are.
Instance details Defined in Control.Applicative.Lift Methods pure :: a -> Lift f a # (<>) :: Lift f (a -> b) -> Lift f a -> Lift f b # liftA2 :: (a -> b -> c) -> Lift f a -> Lift f b -> Lift f c # (>) :: Lift f a -> Lift f b -> Lift f b # (<*) :: Lift f a -> Lift f b -> Lift f a #
(Functor m, Monad m) => Applicative (MaybeT m)
Instance details Defined in Control.Monad.Trans.Maybe Methods pure :: a -> MaybeT m a # (<>) :: MaybeT m (a -> b) -> MaybeT m a -> MaybeT m b # liftA2 :: (a -> b -> c) -> MaybeT m a -> MaybeT m b -> MaybeT m c # (>) :: MaybeT m a -> MaybeT m b -> MaybeT m b # (<*) :: MaybeT m a -> MaybeT m b -> MaybeT m a #
Monoid a => Applicative ((,) a)	For tuples, the `Monoid` constraint on `a` determines how the first values merge. For example, `String`s concatenate: ("hello ", (+15)) <> ("world!", 2002) ("hello world!",2017) Since: base-2.1*
Instance details Defined in GHC.Internal.Base Methods pure :: a0 -> (a, a0) # (<>) :: (a, a0 -> b) -> (a, a0) -> (a, b) # liftA2 :: (a0 -> b -> c) -> (a, a0) -> (a, b) -> (a, c) # (>) :: (a, a0) -> (a, b) -> (a, b) # (<*) :: (a, a0) -> (a, b) -> (a, a0) #
Arrow a => Applicative (WrappedArrow a b)	Since: base-2.1
Instance details Defined in Control.Applicative Methods pure :: a0 -> WrappedArrow a b a0 # (<>) :: WrappedArrow a b (a0 -> b0) -> WrappedArrow a b a0 -> WrappedArrow a b b0 # liftA2 :: (a0 -> b0 -> c) -> WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b c # (>) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b b0 # (<*) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b a0 #
(Applicative f, Monad f) => Applicative (WhenMissing f x)	Equivalent to `ReaderT k (ReaderT x (MaybeT f))`. Since: containers-0.5.9
Instance details Defined in Data.IntMap.Internal Methods pure :: a -> WhenMissing f x a # (<>) :: WhenMissing f x (a -> b) -> WhenMissing f x a -> WhenMissing f x b # liftA2 :: (a -> b -> c) -> WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x c # (>) :: WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x b # (<*) :: WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x a #
Applicative m => Applicative (Kleisli m a)	Since: base-4.14.0.0
Instance details Defined in GHC.Internal.Control.Arrow Methods pure :: a0 -> Kleisli m a a0 # (<>) :: Kleisli m a (a0 -> b) -> Kleisli m a a0 -> Kleisli m a b # liftA2 :: (a0 -> b -> c) -> Kleisli m a a0 -> Kleisli m a b -> Kleisli m a c # (>) :: Kleisli m a a0 -> Kleisli m a b -> Kleisli m a b # (<*) :: Kleisli m a a0 -> Kleisli m a b -> Kleisli m a a0 #
Monoid m => Applicative (Const m :: Type -> Type)	Since: base-2.0.1
Instance details Defined in GHC.Internal.Data.Functor.Const Methods pure :: a -> Const m a # (<>) :: Const m (a -> b) -> Const m a -> Const m b # liftA2 :: (a -> b -> c) -> Const m a -> Const m b -> Const m c # (>) :: Const m a -> Const m b -> Const m b # (<*) :: Const m a -> Const m b -> Const m a #
Applicative f => Applicative (Ap f)	Since: base-4.12.0.0
Instance details Defined in GHC.Internal.Data.Monoid Methods pure :: a -> Ap f a # (<>) :: Ap f (a -> b) -> Ap f a -> Ap f b # liftA2 :: (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c # (>) :: Ap f a -> Ap f b -> Ap f b # (<*) :: Ap f a -> Ap f b -> Ap f a #
Applicative f => Applicative (Alt f)	Since: base-4.8.0.0
Instance details Defined in GHC.Internal.Data.Semigroup.Internal Methods pure :: a -> Alt f a # (<>) :: Alt f (a -> b) -> Alt f a -> Alt f b # liftA2 :: (a -> b -> c) -> Alt f a -> Alt f b -> Alt f c # (>) :: Alt f a -> Alt f b -> Alt f b # (<*) :: Alt f a -> Alt f b -> Alt f a #
(Generic1 f, Applicative (Rep1 f)) => Applicative (Generically1 f)	Since: base-4.17.0.0
Instance details Defined in GHC.Internal.Generics Methods pure :: a -> Generically1 f a # (<>) :: Generically1 f (a -> b) -> Generically1 f a -> Generically1 f b # liftA2 :: (a -> b -> c) -> Generically1 f a -> Generically1 f b -> Generically1 f c # (>) :: Generically1 f a -> Generically1 f b -> Generically1 f b # (<*) :: Generically1 f a -> Generically1 f b -> Generically1 f a #
Applicative f => Applicative (Rec1 f)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods pure :: a -> Rec1 f a # (<>) :: Rec1 f (a -> b) -> Rec1 f a -> Rec1 f b # liftA2 :: (a -> b -> c) -> Rec1 f a -> Rec1 f b -> Rec1 f c # (>) :: Rec1 f a -> Rec1 f b -> Rec1 f b # (<*) :: Rec1 f a -> Rec1 f b -> Rec1 f a #
Applicative (t m) => Applicative (LiftingAccum t m)	Since: mtl-2.3
Instance details Defined in Control.Monad.Accum Methods pure :: a -> LiftingAccum t m a # (<>) :: LiftingAccum t m (a -> b) -> LiftingAccum t m a -> LiftingAccum t m b # liftA2 :: (a -> b -> c) -> LiftingAccum t m a -> LiftingAccum t m b -> LiftingAccum t m c # (>) :: LiftingAccum t m a -> LiftingAccum t m b -> LiftingAccum t m b # (<*) :: LiftingAccum t m a -> LiftingAccum t m b -> LiftingAccum t m a #
Applicative (t m) => Applicative (LiftingSelect t m)	Since: mtl-2.3
Instance details Defined in Control.Monad.Select Methods pure :: a -> LiftingSelect t m a # (<>) :: LiftingSelect t m (a -> b) -> LiftingSelect t m a -> LiftingSelect t m b # liftA2 :: (a -> b -> c) -> LiftingSelect t m a -> LiftingSelect t m b -> LiftingSelect t m c # (>) :: LiftingSelect t m a -> LiftingSelect t m b -> LiftingSelect t m b # (<*) :: LiftingSelect t m a -> LiftingSelect t m b -> LiftingSelect t m a #
Applicative f => Applicative (Backwards f)	Apply `f`-actions in the reverse order.
Instance details Defined in Control.Applicative.Backwards Methods pure :: a -> Backwards f a # (<>) :: Backwards f (a -> b) -> Backwards f a -> Backwards f b # liftA2 :: (a -> b -> c) -> Backwards f a -> Backwards f b -> Backwards f c # (>) :: Backwards f a -> Backwards f b -> Backwards f b # (<*) :: Backwards f a -> Backwards f b -> Backwards f a #
(Monoid w, Functor m, Monad m) => Applicative (AccumT w m)
Instance details Defined in Control.Monad.Trans.Accum Methods pure :: a -> AccumT w m a # (<>) :: AccumT w m (a -> b) -> AccumT w m a -> AccumT w m b # liftA2 :: (a -> b -> c) -> AccumT w m a -> AccumT w m b -> AccumT w m c # (>) :: AccumT w m a -> AccumT w m b -> AccumT w m b # (<*) :: AccumT w m a -> AccumT w m b -> AccumT w m a #
(Functor m, Monad m) => Applicative (ExceptT e m)
Instance details Defined in Control.Monad.Trans.Except Methods pure :: a -> ExceptT e m a # (<>) :: ExceptT e m (a -> b) -> ExceptT e m a -> ExceptT e m b # liftA2 :: (a -> b -> c) -> ExceptT e m a -> ExceptT e m b -> ExceptT e m c # (>) :: ExceptT e m a -> ExceptT e m b -> ExceptT e m b # (<*) :: ExceptT e m a -> ExceptT e m b -> ExceptT e m a #
Applicative m => Applicative (IdentityT m)
Instance details Defined in Control.Monad.Trans.Identity Methods pure :: a -> IdentityT m a # (<>) :: IdentityT m (a -> b) -> IdentityT m a -> IdentityT m b # liftA2 :: (a -> b -> c) -> IdentityT m a -> IdentityT m b -> IdentityT m c # (>) :: IdentityT m a -> IdentityT m b -> IdentityT m b # (<*) :: IdentityT m a -> IdentityT m b -> IdentityT m a #
Applicative m => Applicative (ReaderT r m)
Instance details Defined in Control.Monad.Trans.Reader Methods pure :: a -> ReaderT r m a # (<>) :: ReaderT r m (a -> b) -> ReaderT r m a -> ReaderT r m b # liftA2 :: (a -> b -> c) -> ReaderT r m a -> ReaderT r m b -> ReaderT r m c # (>) :: ReaderT r m a -> ReaderT r m b -> ReaderT r m b # (<*) :: ReaderT r m a -> ReaderT r m b -> ReaderT r m a #
(Functor m, Monad m) => Applicative (SelectT r m)
Instance details Defined in Control.Monad.Trans.Select Methods pure :: a -> SelectT r m a # (<>) :: SelectT r m (a -> b) -> SelectT r m a -> SelectT r m b # liftA2 :: (a -> b -> c) -> SelectT r m a -> SelectT r m b -> SelectT r m c # (>) :: SelectT r m a -> SelectT r m b -> SelectT r m b # (<*) :: SelectT r m a -> SelectT r m b -> SelectT r m a #
(Functor m, Monad m) => Applicative (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods pure :: a -> StateT s m a # (<>) :: StateT s m (a -> b) -> StateT s m a -> StateT s m b # liftA2 :: (a -> b -> c) -> StateT s m a -> StateT s m b -> StateT s m c # (>) :: StateT s m a -> StateT s m b -> StateT s m b # (<*) :: StateT s m a -> StateT s m b -> StateT s m a #
(Functor m, Monad m) => Applicative (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Strict Methods pure :: a -> StateT s m a # (<>) :: StateT s m (a -> b) -> StateT s m a -> StateT s m b # liftA2 :: (a -> b -> c) -> StateT s m a -> StateT s m b -> StateT s m c # (>) :: StateT s m a -> StateT s m b -> StateT s m b # (<*) :: StateT s m a -> StateT s m b -> StateT s m a #
(Functor m, Monad m) => Applicative (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.CPS Methods pure :: a -> WriterT w m a # (<>) :: WriterT w m (a -> b) -> WriterT w m a -> WriterT w m b # liftA2 :: (a -> b -> c) -> WriterT w m a -> WriterT w m b -> WriterT w m c # (>) :: WriterT w m a -> WriterT w m b -> WriterT w m b # (<*) :: WriterT w m a -> WriterT w m b -> WriterT w m a #
(Monoid w, Applicative m) => Applicative (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.Lazy Methods pure :: a -> WriterT w m a # (<>) :: WriterT w m (a -> b) -> WriterT w m a -> WriterT w m b # liftA2 :: (a -> b -> c) -> WriterT w m a -> WriterT w m b -> WriterT w m c # (>) :: WriterT w m a -> WriterT w m b -> WriterT w m b # (<*) :: WriterT w m a -> WriterT w m b -> WriterT w m a #
(Monoid w, Applicative m) => Applicative (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.Strict Methods pure :: a -> WriterT w m a # (<>) :: WriterT w m (a -> b) -> WriterT w m a -> WriterT w m b # liftA2 :: (a -> b -> c) -> WriterT w m a -> WriterT w m b -> WriterT w m c # (>) :: WriterT w m a -> WriterT w m b -> WriterT w m b # (<*) :: WriterT w m a -> WriterT w m b -> WriterT w m a #
Monoid a => Applicative (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods pure :: a0 -> Constant a a0 # (<>) :: Constant a (a0 -> b) -> Constant a a0 -> Constant a b # liftA2 :: (a0 -> b -> c) -> Constant a a0 -> Constant a b -> Constant a c # (>) :: Constant a a0 -> Constant a b -> Constant a b # (<*) :: Constant a a0 -> Constant a b -> Constant a a0 #
Applicative f => Applicative (Reverse f)	Derived instance.
Instance details Defined in Data.Functor.Reverse Methods pure :: a -> Reverse f a # (<>) :: Reverse f (a -> b) -> Reverse f a -> Reverse f b # liftA2 :: (a -> b -> c) -> Reverse f a -> Reverse f b -> Reverse f c # (>) :: Reverse f a -> Reverse f b -> Reverse f b # (<*) :: Reverse f a -> Reverse f b -> Reverse f a #
(Monoid a, Monoid b) => Applicative ((,,) a b)	Since: base-4.14.0.0
Instance details Defined in GHC.Internal.Base Methods pure :: a0 -> (a, b, a0) # (<>) :: (a, b, a0 -> b0) -> (a, b, a0) -> (a, b, b0) # liftA2 :: (a0 -> b0 -> c) -> (a, b, a0) -> (a, b, b0) -> (a, b, c) # (>) :: (a, b, a0) -> (a, b, b0) -> (a, b, b0) # (<*) :: (a, b, a0) -> (a, b, b0) -> (a, b, a0) #
(Applicative f, Applicative g) => Applicative (Product f g)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Product Methods pure :: a -> Product f g a # (<>) :: Product f g (a -> b) -> Product f g a -> Product f g b # liftA2 :: (a -> b -> c) -> Product f g a -> Product f g b -> Product f g c # (>) :: Product f g a -> Product f g b -> Product f g b # (<*) :: Product f g a -> Product f g b -> Product f g a #
(Monad f, Applicative f) => Applicative (WhenMatched f x y)	Equivalent to `ReaderT Key (ReaderT x (ReaderT y (MaybeT f)))` Since: containers-0.5.9
Instance details Defined in Data.IntMap.Internal Methods pure :: a -> WhenMatched f x y a # (<>) :: WhenMatched f x y (a -> b) -> WhenMatched f x y a -> WhenMatched f x y b # liftA2 :: (a -> b -> c) -> WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y c # (>) :: WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y b # (<*) :: WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y a #
(Applicative f, Monad f) => Applicative (WhenMissing f k x)	Equivalent to `ReaderT k (ReaderT x (MaybeT f))` . Since: containers-0.5.9
Instance details Defined in Data.Map.Internal Methods pure :: a -> WhenMissing f k x a # (<>) :: WhenMissing f k x (a -> b) -> WhenMissing f k x a -> WhenMissing f k x b # liftA2 :: (a -> b -> c) -> WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x c # (>) :: WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x b # (<*) :: WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x a #
(Applicative f, Applicative g) => Applicative (f :*: g)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods pure :: a -> (f :: g) a # (<>) :: (f :: g) (a -> b) -> (f :: g) a -> (f :: g) b # liftA2 :: (a -> b -> c) -> (f :: g) a -> (f :: g) b -> (f :: g) c # (>) :: (f :: g) a -> (f :: g) b -> (f :: g) b # (<) :: (f :: g) a -> (f :: g) b -> (f :: g) a #
Monoid c => Applicative (K1 i c :: Type -> Type)	Since: base-4.12.0.0
Instance details Defined in GHC.Internal.Generics Methods pure :: a -> K1 i c a # (<>) :: K1 i c (a -> b) -> K1 i c a -> K1 i c b # liftA2 :: (a -> b -> c0) -> K1 i c a -> K1 i c b -> K1 i c c0 # (>) :: K1 i c a -> K1 i c b -> K1 i c b # (<*) :: K1 i c a -> K1 i c b -> K1 i c a #
Applicative (ContT r m)
Instance details Defined in Control.Monad.Trans.Cont Methods pure :: a -> ContT r m a # (<>) :: ContT r m (a -> b) -> ContT r m a -> ContT r m b # liftA2 :: (a -> b -> c) -> ContT r m a -> ContT r m b -> ContT r m c # (>) :: ContT r m a -> ContT r m b -> ContT r m b # (<*) :: ContT r m a -> ContT r m b -> ContT r m a #
(Monoid a, Monoid b, Monoid c) => Applicative ((,,,) a b c)	Since: base-4.14.0.0
Instance details Defined in GHC.Internal.Base Methods pure :: a0 -> (a, b, c, a0) # (<>) :: (a, b, c, a0 -> b0) -> (a, b, c, a0) -> (a, b, c, b0) # liftA2 :: (a0 -> b0 -> c0) -> (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, c0) # (>) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, b0) # (<*) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, a0) #
Applicative ((->) r)	Since: base-2.1
Instance details Defined in GHC.Internal.Base Methods pure :: a -> r -> a # (<>) :: (r -> (a -> b)) -> (r -> a) -> r -> b # liftA2 :: (a -> b -> c) -> (r -> a) -> (r -> b) -> r -> c # (>) :: (r -> a) -> (r -> b) -> r -> b # (<*) :: (r -> a) -> (r -> b) -> r -> a #
(Applicative f, Applicative g) => Applicative (Compose f g)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Compose Methods pure :: a -> Compose f g a # (<>) :: Compose f g (a -> b) -> Compose f g a -> Compose f g b # liftA2 :: (a -> b -> c) -> Compose f g a -> Compose f g b -> Compose f g c # (>) :: Compose f g a -> Compose f g b -> Compose f g b # (<*) :: Compose f g a -> Compose f g b -> Compose f g a #
(Monad f, Applicative f) => Applicative (WhenMatched f k x y)	Equivalent to `ReaderT k (ReaderT x (ReaderT y (MaybeT f)))` Since: containers-0.5.9
Instance details Defined in Data.Map.Internal Methods pure :: a -> WhenMatched f k x y a # (<>) :: WhenMatched f k x y (a -> b) -> WhenMatched f k x y a -> WhenMatched f k x y b # liftA2 :: (a -> b -> c) -> WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y c # (>) :: WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y b # (<*) :: WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y a #
(Applicative f, Applicative g) => Applicative (f :.: g)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods pure :: a -> (f :.: g) a # (<>) :: (f :.: g) (a -> b) -> (f :.: g) a -> (f :.: g) b # liftA2 :: (a -> b -> c) -> (f :.: g) a -> (f :.: g) b -> (f :.: g) c # (>) :: (f :.: g) a -> (f :.: g) b -> (f :.: g) b # (<*) :: (f :.: g) a -> (f :.: g) b -> (f :.: g) a #
Applicative f => Applicative (M1 i c f)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Generics Methods pure :: a -> M1 i c f a # (<>) :: M1 i c f (a -> b) -> M1 i c f a -> M1 i c f b # liftA2 :: (a -> b -> c0) -> M1 i c f a -> M1 i c f b -> M1 i c f c0 # (>) :: M1 i c f a -> M1 i c f b -> M1 i c f b # (<*) :: M1 i c f a -> M1 i c f b -> M1 i c f a #
(Functor m, Monad m) => Applicative (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.CPS Methods pure :: a -> RWST r w s m a # (<>) :: RWST r w s m (a -> b) -> RWST r w s m a -> RWST r w s m b # liftA2 :: (a -> b -> c) -> RWST r w s m a -> RWST r w s m b -> RWST r w s m c # (>) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m b # (<*) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m a #
(Monoid w, Functor m, Monad m) => Applicative (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.Lazy Methods pure :: a -> RWST r w s m a # (<>) :: RWST r w s m (a -> b) -> RWST r w s m a -> RWST r w s m b # liftA2 :: (a -> b -> c) -> RWST r w s m a -> RWST r w s m b -> RWST r w s m c # (>) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m b # (<*) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m a #
(Monoid w, Functor m, Monad m) => Applicative (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.Strict Methods pure :: a -> RWST r w s m a # (<>) :: RWST r w s m (a -> b) -> RWST r w s m a -> RWST r w s m b # liftA2 :: (a -> b -> c) -> RWST r w s m a -> RWST r w s m b -> RWST r w s m c # (>) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m b # (<*) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m a #

newtype Const a (b :: k) #

The Const functor.

Examples

Expand

>>> fmap (++ "World") (Const "Hello")
Const "Hello"

Because we ignore the second type parameter to Const, the Applicative instance, which has (<*>) :: Monoid m => Const m (a -> b) -> Const m a -> Const m b essentially turns into Monoid m => m -> m -> m, which is (<>)

>>> Const [1, 2, 3] <*> Const [4, 5, 6]
Const [1,2,3,4,5,6]

Constructors

Const
Fields getConst :: a

Instances

Instances details

Generic1 (Const a :: k -> Type)

Instance details

Defined in GHC.Internal.Data.Functor.Const

Associated Types

type Rep1 (Const a :: k -> Type)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Data.Functor.Const type Rep1 (Const a :: k -> Type) = D1 ('MetaData "Const" "GHC.Internal.Data.Functor.Const" "ghc-internal" 'True) (C1 ('MetaCons "Const" 'PrefixI 'True) (S1 ('MetaSel ('Just "getConst") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

Methods

from1 :: forall (a0 :: k). Const a a0 -> Rep1 (Const a :: k -> Type) a0 #

to1 :: forall (a0 :: k). Rep1 (Const a :: k -> Type) a0 -> Const a a0 #

Bifoldable (Const :: Type -> Type -> Type)

Since: base-4.10.0.0

Instance details

Defined in Data.Bifoldable

Methods

bifold :: Monoid m => Const m m -> m #

bifoldMap :: Monoid m => (a -> m) -> (b -> m) -> Const a b -> m #

bifoldr :: (a -> c -> c) -> (b -> c -> c) -> c -> Const a b -> c #

bifoldl :: (c -> a -> c) -> (c -> b -> c) -> c -> Const a b -> c #

Bifoldable1 (Const :: Type -> Type -> Type)

Instance details

Defined in Data.Bifoldable1

Methods

bifold1 :: Semigroup m => Const m m -> m #

bifoldMap1 :: Semigroup m => (a -> m) -> (b -> m) -> Const a b -> m #

Bifunctor (Const :: Type -> Type -> Type)

Since: base-4.8.0.0

Instance details

Defined in Data.Bifunctor

Methods

bimap :: (a -> b) -> (c -> d) -> Const a c -> Const b d #

first :: (a -> b) -> Const a c -> Const b c #

second :: (b -> c) -> Const a b -> Const a c #

Bitraversable (Const :: Type -> Type -> Type)

Since: base-4.10.0.0

Instance details

Defined in Data.Bitraversable

Methods

bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Const a b -> f (Const c d) #

Eq2 (Const :: Type -> Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftEq2 :: (a -> b -> Bool) -> (c -> d -> Bool) -> Const a c -> Const b d -> Bool #

Ord2 (Const :: Type -> Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftCompare2 :: (a -> b -> Ordering) -> (c -> d -> Ordering) -> Const a c -> Const b d -> Ordering #

Read2 (Const :: Type -> Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (Const a b) #

liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [Const a b] #

liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (Const a b) #

liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [Const a b] #

Show2 (Const :: Type -> Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftShowsPrec2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> Int -> Const a b -> ShowS #

liftShowList2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> [Const a b] -> ShowS #

NFData2 (Const :: Type -> Type -> Type)

Since: deepseq-1.4.3.0

Instance details

Defined in Control.DeepSeq

Methods

liftRnf2 :: (a -> ()) -> (b -> ()) -> Const a b -> () #

Hashable2 (Const :: Type -> Type -> Type)

Instance details

Defined in Data.Hashable.Class

Methods

liftHashWithSalt2 :: (Int -> a -> Int) -> (Int -> b -> Int) -> Int -> Const a b -> Int Source #

Eq a => Eq1 (Const a :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftEq :: (a0 -> b -> Bool) -> Const a a0 -> Const a b -> Bool #

Ord a => Ord1 (Const a :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftCompare :: (a0 -> b -> Ordering) -> Const a a0 -> Const a b -> Ordering #

Read a => Read1 (Const a :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a0) -> ReadS [a0] -> Int -> ReadS (Const a a0) #

liftReadList :: (Int -> ReadS a0) -> ReadS [a0] -> ReadS [Const a a0] #

liftReadPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec (Const a a0) #

liftReadListPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec [Const a a0] #

Show a => Show1 (Const a :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftShowsPrec :: (Int -> a0 -> ShowS) -> ([a0] -> ShowS) -> Int -> Const a a0 -> ShowS #

liftShowList :: (Int -> a0 -> ShowS) -> ([a0] -> ShowS) -> [Const a a0] -> ShowS #

Contravariant (Const a :: Type -> Type)

Instance details

Defined in Data.Functor.Contravariant

Methods

contramap :: (a' -> a0) -> Const a a0 -> Const a a' #

(>$) :: b -> Const a b -> Const a a0 #

NFData a => NFData1 (Const a :: Type -> Type)

Since: deepseq-1.4.3.0

Instance details

Defined in Control.DeepSeq

Methods

liftRnf :: (a0 -> ()) -> Const a a0 -> () #

Monoid m => Applicative (Const m :: Type -> Type)

Since: base-2.0.1

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

pure :: a -> Const m a #

(<*>) :: Const m (a -> b) -> Const m a -> Const m b #

liftA2 :: (a -> b -> c) -> Const m a -> Const m b -> Const m c #

(*>) :: Const m a -> Const m b -> Const m b #

(<*) :: Const m a -> Const m b -> Const m a #

Functor (Const m :: Type -> Type)

Since: base-2.1

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

fmap :: (a -> b) -> Const m a -> Const m b #

(<$) :: a -> Const m b -> Const m a #

Foldable (Const m :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

fold :: Monoid m0 => Const m m0 -> m0 #

foldMap :: Monoid m0 => (a -> m0) -> Const m a -> m0 #

foldMap' :: Monoid m0 => (a -> m0) -> Const m a -> m0 #

foldr :: (a -> b -> b) -> b -> Const m a -> b #

foldr' :: (a -> b -> b) -> b -> Const m a -> b #

foldl :: (b -> a -> b) -> b -> Const m a -> b #

foldl' :: (b -> a -> b) -> b -> Const m a -> b #

foldr1 :: (a -> a -> a) -> Const m a -> a #

foldl1 :: (a -> a -> a) -> Const m a -> a #

toList :: Const m a -> [a] #

null :: Const m a -> Bool #

length :: Const m a -> Int #

elem :: Eq a => a -> Const m a -> Bool #

maximum :: Ord a => Const m a -> a #

minimum :: Ord a => Const m a -> a #

sum :: Num a => Const m a -> a #

product :: Num a => Const m a -> a #

Traversable (Const m :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in GHC.Internal.Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Const m a -> f (Const m b) #

sequenceA :: Applicative f => Const m (f a) -> f (Const m a) #

mapM :: Monad m0 => (a -> m0 b) -> Const m a -> m0 (Const m b) #

sequence :: Monad m0 => Const m (m0 a) -> m0 (Const m a) #

Hashable a => Hashable1 (Const a :: Type -> Type)

Instance details

Defined in Data.Hashable.Class

Methods

liftHashWithSalt :: (Int -> a0 -> Int) -> Int -> Const a a0 -> Int Source #

NFData a => NFData (Const a b)

Since: deepseq-1.4.0.0

Instance details

Defined in Control.DeepSeq

Methods

rnf :: Const a b -> () #

Monoid a => Monoid (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

mempty :: Const a b #

mappend :: Const a b -> Const a b -> Const a b #

mconcat :: [Const a b] -> Const a b #

Semigroup a => Semigroup (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

(<>) :: Const a b -> Const a b -> Const a b #

sconcat :: NonEmpty (Const a b) -> Const a b #

stimes :: Integral b0 => b0 -> Const a b -> Const a b #

Bits a => Bits (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

(.&.) :: Const a b -> Const a b -> Const a b #

(.|.) :: Const a b -> Const a b -> Const a b #

xor :: Const a b -> Const a b -> Const a b #

complement :: Const a b -> Const a b #

shift :: Const a b -> Int -> Const a b #

rotate :: Const a b -> Int -> Const a b #

zeroBits :: Const a b #

bit :: Int -> Const a b #

setBit :: Const a b -> Int -> Const a b #

clearBit :: Const a b -> Int -> Const a b #

complementBit :: Const a b -> Int -> Const a b #

testBit :: Const a b -> Int -> Bool #

bitSizeMaybe :: Const a b -> Maybe Int #

bitSize :: Const a b -> Int #

isSigned :: Const a b -> Bool #

shiftL :: Const a b -> Int -> Const a b #

unsafeShiftL :: Const a b -> Int -> Const a b #

shiftR :: Const a b -> Int -> Const a b #

unsafeShiftR :: Const a b -> Int -> Const a b #

rotateL :: Const a b -> Int -> Const a b #

rotateR :: Const a b -> Int -> Const a b #

popCount :: Const a b -> Int #

FiniteBits a => FiniteBits (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

finiteBitSize :: Const a b -> Int #

countLeadingZeros :: Const a b -> Int #

countTrailingZeros :: Const a b -> Int #

(Typeable k, Data a, Typeable b) => Data (Const a b)

Since: base-4.10.0.0

Instance details

Defined in GHC.Internal.Data.Data

Methods

gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> Const a b -> c (Const a b) #

gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Const a b) #

toConstr :: Const a b -> Constr #

dataTypeOf :: Const a b -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Const a b)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Const a b)) #

gmapT :: (forall b0. Data b0 => b0 -> b0) -> Const a b -> Const a b #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Const a b -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Const a b -> r #

gmapQ :: (forall d. Data d => d -> u) -> Const a b -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Const a b -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Const a b -> m (Const a b) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Const a b -> m (Const a b) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Const a b -> m (Const a b) #

IsString a => IsString (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.String

Methods

fromString :: String -> Const a b #

Bounded a => Bounded (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

minBound :: Const a b #

maxBound :: Const a b #

Enum a => Enum (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

succ :: Const a b -> Const a b #

pred :: Const a b -> Const a b #

toEnum :: Int -> Const a b #

fromEnum :: Const a b -> Int #

enumFrom :: Const a b -> [Const a b] #

enumFromThen :: Const a b -> Const a b -> [Const a b] #

enumFromTo :: Const a b -> Const a b -> [Const a b] #

enumFromThenTo :: Const a b -> Const a b -> Const a b -> [Const a b] #

Floating a => Floating (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

pi :: Const a b #

exp :: Const a b -> Const a b #

log :: Const a b -> Const a b #

sqrt :: Const a b -> Const a b #

(**) :: Const a b -> Const a b -> Const a b #

logBase :: Const a b -> Const a b -> Const a b #

sin :: Const a b -> Const a b #

cos :: Const a b -> Const a b #

tan :: Const a b -> Const a b #

asin :: Const a b -> Const a b #

acos :: Const a b -> Const a b #

atan :: Const a b -> Const a b #

sinh :: Const a b -> Const a b #

cosh :: Const a b -> Const a b #

tanh :: Const a b -> Const a b #

asinh :: Const a b -> Const a b #

acosh :: Const a b -> Const a b #

atanh :: Const a b -> Const a b #

log1p :: Const a b -> Const a b #

expm1 :: Const a b -> Const a b #

log1pexp :: Const a b -> Const a b #

log1mexp :: Const a b -> Const a b #

RealFloat a => RealFloat (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

floatRadix :: Const a b -> Integer #

floatDigits :: Const a b -> Int #

floatRange :: Const a b -> (Int, Int) #

decodeFloat :: Const a b -> (Integer, Int) #

encodeFloat :: Integer -> Int -> Const a b #

exponent :: Const a b -> Int #

significand :: Const a b -> Const a b #

scaleFloat :: Int -> Const a b -> Const a b #

isNaN :: Const a b -> Bool #

isInfinite :: Const a b -> Bool #

isDenormalized :: Const a b -> Bool #

isNegativeZero :: Const a b -> Bool #

isIEEE :: Const a b -> Bool #

atan2 :: Const a b -> Const a b -> Const a b #

Storable a => Storable (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

sizeOf :: Const a b -> Int #

alignment :: Const a b -> Int #

peekElemOff :: Ptr (Const a b) -> Int -> IO (Const a b) #

pokeElemOff :: Ptr (Const a b) -> Int -> Const a b -> IO () #

peekByteOff :: Ptr b0 -> Int -> IO (Const a b) #

pokeByteOff :: Ptr b0 -> Int -> Const a b -> IO () #

peek :: Ptr (Const a b) -> IO (Const a b) #

poke :: Ptr (Const a b) -> Const a b -> IO () #

Generic (Const a b)

Instance details

Defined in GHC.Internal.Data.Functor.Const

Associated Types

type Rep (Const a b)	Since: base-4.9.0.0
Instance details Defined in GHC.Internal.Data.Functor.Const type Rep (Const a b) = D1 ('MetaData "Const" "GHC.Internal.Data.Functor.Const" "ghc-internal" 'True) (C1 ('MetaCons "Const" 'PrefixI 'True) (S1 ('MetaSel ('Just "getConst") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

Methods

from :: Const a b -> Rep (Const a b) x #

to :: Rep (Const a b) x -> Const a b #

Ix a => Ix (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

range :: (Const a b, Const a b) -> [Const a b] #

index :: (Const a b, Const a b) -> Const a b -> Int #

unsafeIndex :: (Const a b, Const a b) -> Const a b -> Int #

inRange :: (Const a b, Const a b) -> Const a b -> Bool #

rangeSize :: (Const a b, Const a b) -> Int #

unsafeRangeSize :: (Const a b, Const a b) -> Int #

Num a => Num (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

(+) :: Const a b -> Const a b -> Const a b #

(-) :: Const a b -> Const a b -> Const a b #

(*) :: Const a b -> Const a b -> Const a b #

negate :: Const a b -> Const a b #

abs :: Const a b -> Const a b #

signum :: Const a b -> Const a b #

fromInteger :: Integer -> Const a b #

Read a => Read (Const a b)

This instance would be equivalent to the derived instances of the Const newtype if the getConst field were removed

Since: base-4.8.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

readsPrec :: Int -> ReadS (Const a b) #

readList :: ReadS [Const a b] #

readPrec :: ReadPrec (Const a b) #

readListPrec :: ReadPrec [Const a b] #

Fractional a => Fractional (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

(/) :: Const a b -> Const a b -> Const a b #

recip :: Const a b -> Const a b #

fromRational :: Rational -> Const a b #

Integral a => Integral (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

quot :: Const a b -> Const a b -> Const a b #

rem :: Const a b -> Const a b -> Const a b #

div :: Const a b -> Const a b -> Const a b #

mod :: Const a b -> Const a b -> Const a b #

quotRem :: Const a b -> Const a b -> (Const a b, Const a b) #

divMod :: Const a b -> Const a b -> (Const a b, Const a b) #

toInteger :: Const a b -> Integer #

Real a => Real (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

toRational :: Const a b -> Rational #

RealFrac a => RealFrac (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

properFraction :: Integral b0 => Const a b -> (b0, Const a b) #

truncate :: Integral b0 => Const a b -> b0 #

round :: Integral b0 => Const a b -> b0 #

ceiling :: Integral b0 => Const a b -> b0 #

floor :: Integral b0 => Const a b -> b0 #

Show a => Show (Const a b)

This instance would be equivalent to the derived instances of the Const newtype if the getConst field were removed

Since: base-4.8.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

showsPrec :: Int -> Const a b -> ShowS #

show :: Const a b -> String #

showList :: [Const a b] -> ShowS #

Eq a => Eq (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

(==) :: Const a b -> Const a b -> Bool #

(/=) :: Const a b -> Const a b -> Bool #

Ord a => Ord (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

Methods

compare :: Const a b -> Const a b -> Ordering #

(<) :: Const a b -> Const a b -> Bool #

(<=) :: Const a b -> Const a b -> Bool #

(>) :: Const a b -> Const a b -> Bool #

(>=) :: Const a b -> Const a b -> Bool #

max :: Const a b -> Const a b -> Const a b #

min :: Const a b -> Const a b -> Const a b #

Hashable a => Hashable (Const a b)

Instance details

Defined in Data.Hashable.Class

Methods

hashWithSalt :: Int -> Const a b -> Int Source #

hash :: Const a b -> Int Source #

type Rep1 (Const a :: k -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

type Rep1 (Const a :: k -> Type) = D1 ('MetaData "Const" "GHC.Internal.Data.Functor.Const" "ghc-internal" 'True) (C1 ('MetaCons "Const" 'PrefixI 'True) (S1 ('MetaSel ('Just "getConst") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

type Rep (Const a b)

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Functor.Const

type Rep (Const a b) = D1 ('MetaData "Const" "GHC.Internal.Data.Functor.Const" "ghc-internal" 'True) (C1 ('MetaCons "Const" 'PrefixI 'True) (S1 ('MetaSel ('Just "getConst") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

newtype ZipList a #

Lists, but with an Applicative functor based on zipping.

Examples

Expand

In contrast to the Applicative for List:

>>> (+) <$> [1, 2, 3] <*> [4, 5, 6]
[5,6,7,6,7,8,7,8,9]

The Applicative instance of ZipList applies the operation by pairing up the elements, analogous to zipWithN

>>> (+) <$> ZipList [1, 2, 3] <*> ZipList [4, 5, 6]
ZipList {getZipList = [5,7,9]}

>>> (,,,) <$> ZipList [1, 2] <*> ZipList [3, 4] <*> ZipList [5, 6] <*> ZipList [7, 8]
ZipList {getZipList = [(1,3,5,7),(2,4,6,8)]}

>>> ZipList [(+1), (^2), (/ 2)] <*> ZipList [5, 5, 5]
ZipList {getZipList = [6.0,25.0,2.5]}

Constructors

ZipList
Fields getZipList :: [a]

Instances

Instances details

NFData1 ZipList

Since: deepseq-1.4.3.0

Instance details

Defined in Control.DeepSeq

Methods

liftRnf :: (a -> ()) -> ZipList a -> () #

Alternative ZipList

Since: base-4.11.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

empty :: ZipList a #

(<|>) :: ZipList a -> ZipList a -> ZipList a #

some :: ZipList a -> ZipList [a] #

many :: ZipList a -> ZipList [a] #

Applicative ZipList

f <$> ZipList xs1 <*> ... <*> ZipList xsN
    = ZipList (zipWithN f xs1 ... xsN)

where zipWithN refers to the zipWith function of the appropriate arity (zipWith, zipWith3, zipWith4, ...). For example:

(\a b c -> stimes c [a, b]) <$> ZipList "abcd" <*> ZipList "567" <*> ZipList [1..]
    = ZipList (zipWith3 (\a b c -> stimes c [a, b]) "abcd" "567" [1..])
    = ZipList {getZipList = ["a5","b6b6","c7c7c7"]}

Since: base-2.1

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

pure :: a -> ZipList a #

(<*>) :: ZipList (a -> b) -> ZipList a -> ZipList b #

liftA2 :: (a -> b -> c) -> ZipList a -> ZipList b -> ZipList c #

(*>) :: ZipList a -> ZipList b -> ZipList b #

(<*) :: ZipList a -> ZipList b -> ZipList a #

Functor ZipList

Since: base-2.1

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

fmap :: (a -> b) -> ZipList a -> ZipList b #

(<$) :: a -> ZipList b -> ZipList a #

Foldable ZipList

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

fold :: Monoid m => ZipList m -> m #

foldMap :: Monoid m => (a -> m) -> ZipList a -> m #

foldMap' :: Monoid m => (a -> m) -> ZipList a -> m #

foldr :: (a -> b -> b) -> b -> ZipList a -> b #

foldr' :: (a -> b -> b) -> b -> ZipList a -> b #

foldl :: (b -> a -> b) -> b -> ZipList a -> b #

foldl' :: (b -> a -> b) -> b -> ZipList a -> b #

foldr1 :: (a -> a -> a) -> ZipList a -> a #

foldl1 :: (a -> a -> a) -> ZipList a -> a #

toList :: ZipList a -> [a] #

null :: ZipList a -> Bool #

length :: ZipList a -> Int #

elem :: Eq a => a -> ZipList a -> Bool #

maximum :: Ord a => ZipList a -> a #

minimum :: Ord a => ZipList a -> a #

sum :: Num a => ZipList a -> a #

product :: Num a => ZipList a -> a #

Traversable ZipList

Since: base-4.9.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

traverse :: Applicative f => (a -> f b) -> ZipList a -> f (ZipList b) #

sequenceA :: Applicative f => ZipList (f a) -> f (ZipList a) #

mapM :: Monad m => (a -> m b) -> ZipList a -> m (ZipList b) #

sequence :: Monad m => ZipList (m a) -> m (ZipList a) #

Generic1 ZipList

Instance details

Defined in GHC.Internal.Functor.ZipList

Associated Types

type Rep1 ZipList	Since: base-4.7.0.0
Instance details Defined in GHC.Internal.Functor.ZipList type Rep1 ZipList = D1 ('MetaData "ZipList" "GHC.Internal.Functor.ZipList" "ghc-internal" 'True) (C1 ('MetaCons "ZipList" 'PrefixI 'True) (S1 ('MetaSel ('Just "getZipList") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec1 [])))

Methods

from1 :: ZipList a -> Rep1 ZipList a #

to1 :: Rep1 ZipList a -> ZipList a #

NFData a => NFData (ZipList a)

Since: deepseq-1.4.0.0

Instance details

Defined in Control.DeepSeq

Methods

rnf :: ZipList a -> () #

Data a => Data (ZipList a)

Since: base-4.14.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> ZipList a -> c (ZipList a) #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (ZipList a) #

toConstr :: ZipList a -> Constr #

dataTypeOf :: ZipList a -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (ZipList a)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (ZipList a)) #

gmapT :: (forall b. Data b => b -> b) -> ZipList a -> ZipList a #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> ZipList a -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> ZipList a -> r #

gmapQ :: (forall d. Data d => d -> u) -> ZipList a -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> ZipList a -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> ZipList a -> m (ZipList a) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> ZipList a -> m (ZipList a) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> ZipList a -> m (ZipList a) #

Generic (ZipList a)

Instance details

Defined in GHC.Internal.Functor.ZipList

Associated Types

type Rep (ZipList a)	Since: base-4.7.0.0
Instance details Defined in GHC.Internal.Functor.ZipList type Rep (ZipList a) = D1 ('MetaData "ZipList" "GHC.Internal.Functor.ZipList" "ghc-internal" 'True) (C1 ('MetaCons "ZipList" 'PrefixI 'True) (S1 ('MetaSel ('Just "getZipList") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [a])))

Methods

from :: ZipList a -> Rep (ZipList a) x #

to :: Rep (ZipList a) x -> ZipList a #

IsList (ZipList a)

Since: base-4.15.0.0

Instance details

Defined in GHC.Internal.IsList

Associated Types

type Item (ZipList a)
Instance details Defined in GHC.Internal.IsList type Item (ZipList a) = a

Methods

fromList :: [Item (ZipList a)] -> ZipList a #

fromListN :: Int -> [Item (ZipList a)] -> ZipList a #

toList :: ZipList a -> [Item (ZipList a)] #

Read a => Read (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

readsPrec :: Int -> ReadS (ZipList a) #

readList :: ReadS [ZipList a] #

readPrec :: ReadPrec (ZipList a) #

readListPrec :: ReadPrec [ZipList a] #

Show a => Show (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

showsPrec :: Int -> ZipList a -> ShowS #

show :: ZipList a -> String #

showList :: [ZipList a] -> ShowS #

Eq a => Eq (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

(==) :: ZipList a -> ZipList a -> Bool #

(/=) :: ZipList a -> ZipList a -> Bool #

Ord a => Ord (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

Methods

compare :: ZipList a -> ZipList a -> Ordering #

(<) :: ZipList a -> ZipList a -> Bool #

(<=) :: ZipList a -> ZipList a -> Bool #

(>) :: ZipList a -> ZipList a -> Bool #

(>=) :: ZipList a -> ZipList a -> Bool #

max :: ZipList a -> ZipList a -> ZipList a #

min :: ZipList a -> ZipList a -> ZipList a #

type Rep1 ZipList

Since: base-4.7.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

type Rep1 ZipList = D1 ('MetaData "ZipList" "GHC.Internal.Functor.ZipList" "ghc-internal" 'True) (C1 ('MetaCons "ZipList" 'PrefixI 'True) (S1 ('MetaSel ('Just "getZipList") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec1 [])))

type Rep (ZipList a)

Since: base-4.7.0.0

Instance details

Defined in GHC.Internal.Functor.ZipList

type Rep (ZipList a) = D1 ('MetaData "ZipList" "GHC.Internal.Functor.ZipList" "ghc-internal" 'True) (C1 ('MetaCons "ZipList" 'PrefixI 'True) (S1 ('MetaSel ('Just "getZipList") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [a])))

type Item (ZipList a)

Instance details

Defined in GHC.Internal.IsList

type Item (ZipList a) = a

liftA3 :: Applicative f => (a -> b -> c -> d) -> f a -> f b -> f c -> f d #

Lift a ternary function to actions.

optional :: Alternative f => f a -> f (Maybe a) #

One or none.

It is useful for modelling any computation that is allowed to fail.

Examples

Expand

Using the Alternative instance of Control.Monad.Except, the following functions:

>>> import Control.Monad.Except

>>> canFail = throwError "it failed" :: Except String Int
>>> final = return 42                :: Except String Int

Can be combined by allowing the first function to fail:

>>> runExcept $ canFail *> final
Left "it failed"

>>> runExcept $ optional canFail *> final
Right 42

(<**>) :: Applicative f => f a -> f (a -> b) -> f b infixl 4 #

A variant of <*> with the types of the arguments reversed. It differs from flip (<*>) in that the effects are resolved in the order the arguments are presented.

Examples

Expand

>>> (<**>) (print 1) (id <$ print 2)
1
2

>>> flip (<*>) (print 1) (id <$ print 2)
2
1

>>> ZipList [4, 5, 6] <**> ZipList [(+1), (*2), (/3)]
ZipList {getZipList = [5.0,10.0,2.0]}

Combinators

pass :: Applicative f => f () Source #

Shorter alias for pure ().

>>> pass :: Maybe ()
Just ()

Useful shortcut when need an empty action:

printJust :: Maybe Int -> IO ()
printJust mInt = case mInt of
    Just i -> putStrLn $ "Number: " ++ show i
    Nothing -> pass

appliedTo :: Applicative f => f a -> f (a -> b) -> f b Source #

Named version of the <**> operator, which is <*> but flipped. It is helpful for chaining applicative operations in forward applications using &.

>>> Just (+ 1) & appliedTo (Just 2)
Just 3
>>> Just (+) & appliedTo (Just 1) & appliedTo (Just 2)
Just 3
>>> Nothing & appliedTo (Just 2)
Nothing

Since: 0.5.0