Safe Haskell	Safe
Language	Haskell2010

Applicative

Contents

Applicative
Alternative
- Newtypes
Free applicative

Synopsis

class Functor f => Applicative (f :: * -> *) where
between :: Applicative m => m open -> m close -> m a -> m a
filterM :: Applicative m => (a -> m Bool) -> [a] -> m [a]
forever :: Applicative f => f a -> f b
liftA3 :: Applicative f => (a -> b -> c -> d) -> f a -> f b -> f c -> f d
replicateM :: Applicative m => Int -> m a -> m [a]
replicateM_ :: Applicative m => Int -> m a -> m ()
unless :: Applicative f => Bool -> f () -> f ()
when :: Applicative f => Bool -> f () -> f ()
zipWithM :: Applicative m => (a -> b -> m c) -> [a] -> [b] -> m [c]
zipWithM_ :: Applicative m => (a -> b -> m c) -> [a] -> [b] -> m ()
class Applicative f => Alternative (f :: * -> *) where
endBy :: Alternative m => m a -> m sep -> m [a]
endBy1 :: Alternative m => m a -> m sep -> m (NonEmpty a)
guard :: Alternative f => Bool -> f ()
manyTill :: Alternative m => m a -> m end -> m [a]
optional :: (Alt f, Applicative f) => f a -> f (Maybe a)
sepBy :: Alternative m => m a -> m sep -> m [a]
sepEndBy :: Alternative m => m a -> m sep -> m [a]
sepBy1 :: Alternative m => m a -> m sep -> m (NonEmpty a)
sepEndBy1 :: Alternative m => m a -> m sep -> m (NonEmpty a)
skipMany :: Alternative m => m a -> m ()
skipManyTill :: Alternative m => m a -> m end -> m end
skipSome :: Alternative m => m a -> m ()
skipSomeTill :: Alternative m => m a -> m end -> m end
some1 :: Alternative f => f a -> f (NonEmpty a)
someTill :: Alternative m => m a -> m end -> m (NonEmpty a)
newtype Alt (f :: k -> *) (a :: k) :: forall k. (k -> *) -> k -> * = Alt {
- getAlt :: f a
}
data Ap (f :: * -> *) a where
- Pure :: Ap f a
- Ap :: Ap f a
runAp :: Applicative g => (forall x. f x -> g x) -> Ap f a -> g a
runAp_ :: Monoid m => (forall a. f a -> m) -> Ap f b -> m
liftAp :: f a -> Ap f a
iterAp :: Functor g => (g a -> a) -> Ap g a -> a
hoistAp :: (forall a. f a -> g a) -> Ap f b -> Ap g b
retractAp :: Applicative f => Ap f a -> f a

Applicative

class Functor f => Applicative (f :: * -> *) 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
```
```
(<*>) = ap
```
```
(*>) = (>>)
```

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

Minimal complete definition

pure, ((<*>) | liftA2)

Methods

pure :: a -> f a #

Lift a value.

(<*>) :: 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.

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 <*>.

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

Sequence actions, discarding the value of the first argument.

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

Sequence actions, discarding the value of the second argument.

Instances

Applicative []	Since: base-2.1
Instance details Defined in GHC.Base Methods pure :: a -> [a] # (<>) :: [a -> b] -> [a] -> [b] # liftA2 :: (a -> b -> c) -> [a] -> [b] -> [c] # (>) :: [a] -> [b] -> [b] # (<*) :: [a] -> [b] -> [a] #
Applicative Maybe	Since: base-2.1
Instance details Defined in GHC.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 IO	Since: base-2.1
Instance details Defined in GHC.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 Par1	Since: base-4.9.0.0
Instance details Defined in GHC.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 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 IResult
Instance details Defined in Data.Aeson.Types.Internal Methods pure :: a -> IResult a # (<>) :: IResult (a -> b) -> IResult a -> IResult b # liftA2 :: (a -> b -> c) -> IResult a -> IResult b -> IResult c # (>) :: IResult a -> IResult b -> IResult b # (<*) :: IResult a -> IResult b -> IResult a #
Applicative Result
Instance details Defined in Data.Aeson.Types.Internal Methods pure :: a -> Result a # (<>) :: Result (a -> b) -> Result a -> Result b # liftA2 :: (a -> b -> c) -> Result a -> Result b -> Result c # (>) :: Result a -> Result b -> Result b # (<*) :: Result a -> Result b -> Result a #
Applicative Parser
Instance details Defined in Data.Aeson.Types.Internal Methods pure :: a -> Parser a # (<>) :: Parser (a -> b) -> Parser a -> Parser b # liftA2 :: (a -> b -> c) -> Parser a -> Parser b -> Parser c # (>) :: Parser a -> Parser b -> Parser b # (<*) :: Parser a -> Parser b -> Parser a #
Applicative Approximate
Instance details Defined in Data.Approximate.Type Methods pure :: a -> Approximate a # (<>) :: Approximate (a -> b) -> Approximate a -> Approximate b # liftA2 :: (a -> b -> c) -> Approximate a -> Approximate b -> Approximate c # (>) :: Approximate a -> Approximate b -> Approximate b # (<*) :: Approximate a -> Approximate b -> Approximate a #
Applicative Concurrently
Instance details Defined in Control.Concurrent.Async Methods pure :: a -> Concurrently a # (<>) :: Concurrently (a -> b) -> Concurrently a -> Concurrently b # liftA2 :: (a -> b -> c) -> Concurrently a -> Concurrently b -> Concurrently c # (>) :: Concurrently a -> Concurrently b -> Concurrently b # (<*) :: Concurrently a -> Concurrently b -> Concurrently a #
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 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 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 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 Option	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods pure :: a -> Option a # (<>) :: Option (a -> b) -> Option a -> Option b # liftA2 :: (a -> b -> c) -> Option a -> Option b -> Option c # (>) :: Option a -> Option b -> Option b # (<*) :: Option a -> Option b -> Option 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 Control.Applicative 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 Identity	Since: base-4.8.0.0
Instance details Defined in 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 STM	Since: base-4.8.0.0
Instance details Defined in GHC.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 First
Instance details Defined in 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
Instance details Defined in 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 Dual	Since: base-4.8.0.0
Instance details Defined in 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 Sum	Since: base-4.8.0.0
Instance details Defined in 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 Product	Since: base-4.8.0.0
Instance details Defined in 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 Down	Since: base-4.11.0.0
Instance details Defined in 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 ReadPrec	Since: base-4.6.0.0
Instance details Defined in 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 ReadP	Since: base-4.6.0.0
Instance details Defined in 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 NonEmpty	Since: base-4.9.0.0
Instance details Defined in GHC.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 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 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 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 DList
Instance details Defined in Data.DList Methods pure :: a -> DList a # (<>) :: DList (a -> b) -> DList a -> DList b # liftA2 :: (a -> b -> c) -> DList a -> DList b -> DList c # (>) :: DList a -> DList b -> DList b # (<*) :: DList a -> DList b -> DList a #
Applicative Eval
Instance details Defined in Control.Parallel.Strategies Methods pure :: a -> Eval a # (<>) :: Eval (a -> b) -> Eval a -> Eval b # liftA2 :: (a -> b -> c) -> Eval a -> Eval b -> Eval c # (>) :: Eval a -> Eval b -> Eval b # (<*) :: Eval a -> Eval b -> Eval a #
Applicative Vector
Instance details Defined in Data.Vector Methods pure :: a -> Vector a # (<>) :: Vector (a -> b) -> Vector a -> Vector b # liftA2 :: (a -> b -> c) -> Vector a -> Vector b -> Vector c # (>) :: Vector a -> Vector b -> Vector b # (<*) :: Vector a -> Vector b -> Vector a #
Applicative Log
Instance details Defined in Numeric.Log Methods pure :: a -> Log a # (<>) :: Log (a -> b) -> Log a -> Log b # liftA2 :: (a -> b -> c) -> Log a -> Log b -> Log c # (>) :: Log a -> Log b -> Log b # (<*) :: Log a -> Log b -> Log a #
Applicative Managed
Instance details Defined in Control.Monad.Managed Methods pure :: a -> Managed a # (<>) :: Managed (a -> b) -> Managed a -> Managed b # liftA2 :: (a -> b -> c) -> Managed a -> Managed b -> Managed c # (>) :: Managed a -> Managed b -> Managed b # (<*) :: Managed a -> Managed b -> Managed a #
Applicative ReadM
Instance details Defined in Options.Applicative.Types Methods pure :: a -> ReadM a # (<>) :: ReadM (a -> b) -> ReadM a -> ReadM b # liftA2 :: (a -> b -> c) -> ReadM a -> ReadM b -> ReadM c # (>) :: ReadM a -> ReadM b -> ReadM b # (<*) :: ReadM a -> ReadM b -> ReadM a #
Applicative Parser
Instance details Defined in Options.Applicative.Types Methods pure :: a -> Parser a # (<>) :: Parser (a -> b) -> Parser a -> Parser b # liftA2 :: (a -> b -> c) -> Parser a -> Parser b -> Parser c # (>) :: Parser a -> Parser b -> Parser b # (<*) :: Parser a -> Parser b -> Parser a #
Applicative ParserM
Instance details Defined in Options.Applicative.Types Methods pure :: a -> ParserM a # (<>) :: ParserM (a -> b) -> ParserM a -> ParserM b # liftA2 :: (a -> b -> c) -> ParserM a -> ParserM b -> ParserM c # (>) :: ParserM a -> ParserM b -> ParserM b # (<*) :: ParserM a -> ParserM b -> ParserM a #
Applicative ParserResult
Instance details Defined in Options.Applicative.Types Methods pure :: a -> ParserResult a # (<>) :: ParserResult (a -> b) -> ParserResult a -> ParserResult b # liftA2 :: (a -> b -> c) -> ParserResult a -> ParserResult b -> ParserResult c # (>) :: ParserResult a -> ParserResult b -> ParserResult b # (<*) :: ParserResult a -> ParserResult b -> ParserResult a #
Applicative SmallArray
Instance details Defined in Data.Primitive.SmallArray Methods pure :: a -> SmallArray a # (<>) :: SmallArray (a -> b) -> SmallArray a -> SmallArray b # liftA2 :: (a -> b -> c) -> SmallArray a -> SmallArray b -> SmallArray c # (>) :: SmallArray a -> SmallArray b -> SmallArray b # (<*) :: SmallArray a -> SmallArray b -> SmallArray a #
Applicative Array
Instance details Defined in Data.Primitive.Array Methods pure :: a -> Array a # (<>) :: Array (a -> b) -> Array a -> Array b # liftA2 :: (a -> b -> c) -> Array a -> Array b -> Array c # (>) :: Array a -> Array b -> Array b # (<*) :: Array a -> Array b -> Array a #
Applicative Behavior	The function `pure` returns a value that is constant in time. Semantically, pure :: a -> Behavior a pure x = \time -> x The combinator `<>` applies a time-varying function to a time-varying value. (<>) :: Behavior (a -> b) -> Behavior a -> Behavior b fx <*> bx = \time -> fx time $ bx time
Instance details Defined in Reactive.Banana.Types Methods pure :: a -> Behavior a # (<>) :: Behavior (a -> b) -> Behavior a -> Behavior b # liftA2 :: (a -> b -> c) -> Behavior a -> Behavior b -> Behavior c # (>) :: Behavior a -> Behavior b -> Behavior b # (<*) :: Behavior a -> Behavior b -> Behavior a #
Applicative Future
Instance details Defined in Reactive.Banana.Types Methods pure :: a -> Future a # (<>) :: Future (a -> b) -> Future a -> Future b # liftA2 :: (a -> b -> c) -> Future a -> Future b -> Future c # (>) :: Future a -> Future b -> Future b # (<*) :: Future a -> Future b -> Future a #
Applicative Moment
Instance details Defined in Reactive.Banana.Types Methods pure :: a -> Moment a # (<>) :: Moment (a -> b) -> Moment a -> Moment b # liftA2 :: (a -> b -> c) -> Moment a -> Moment b -> Moment c # (>) :: Moment a -> Moment b -> Moment b # (<*) :: Moment a -> Moment b -> Moment a #
Applicative MomentIO
Instance details Defined in Reactive.Banana.Types Methods pure :: a -> MomentIO a # (<>) :: MomentIO (a -> b) -> MomentIO a -> MomentIO b # liftA2 :: (a -> b -> c) -> MomentIO a -> MomentIO b -> MomentIO c # (>) :: MomentIO a -> MomentIO b -> MomentIO b # (<*) :: MomentIO a -> MomentIO b -> MomentIO a #
Applicative Cleanup
Instance details Defined in System.Process.Typed Methods pure :: a -> Cleanup a # (<>) :: Cleanup (a -> b) -> Cleanup a -> Cleanup b # liftA2 :: (a -> b -> c) -> Cleanup a -> Cleanup b -> Cleanup c # (>) :: Cleanup a -> Cleanup b -> Cleanup b # (<*) :: Cleanup a -> Cleanup b -> Cleanup a #
Applicative Element
Instance details Defined in Control.Concurrent.Chan.Unagi.NoBlocking.Types Methods pure :: a -> Element a # (<>) :: Element (a -> b) -> Element a -> Element b # liftA2 :: (a -> b -> c) -> Element a -> Element b -> Element c # (>) :: Element a -> Element b -> Element b # (<*) :: Element a -> Element b -> Element a #
Applicative Weigh
Instance details Defined in Weigh Methods pure :: a -> Weigh a # (<>) :: Weigh (a -> b) -> Weigh a -> Weigh b # liftA2 :: (a -> b -> c) -> Weigh a -> Weigh b -> Weigh c # (>) :: Weigh a -> Weigh b -> Weigh b # (<*) :: Weigh a -> Weigh b -> Weigh a #
Applicative P	Since: base-4.5.0.0
Instance details Defined in 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 ((->) a :: * -> *))
Instance details Defined in Data.Constraint Methods ins :: () :- Applicative ((->) a) #
() :=> (Applicative [])
Instance details Defined in Data.Constraint Methods ins :: () :- Applicative [] #
() :=> (Applicative Maybe)
Instance details Defined in Data.Constraint Methods ins :: () :- Applicative Maybe #
() :=> (Applicative IO)
Instance details Defined in Data.Constraint Methods ins :: () :- Applicative IO #
() :=> (Applicative (Either a))
Instance details Defined in Data.Constraint Methods ins :: () :- Applicative (Either a) #
Applicative (Either e)	Since: base-3.0
Instance details Defined in 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 (U1 :: * -> *)	Since: base-4.9.0.0
Instance details Defined in GHC.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 #
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.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) #
Applicative (ST s)	Since: base-4.4.0.0
Instance details Defined in GHC.ST Methods pure :: a -> ST s a # (<>) :: ST s (a -> b) -> ST s a -> ST s b # liftA2 :: (a -> b -> c) -> ST s a -> ST s b -> ST s c # (>) :: ST s a -> ST s b -> ST s b # (<*) :: ST s a -> ST s b -> ST s a #
Applicative (Results s)
Instance details Defined in Text.Earley.Parser.Internal Methods pure :: a -> Results s a # (<>) :: Results s (a -> b) -> Results s a -> Results s b # liftA2 :: (a -> b -> c) -> Results s a -> Results s b -> Results s c # (>) :: Results s a -> Results s b -> Results s b # (<*) :: Results s a -> Results s b -> Results s a #
Applicative (Grammar r)
Instance details Defined in Text.Earley.Grammar Methods pure :: a -> Grammar r a # (<>) :: Grammar r (a -> b) -> Grammar r a -> Grammar r b # liftA2 :: (a -> b -> c) -> Grammar r a -> Grammar r b -> Grammar r c # (>) :: Grammar r a -> Grammar r b -> Grammar r b # (<*) :: Grammar r a -> Grammar r b -> Grammar r a #
Representable f => Applicative (Co f)
Instance details Defined in Data.Functor.Rep Methods pure :: a -> Co f a # (<>) :: Co f (a -> b) -> Co f a -> Co f b # liftA2 :: (a -> b -> c) -> Co f a -> Co f b -> Co f c # (>) :: Co f a -> Co f b -> Co f b # (<*) :: Co f a -> Co f b -> Co f 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 #
Arrow a => Applicative (ArrowMonad a)	Since: base-4.6.0.0
Instance details Defined in 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 (Proxy :: * -> *)	Since: base-4.7.0.0
Instance details Defined in 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 (Parser e)
Instance details Defined in Env.Internal.Parser Methods pure :: a -> Parser e a # (<>) :: Parser e (a -> b) -> Parser e a -> Parser e b # liftA2 :: (a -> b -> c) -> Parser e a -> Parser e b -> Parser e c # (>) :: Parser e a -> Parser e b -> Parser e b # (<*) :: Parser e a -> Parser e b -> Parser e 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 #
Applicative (Fold a)
Instance details Defined in Control.Foldl Methods pure :: a0 -> Fold a a0 # (<>) :: Fold a (a0 -> b) -> Fold a a0 -> Fold a b # liftA2 :: (a0 -> b -> c) -> Fold a a0 -> Fold a b -> Fold a c # (>) :: Fold a a0 -> Fold a b -> Fold a b # (<*) :: Fold a a0 -> Fold a b -> Fold a a0 #
Alternative f => Applicative (Cofree f)
Instance details Defined in Control.Comonad.Cofree Methods pure :: a -> Cofree f a # (<>) :: Cofree f (a -> b) -> Cofree f a -> Cofree f b # liftA2 :: (a -> b -> c) -> Cofree f a -> Cofree f b -> Cofree f c # (>) :: Cofree f a -> Cofree f b -> Cofree f b # (<*) :: Cofree f a -> Cofree f b -> Cofree f a #
Functor f => Applicative (Free f)
Instance details Defined in Control.Monad.Free Methods pure :: a -> Free f a # (<>) :: Free f (a -> b) -> Free f a -> Free f b # liftA2 :: (a -> b -> c) -> Free f a -> Free f b -> Free f c # (>) :: Free f a -> Free f b -> Free f b # (<*) :: Free f a -> Free f b -> Free f a #
Applicative (Ap f)
Instance details Defined in Control.Applicative.Free 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 #
Monad m => Applicative (PropertyT m)
Instance details Defined in Hedgehog.Internal.Property Methods pure :: a -> PropertyT m a # (<>) :: PropertyT m (a -> b) -> PropertyT m a -> PropertyT m b # liftA2 :: (a -> b -> c) -> PropertyT m a -> PropertyT m b -> PropertyT m c # (>) :: PropertyT m a -> PropertyT m b -> PropertyT m b # (<*) :: PropertyT m a -> PropertyT m b -> PropertyT m a #
Monad m => Applicative (TestT m)
Instance details Defined in Hedgehog.Internal.Property Methods pure :: a -> TestT m a # (<>) :: TestT m (a -> b) -> TestT m a -> TestT m b # liftA2 :: (a -> b -> c) -> TestT m a -> TestT m b -> TestT m c # (>) :: TestT m a -> TestT m b -> TestT m b # (<*) :: TestT m a -> TestT m b -> TestT m a #
Monad m => Applicative (GenT m)
Instance details Defined in Hedgehog.Internal.Gen Methods pure :: a -> GenT m a # (<>) :: GenT m (a -> b) -> GenT m a -> GenT m b # liftA2 :: (a -> b -> c) -> GenT m a -> GenT m b -> GenT m c # (>) :: GenT m a -> GenT m b -> GenT m b # (<*) :: GenT m a -> GenT m b -> GenT m a #
Applicative f => Applicative (Yoneda f)
Instance details Defined in Data.Functor.Yoneda Methods pure :: a -> Yoneda f a # (<>) :: Yoneda f (a -> b) -> Yoneda f a -> Yoneda f b # liftA2 :: (a -> b -> c) -> Yoneda f a -> Yoneda f b -> Yoneda f c # (>) :: Yoneda f a -> Yoneda f b -> Yoneda f b # (<*) :: Yoneda f a -> Yoneda f b -> Yoneda f a #
Applicative (ReifiedGetter s)
Instance details Defined in Control.Lens.Reified Methods pure :: a -> ReifiedGetter s a # (<>) :: ReifiedGetter s (a -> b) -> ReifiedGetter s a -> ReifiedGetter s b # liftA2 :: (a -> b -> c) -> ReifiedGetter s a -> ReifiedGetter s b -> ReifiedGetter s c # (>) :: ReifiedGetter s a -> ReifiedGetter s b -> ReifiedGetter s b # (<*) :: ReifiedGetter s a -> ReifiedGetter s b -> ReifiedGetter s a #
Applicative (ReifiedFold s)
Instance details Defined in Control.Lens.Reified Methods pure :: a -> ReifiedFold s a # (<>) :: ReifiedFold s (a -> b) -> ReifiedFold s a -> ReifiedFold s b # liftA2 :: (a -> b -> c) -> ReifiedFold s a -> ReifiedFold s b -> ReifiedFold s c # (>) :: ReifiedFold s a -> ReifiedFold s b -> ReifiedFold s b # (<*) :: ReifiedFold s a -> ReifiedFold s b -> ReifiedFold s a #
Applicative f => Applicative (Indexing f)
Instance details Defined in Control.Lens.Internal.Indexed Methods pure :: a -> Indexing f a # (<>) :: Indexing f (a -> b) -> Indexing f a -> Indexing f b # liftA2 :: (a -> b -> c) -> Indexing f a -> Indexing f b -> Indexing f c # (>) :: Indexing f a -> Indexing f b -> Indexing f b # (<*) :: Indexing f a -> Indexing f b -> Indexing f a #
Applicative f => Applicative (Indexing64 f)
Instance details Defined in Control.Lens.Internal.Indexed Methods pure :: a -> Indexing64 f a # (<>) :: Indexing64 f (a -> b) -> Indexing64 f a -> Indexing64 f b # liftA2 :: (a -> b -> c) -> Indexing64 f a -> Indexing64 f b -> Indexing64 f c # (>) :: Indexing64 f a -> Indexing64 f b -> Indexing64 f b # (<*) :: Indexing64 f a -> Indexing64 f b -> Indexing64 f a #
Monad m => Applicative (ListT m)
Instance details Defined in List.Transformer Methods pure :: a -> ListT m a # (<>) :: ListT m (a -> b) -> ListT m a -> ListT m b # liftA2 :: (a -> b -> c) -> ListT m a -> ListT m b -> ListT m c # (>) :: ListT m a -> ListT m b -> ListT m b # (<*) :: ListT m a -> ListT m b -> ListT m a #
Applicative (LogicT f)
Instance details Defined in Control.Monad.Logic Methods pure :: a -> LogicT f a # (<>) :: LogicT f (a -> b) -> LogicT f a -> LogicT f b # liftA2 :: (a -> b -> c) -> LogicT f a -> LogicT f b -> LogicT f c # (>) :: LogicT f a -> LogicT f b -> LogicT f b # (<*) :: LogicT f a -> LogicT f b -> LogicT f a #
(Applicative (Rep p), Representable p) => Applicative (Prep p)
Instance details Defined in Data.Profunctor.Rep Methods pure :: a -> Prep p a # (<>) :: Prep p (a -> b) -> Prep p a -> Prep p b # liftA2 :: (a -> b -> c) -> Prep p a -> Prep p b -> Prep p c # (>) :: Prep p a -> Prep p b -> Prep p b # (<*) :: Prep p a -> Prep p b -> Prep p a #
Applicative f => Applicative (WrappedApplicative f)
Instance details Defined in Data.Functor.Bind.Class Methods pure :: a -> WrappedApplicative f a # (<>) :: WrappedApplicative f (a -> b) -> WrappedApplicative f a -> WrappedApplicative f b # liftA2 :: (a -> b -> c) -> WrappedApplicative f a -> WrappedApplicative f b -> WrappedApplicative f c # (>) :: WrappedApplicative f a -> WrappedApplicative f b -> WrappedApplicative f b # (<*) :: WrappedApplicative f a -> WrappedApplicative f b -> WrappedApplicative f a #
Apply f => Applicative (MaybeApply f)
Instance details Defined in Data.Functor.Bind.Class Methods pure :: a -> MaybeApply f a # (<>) :: MaybeApply f (a -> b) -> MaybeApply f a -> MaybeApply f b # liftA2 :: (a -> b -> c) -> MaybeApply f a -> MaybeApply f b -> MaybeApply f c # (>) :: MaybeApply f a -> MaybeApply f b -> MaybeApply f b # (<*) :: MaybeApply f a -> MaybeApply f b -> MaybeApply f 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 #
MonadUnliftIO m => Applicative (Concurrently m)	Since: unliftio-0.1.0.0
Instance details Defined in UnliftIO.Async Methods pure :: a -> Concurrently m a # (<>) :: Concurrently m (a -> b) -> Concurrently m a -> Concurrently m b # liftA2 :: (a -> b -> c) -> Concurrently m a -> Concurrently m b -> Concurrently m c # (>) :: Concurrently m a -> Concurrently m b -> Concurrently m b # (<*) :: Concurrently m a -> Concurrently m b -> Concurrently 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 #
Applicative (IncrementalDecoder s)
Instance details Defined in Codec.CBOR.Read Methods pure :: a -> IncrementalDecoder s a # (<>) :: IncrementalDecoder s (a -> b) -> IncrementalDecoder s a -> IncrementalDecoder s b # liftA2 :: (a -> b -> c) -> IncrementalDecoder s a -> IncrementalDecoder s b -> IncrementalDecoder s c # (>) :: IncrementalDecoder s a -> IncrementalDecoder s b -> IncrementalDecoder s b # (<*) :: IncrementalDecoder s a -> IncrementalDecoder s b -> IncrementalDecoder s a #
Class (Functor f) (Applicative f)
Instance details Defined in Data.Constraint Methods cls :: Applicative f :- Functor f #
Class (Applicative f) (Monad f)
Instance details Defined in Data.Constraint Methods cls :: Monad f :- Applicative f #
Class (Applicative f) (Alternative f)
Instance details Defined in Data.Constraint Methods cls :: Alternative f :- Applicative f #
(Monad m) :=> (Applicative (WrappedMonad m))
Instance details Defined in Data.Constraint Methods ins :: Monad m :- Applicative (WrappedMonad m) #
(Monoid a) :=> (Applicative ((,) a))
Instance details Defined in Data.Constraint Methods ins :: Monoid a :- Applicative ((,) a) #
(Monoid a) :=> (Applicative (Const a :: * -> *))
Instance details Defined in Data.Constraint Methods ins :: Monoid a :- Applicative (Const a) #
Applicative f => Applicative (Rec1 f)	Since: base-4.9.0.0
Instance details Defined in GHC.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 (Results s t)
Instance details Defined in Text.Earley.Generator.Internal Methods pure :: a -> Results s t a # (<>) :: Results s t (a -> b) -> Results s t a -> Results s t b # liftA2 :: (a -> b -> c) -> Results s t a -> Results s t b -> Results s t c # (>) :: Results s t a -> Results s t b -> Results s t b # (<*) :: Results s t a -> Results s t b -> Results s t a #
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 #
Monoid m => Applicative (Const m :: * -> *)	Since: base-2.0.1
Instance details Defined in 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 (Alt f)
Instance details Defined in 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 #
Biapplicative p => Applicative (Join p)
Instance details Defined in Data.Bifunctor.Join Methods pure :: a -> Join p a # (<>) :: Join p (a -> b) -> Join p a -> Join p b # liftA2 :: (a -> b -> c) -> Join p a -> Join p b -> Join p c # (>) :: Join p a -> Join p b -> Join p b # (<*) :: Join p a -> Join p b -> Join p a #
Biapplicative p => Applicative (Fix p)
Instance details Defined in Data.Bifunctor.Fix Methods pure :: a -> Fix p a # (<>) :: Fix p (a -> b) -> Fix p a -> Fix p b # liftA2 :: (a -> b -> c) -> Fix p a -> Fix p b -> Fix p c # (>) :: Fix p a -> Fix p b -> Fix p b # (<*) :: Fix p a -> Fix p b -> Fix p 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 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 #
(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 #
Monad m => Applicative (GT m g)
Instance details Defined in Data.Graph.Inductive.Query.Monad Methods pure :: a -> GT m g a # (<>) :: GT m g (a -> b) -> GT m g a -> GT m g b # liftA2 :: (a -> b -> c) -> GT m g a -> GT m g b -> GT m g c # (>) :: GT m g a -> GT m g b -> GT m g b # (<*) :: GT m g a -> GT m g b -> GT m g a #
Applicative m => Applicative (FoldM m a)
Instance details Defined in Control.Foldl Methods pure :: a0 -> FoldM m a a0 # (<>) :: FoldM m a (a0 -> b) -> FoldM m a a0 -> FoldM m a b # liftA2 :: (a0 -> b -> c) -> FoldM m a a0 -> FoldM m a b -> FoldM m a c # (>) :: FoldM m a a0 -> FoldM m a b -> FoldM m a b # (<*) :: FoldM m a a0 -> FoldM m a b -> FoldM m a a0 #
(Functor f, Monad m) => Applicative (FreeT f m)
Instance details Defined in Control.Monad.Trans.Free Methods pure :: a -> FreeT f m a # (<>) :: FreeT f m (a -> b) -> FreeT f m a -> FreeT f m b # liftA2 :: (a -> b -> c) -> FreeT f m a -> FreeT f m b -> FreeT f m c # (>) :: FreeT f m a -> FreeT f m b -> FreeT f m b # (<*) :: FreeT f m a -> FreeT f m b -> FreeT f m a #
(Alternative f, Applicative w) => Applicative (CofreeT f w)
Instance details Defined in Control.Comonad.Trans.Cofree Methods pure :: a -> CofreeT f w a # (<>) :: CofreeT f w (a -> b) -> CofreeT f w a -> CofreeT f w b # liftA2 :: (a -> b -> c) -> CofreeT f w a -> CofreeT f w b -> CofreeT f w c # (>) :: CofreeT f w a -> CofreeT f w b -> CofreeT f w b # (<*) :: CofreeT f w a -> CofreeT f w b -> CofreeT f w a #
(Applicative f, Applicative g) => Applicative (Day f g)
Instance details Defined in Data.Functor.Day Methods pure :: a -> Day f g a # (<>) :: Day f g (a -> b) -> Day f g a -> Day f g b # liftA2 :: (a -> b -> c) -> Day f g a -> Day f g b -> Day f g c # (>) :: Day f g a -> Day f g b -> Day f g b # (<*) :: Day f g a -> Day f g b -> Day f g a #
(Functor m, Monad m) => Applicative (ErrorT e m)
Instance details Defined in Control.Monad.Trans.Error Methods pure :: a -> ErrorT e m a # (<>) :: ErrorT e m (a -> b) -> ErrorT e m a -> ErrorT e m b # liftA2 :: (a -> b -> c) -> ErrorT e m a -> ErrorT e m b -> ErrorT e m c # (>) :: ErrorT e m a -> ErrorT e m b -> ErrorT e m b # (<*) :: ErrorT e m a -> ErrorT e m b -> ErrorT e 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 #
Applicative (Mafic a b)
Instance details Defined in Control.Lens.Internal.Magma Methods pure :: a0 -> Mafic a b a0 # (<>) :: Mafic a b (a0 -> b0) -> Mafic a b a0 -> Mafic a b b0 # liftA2 :: (a0 -> b0 -> c) -> Mafic a b a0 -> Mafic a b b0 -> Mafic a b c # (>) :: Mafic a b a0 -> Mafic a b b0 -> Mafic a b b0 # (<*) :: Mafic a b a0 -> Mafic a b b0 -> Mafic a b a0 #
Applicative (Indexed i a)
Instance details Defined in Control.Lens.Internal.Indexed Methods pure :: a0 -> Indexed i a a0 # (<>) :: Indexed i a (a0 -> b) -> Indexed i a a0 -> Indexed i a b # liftA2 :: (a0 -> b -> c) -> Indexed i a a0 -> Indexed i a b -> Indexed i a c # (>) :: Indexed i a a0 -> Indexed i a b -> Indexed i a b # (<*) :: Indexed i a a0 -> Indexed i a b -> Indexed i a a0 #
(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 #
Applicative (STE e s)
Instance details Defined in Control.Monad.STE.Internal Methods pure :: a -> STE e s a # (<>) :: STE e s (a -> b) -> STE e s a -> STE e s b # liftA2 :: (a -> b -> c) -> STE e s a -> STE e s b -> STE e s c # (>) :: STE e s a -> STE e s b -> STE e s b # (<*) :: STE e s a -> STE e s b -> STE e s 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 #
(Profunctor p, Arrow p) => Applicative (Closure p a)
Instance details Defined in Data.Profunctor.Closed Methods pure :: a0 -> Closure p a a0 # (<>) :: Closure p a (a0 -> b) -> Closure p a a0 -> Closure p a b # liftA2 :: (a0 -> b -> c) -> Closure p a a0 -> Closure p a b -> Closure p a c # (>) :: Closure p a a0 -> Closure p a b -> Closure p a b # (<*) :: Closure p a a0 -> Closure p a b -> Closure p a a0 #
(Profunctor p, Arrow p) => Applicative (Tambara p a)
Instance details Defined in Data.Profunctor.Strong Methods pure :: a0 -> Tambara p a a0 # (<>) :: Tambara p a (a0 -> b) -> Tambara p a a0 -> Tambara p a b # liftA2 :: (a0 -> b -> c) -> Tambara p a a0 -> Tambara p a b -> Tambara p a c # (>) :: Tambara p a a0 -> Tambara p a b -> Tambara p a b # (<*) :: Tambara p a a0 -> Tambara p a b -> Tambara p a a0 #
Applicative f => Applicative (Star f a)
Instance details Defined in Data.Profunctor.Types Methods pure :: a0 -> Star f a a0 # (<>) :: Star f a (a0 -> b) -> Star f a a0 -> Star f a b # liftA2 :: (a0 -> b -> c) -> Star f a a0 -> Star f a b -> Star f a c # (>) :: Star f a a0 -> Star f a b -> Star f a b # (<*) :: Star f a a0 -> Star f a b -> Star f a a0 #
Applicative (Costar f a)
Instance details Defined in Data.Profunctor.Types Methods pure :: a0 -> Costar f a a0 # (<>) :: Costar f a (a0 -> b) -> Costar f a a0 -> Costar f a b # liftA2 :: (a0 -> b -> c) -> Costar f a a0 -> Costar f a b -> Costar f a c # (>) :: Costar f a a0 -> Costar f a b -> Costar f a b # (<*) :: Costar f a a0 -> Costar f a b -> Costar f a a0 #
Applicative f => Applicative (Static f a)
Instance details Defined in Data.Semigroupoid.Static Methods pure :: a0 -> Static f a a0 # (<>) :: Static f a (a0 -> b) -> Static f a a0 -> Static f a b # liftA2 :: (a0 -> b -> c) -> Static f a a0 -> Static f a b -> Static f a c # (>) :: Static f a a0 -> Static f a b -> Static f a b # (<*) :: Static f a a0 -> Static f a b -> Static f a a0 #
Applicative (Tagged s)
Instance details Defined in Data.Tagged Methods pure :: a -> Tagged s a # (<>) :: Tagged s (a -> b) -> Tagged s a -> Tagged s b # liftA2 :: (a -> b -> c) -> Tagged s a -> Tagged s b -> Tagged s c # (>) :: Tagged s a -> Tagged s b -> Tagged s b # (<*) :: Tagged s a -> Tagged s b -> Tagged s a #
(Functor m, Monad m) => Applicative (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.CPS.Internal 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 m => Applicative (Holes t m)
Instance details Defined in Control.Lens.Traversal Methods pure :: a -> Holes t m a # (<>) :: Holes t m (a -> b) -> Holes t m a -> Holes t m b # liftA2 :: (a -> b -> c) -> Holes t m a -> Holes t m b -> Holes t m c # (>) :: Holes t m a -> Holes t m b -> Holes t m b # (<*) :: Holes t m a -> Holes t m b -> Holes t m a #
Applicative ((->) a :: * -> *)	Since: base-2.1
Instance details Defined in GHC.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 #
(Applicative f, Applicative g) => Applicative (f :*: g)	Since: base-4.9.0.0
Instance details Defined in GHC.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 (Prod r e t)
Instance details Defined in Text.Earley.Grammar Methods pure :: a -> Prod r e t a # (<>) :: Prod r e t (a -> b) -> Prod r e t a -> Prod r e t b # liftA2 :: (a -> b -> c) -> Prod r e t a -> Prod r e t b -> Prod r e t c # (>) :: Prod r e t a -> Prod r e t b -> Prod r e t b # (<*) :: Prod r e t a -> Prod r e t b -> Prod r e t a #
(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 #
Applicative (Cokleisli w a)
Instance details Defined in Control.Comonad Methods pure :: a0 -> Cokleisli w a a0 # (<>) :: Cokleisli w a (a0 -> b) -> Cokleisli w a a0 -> Cokleisli w a b # liftA2 :: (a0 -> b -> c) -> Cokleisli w a a0 -> Cokleisli w a b -> Cokleisli w a c # (>) :: Cokleisli w a a0 -> Cokleisli w a b -> Cokleisli w a b # (<*) :: Cokleisli w a a0 -> Cokleisli w a b -> Cokleisli w a a0 #
(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 (Molten i a b)
Instance details Defined in Control.Lens.Internal.Magma Methods pure :: a0 -> Molten i a b a0 # (<>) :: Molten i a b (a0 -> b0) -> Molten i a b a0 -> Molten i a b b0 # liftA2 :: (a0 -> b0 -> c) -> Molten i a b a0 -> Molten i a b b0 -> Molten i a b c # (>) :: Molten i a b a0 -> Molten i a b b0 -> Molten i a b b0 # (<*) :: Molten i a b a0 -> Molten i a b b0 -> Molten i a b a0 #
Applicative (Bazaar p a b)
Instance details Defined in Control.Lens.Internal.Bazaar Methods pure :: a0 -> Bazaar p a b a0 # (<>) :: Bazaar p a b (a0 -> b0) -> Bazaar p a b a0 -> Bazaar p a b b0 # liftA2 :: (a0 -> b0 -> c) -> Bazaar p a b a0 -> Bazaar p a b b0 -> Bazaar p a b c # (>) :: Bazaar p a b a0 -> Bazaar p a b b0 -> Bazaar p a b b0 # (<*) :: Bazaar p a b a0 -> Bazaar p a b b0 -> Bazaar p a b a0 #
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 #
Stream s => Applicative (ParsecT e s m)	`pure` returns a parser that succeeds without consuming input.
Instance details Defined in Text.Megaparsec.Internal Methods pure :: a -> ParsecT e s m a # (<>) :: ParsecT e s m (a -> b) -> ParsecT e s m a -> ParsecT e s m b # liftA2 :: (a -> b -> c) -> ParsecT e s m a -> ParsecT e s m b -> ParsecT e s m c # (>) :: ParsecT e s m a -> ParsecT e s m b -> ParsecT e s m b # (<*) :: ParsecT e s m a -> ParsecT e s m b -> ParsecT e s m 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 #
Applicative f => Applicative (M1 i c f)	Since: base-4.9.0.0
Instance details Defined in GHC.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 #
(Applicative f, Applicative g) => Applicative (f :.: g)	Since: base-4.9.0.0
Instance details Defined in GHC.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 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 (TakingWhile p f a b)
Instance details Defined in Control.Lens.Internal.Magma Methods pure :: a0 -> TakingWhile p f a b a0 # (<>) :: TakingWhile p f a b (a0 -> b0) -> TakingWhile p f a b a0 -> TakingWhile p f a b b0 # liftA2 :: (a0 -> b0 -> c) -> TakingWhile p f a b a0 -> TakingWhile p f a b b0 -> TakingWhile p f a b c # (>) :: TakingWhile p f a b a0 -> TakingWhile p f a b b0 -> TakingWhile p f a b b0 # (<*) :: TakingWhile p f a b a0 -> TakingWhile p f a b b0 -> TakingWhile p f a b a0 #
Applicative (BazaarT p g a b)
Instance details Defined in Control.Lens.Internal.Bazaar Methods pure :: a0 -> BazaarT p g a b a0 # (<>) :: BazaarT p g a b (a0 -> b0) -> BazaarT p g a b a0 -> BazaarT p g a b b0 # liftA2 :: (a0 -> b0 -> c) -> BazaarT p g a b a0 -> BazaarT p g a b b0 -> BazaarT p g a b c # (>) :: BazaarT p g a b a0 -> BazaarT p g a b b0 -> BazaarT p g a b b0 # (<*) :: BazaarT p g a b a0 -> BazaarT p g a b b0 -> BazaarT p g a b a0 #
Reifies s (ReifiedApplicative f) => Applicative (ReflectedApplicative f s)
Instance details Defined in Data.Reflection Methods pure :: a -> ReflectedApplicative f s a # (<>) :: ReflectedApplicative f s (a -> b) -> ReflectedApplicative f s a -> ReflectedApplicative f s b # liftA2 :: (a -> b -> c) -> ReflectedApplicative f s a -> ReflectedApplicative f s b -> ReflectedApplicative f s c # (>) :: ReflectedApplicative f s a -> ReflectedApplicative f s b -> ReflectedApplicative f s b # (<*) :: ReflectedApplicative f s a -> ReflectedApplicative f s b -> ReflectedApplicative f s a #

between :: Applicative m => m open -> m close -> m a -> m a #

between open close p parses open, followed by p and close. Returns the value returned by p.

braces = between (symbol "{") (symbol "}")

filterM :: Applicative m => (a -> m Bool) -> [a] -> m [a] #

This generalizes the list-based filter function.

forever :: Applicative f => f a -> f b #

forever act repeats the action infinitely.

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

Lift a ternary function to actions.

replicateM :: Applicative m => Int -> m a -> m [a] #

replicateM n act performs the action n times, gathering the results.

replicateM_ :: Applicative m => Int -> m a -> m () #

Like replicateM, but discards the result.

unless :: Applicative f => Bool -> f () -> f () #

The reverse of when.

when :: Applicative f => Bool -> f () -> f () #

Conditional execution of Applicative expressions. For example,

when debug (putStrLn "Debugging")

will output the string Debugging if the Boolean value debug is True, and otherwise do nothing.

zipWithM :: Applicative m => (a -> b -> m c) -> [a] -> [b] -> m [c] #

The zipWithM function generalizes zipWith to arbitrary applicative functors.

zipWithM_ :: Applicative m => (a -> b -> m c) -> [a] -> [b] -> m () #

zipWithM_ is the extension of zipWithM which ignores the final result.

Alternative

class Applicative f => Alternative (f :: * -> *) 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 []
```

Minimal complete definition

empty, (<|>)

Methods

empty :: f a #

The identity of <|>

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

An associative binary operation

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

Zero or more.

Instances

Alternative []	Since: base-2.1
Instance details Defined in GHC.Base Methods empty :: [a] # (<\|>) :: [a] -> [a] -> [a] # some :: [a] -> [[a]] # many :: [a] -> [[a]] #
Alternative Maybe	Since: base-2.1
Instance details Defined in GHC.Base Methods empty :: Maybe a # (<\|>) :: Maybe a -> Maybe a -> Maybe a # some :: Maybe a -> Maybe [a] # many :: Maybe a -> Maybe [a] #
Alternative IO	Since: base-4.9.0.0
Instance details Defined in GHC.Base Methods empty :: IO a # (<\|>) :: IO a -> IO a -> IO a # some :: IO a -> IO [a] # many :: IO a -> IO [a] #
Alternative IResult
Instance details Defined in Data.Aeson.Types.Internal Methods empty :: IResult a # (<\|>) :: IResult a -> IResult a -> IResult a # some :: IResult a -> IResult [a] # many :: IResult a -> IResult [a] #
Alternative Result
Instance details Defined in Data.Aeson.Types.Internal Methods empty :: Result a # (<\|>) :: Result a -> Result a -> Result a # some :: Result a -> Result [a] # many :: Result a -> Result [a] #
Alternative Parser
Instance details Defined in Data.Aeson.Types.Internal Methods empty :: Parser a # (<\|>) :: Parser a -> Parser a -> Parser a # some :: Parser a -> Parser [a] # many :: Parser a -> Parser [a] #
Alternative Concurrently
Instance details Defined in Control.Concurrent.Async Methods empty :: Concurrently a # (<\|>) :: Concurrently a -> Concurrently a -> Concurrently a # some :: Concurrently a -> Concurrently [a] # many :: Concurrently a -> Concurrently [a] #
Alternative Option	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods empty :: Option a # (<\|>) :: Option a -> Option a -> Option a # some :: Option a -> Option [a] # many :: Option a -> Option [a] #
Alternative ZipList	Since: base-4.11.0.0
Instance details Defined in Control.Applicative Methods empty :: ZipList a # (<\|>) :: ZipList a -> ZipList a -> ZipList a # some :: ZipList a -> ZipList [a] # many :: ZipList a -> ZipList [a] #
Alternative STM	Since: base-4.8.0.0
Instance details Defined in GHC.Conc.Sync Methods empty :: STM a # (<\|>) :: STM a -> STM a -> STM a # some :: STM a -> STM [a] # many :: STM a -> STM [a] #
Alternative ReadPrec	Since: base-4.6.0.0
Instance details Defined in Text.ParserCombinators.ReadPrec Methods empty :: ReadPrec a # (<\|>) :: ReadPrec a -> ReadPrec a -> ReadPrec a # some :: ReadPrec a -> ReadPrec [a] # many :: ReadPrec a -> ReadPrec [a] #
Alternative ReadP	Since: base-4.6.0.0
Instance details Defined in Text.ParserCombinators.ReadP Methods empty :: ReadP a # (<\|>) :: ReadP a -> ReadP a -> ReadP a # some :: ReadP a -> ReadP [a] # many :: ReadP a -> ReadP [a] #
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 DList
Instance details Defined in Data.DList Methods empty :: DList a # (<\|>) :: DList a -> DList a -> DList a # some :: DList a -> DList [a] # many :: DList a -> DList [a] #
Alternative Vector
Instance details Defined in Data.Vector Methods empty :: Vector a # (<\|>) :: Vector a -> Vector a -> Vector a # some :: Vector a -> Vector [a] # many :: Vector a -> Vector [a] #
Alternative ReadM
Instance details Defined in Options.Applicative.Types Methods empty :: ReadM a # (<\|>) :: ReadM a -> ReadM a -> ReadM a # some :: ReadM a -> ReadM [a] # many :: ReadM a -> ReadM [a] #
Alternative Parser
Instance details Defined in Options.Applicative.Types Methods empty :: Parser a # (<\|>) :: Parser a -> Parser a -> Parser a # some :: Parser a -> Parser [a] # many :: Parser a -> Parser [a] #
Alternative SmallArray
Instance details Defined in Data.Primitive.SmallArray Methods empty :: SmallArray a # (<\|>) :: SmallArray a -> SmallArray a -> SmallArray a # some :: SmallArray a -> SmallArray [a] # many :: SmallArray a -> SmallArray [a] #
Alternative Array
Instance details Defined in Data.Primitive.Array Methods empty :: Array a # (<\|>) :: Array a -> Array a -> Array a # some :: Array a -> Array [a] # many :: Array a -> Array [a] #
Alternative Element
Instance details Defined in Control.Concurrent.Chan.Unagi.NoBlocking.Types Methods empty :: Element a # (<\|>) :: Element a -> Element a -> Element a # some :: Element a -> Element [a] # many :: Element a -> Element [a] #
Alternative P	Since: base-4.5.0.0
Instance details Defined in Text.ParserCombinators.ReadP Methods empty :: P a # (<\|>) :: P a -> P a -> P a # some :: P a -> P [a] # many :: P a -> P [a] #
() :=> (Alternative [])
Instance details Defined in Data.Constraint Methods ins :: () :- Alternative [] #
() :=> (Alternative Maybe)
Instance details Defined in Data.Constraint Methods ins :: () :- Alternative Maybe #
Alternative (U1 :: * -> *)	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods empty :: U1 a # (<\|>) :: U1 a -> U1 a -> U1 a # some :: U1 a -> U1 [a] # many :: U1 a -> U1 [a] #
Alternative (Results s)
Instance details Defined in Text.Earley.Parser.Internal Methods empty :: Results s a # (<\|>) :: Results s a -> Results s a -> Results s a # some :: Results s a -> Results s [a] # many :: Results s a -> Results s [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 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 :: * -> *)	Since: base-4.9.0.0
Instance details Defined in Data.Proxy Methods empty :: Proxy a # (<\|>) :: Proxy a -> Proxy a -> Proxy a # some :: Proxy a -> Proxy [a] # many :: Proxy a -> Proxy [a] #
Alternative (Parser e)
Instance details Defined in Env.Internal.Parser Methods empty :: Parser e a # (<\|>) :: Parser e a -> Parser e a -> Parser e a # some :: Parser e a -> Parser e [a] # many :: Parser e a -> Parser e [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] #
Alternative v => Alternative (Free v)	This violates the Alternative laws, handle with care.
Instance details Defined in Control.Monad.Free Methods empty :: Free v a # (<\|>) :: Free v a -> Free v a -> Free v a # some :: Free v a -> Free v [a] # many :: Free v a -> Free v [a] #
MonadPlus m => Alternative (PropertyT m)
Instance details Defined in Hedgehog.Internal.Property Methods empty :: PropertyT m a # (<\|>) :: PropertyT m a -> PropertyT m a -> PropertyT m a # some :: PropertyT m a -> PropertyT m [a] # many :: PropertyT m a -> PropertyT m [a] #
Monad m => Alternative (GenT m)
Instance details Defined in Hedgehog.Internal.Gen Methods empty :: GenT m a # (<\|>) :: GenT m a -> GenT m a -> GenT m a # some :: GenT m a -> GenT m [a] # many :: GenT m a -> GenT m [a] #
Alternative f => Alternative (Yoneda f)
Instance details Defined in Data.Functor.Yoneda Methods empty :: Yoneda f a # (<\|>) :: Yoneda f a -> Yoneda f a -> Yoneda f a # some :: Yoneda f a -> Yoneda f [a] # many :: Yoneda f a -> Yoneda f [a] #
Alternative (ReifiedFold s)
Instance details Defined in Control.Lens.Reified Methods empty :: ReifiedFold s a # (<\|>) :: ReifiedFold s a -> ReifiedFold s a -> ReifiedFold s a # some :: ReifiedFold s a -> ReifiedFold s [a] # many :: ReifiedFold s a -> ReifiedFold s [a] #
Monad m => Alternative (ListT m)
Instance details Defined in List.Transformer Methods empty :: ListT m a # (<\|>) :: ListT m a -> ListT m a -> ListT m a # some :: ListT m a -> ListT m [a] # many :: ListT m a -> ListT m [a] #
Alternative (LogicT f)
Instance details Defined in Control.Monad.Logic Methods empty :: LogicT f a # (<\|>) :: LogicT f a -> LogicT f a -> LogicT f a # some :: LogicT f a -> LogicT f [a] # many :: LogicT f a -> LogicT f [a] #
Alternative f => Alternative (WrappedApplicative f)
Instance details Defined in Data.Functor.Bind.Class Methods empty :: WrappedApplicative f a # (<\|>) :: WrappedApplicative f a -> WrappedApplicative f a -> WrappedApplicative f a # some :: WrappedApplicative f a -> WrappedApplicative f [a] # many :: WrappedApplicative f a -> WrappedApplicative f [a] #
MonadUnliftIO m => Alternative (Concurrently m)	Since: unliftio-0.1.0.0
Instance details Defined in UnliftIO.Async Methods empty :: Concurrently m a # (<\|>) :: Concurrently m a -> Concurrently m a -> Concurrently m a # some :: Concurrently m a -> Concurrently m [a] # many :: Concurrently m a -> Concurrently m [a] #
Class (Applicative f) (Alternative f)
Instance details Defined in Data.Constraint Methods cls :: Alternative f :- Applicative f #
(MonadPlus m) :=> (Alternative (WrappedMonad m))
Instance details Defined in Data.Constraint Methods ins :: MonadPlus m :- Alternative (WrappedMonad m) #
Alternative f => Alternative (Rec1 f)	Since: base-4.9.0.0
Instance details Defined in GHC.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 (Results t s)
Instance details Defined in Text.Earley.Generator.Internal Methods empty :: Results t s a # (<\|>) :: Results t s a -> Results t s a -> Results t s a # some :: Results t s a -> Results t s [a] # many :: Results t s a -> Results t s [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 f => Alternative (Alt f)
Instance details Defined in 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] #
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] #
(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] #
(Functor f, MonadPlus m) => Alternative (FreeT f m)
Instance details Defined in Control.Monad.Trans.Free Methods empty :: FreeT f m a # (<\|>) :: FreeT f m a -> FreeT f m a -> FreeT f m a # some :: FreeT f m a -> FreeT f m [a] # many :: FreeT f m a -> FreeT f m [a] #
(Functor m, Monad m, Error e) => Alternative (ErrorT e m)
Instance details Defined in Control.Monad.Trans.Error Methods empty :: ErrorT e m a # (<\|>) :: ErrorT e m a -> ErrorT e m a -> ErrorT e m a # some :: ErrorT e m a -> ErrorT e m [a] # many :: ErrorT e m a -> ErrorT e m [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] #
(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] #
(Profunctor p, ArrowPlus p) => Alternative (Closure p a)
Instance details Defined in Data.Profunctor.Closed Methods empty :: Closure p a a0 # (<\|>) :: Closure p a a0 -> Closure p a a0 -> Closure p a a0 # some :: Closure p a a0 -> Closure p a [a0] # many :: Closure p a a0 -> Closure p a [a0] #
(Profunctor p, ArrowPlus p) => Alternative (Tambara p a)
Instance details Defined in Data.Profunctor.Strong Methods empty :: Tambara p a a0 # (<\|>) :: Tambara p a a0 -> Tambara p a a0 -> Tambara p a a0 # some :: Tambara p a a0 -> Tambara p a [a0] # many :: Tambara p a a0 -> Tambara p a [a0] #
Alternative f => Alternative (Star f a)
Instance details Defined in Data.Profunctor.Types Methods empty :: Star f a a0 # (<\|>) :: Star f a a0 -> Star f a a0 -> Star f a a0 # some :: Star f a a0 -> Star f a [a0] # many :: Star f a a0 -> Star f a [a0] #
(Functor m, MonadPlus m) => Alternative (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.CPS.Internal 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] #
Class (Monad f, Alternative f) (MonadPlus f)
Instance details Defined in Data.Constraint Methods cls :: MonadPlus f :- (Monad f, Alternative f) #
(Alternative f, Alternative g) => Alternative (f :*: g)	Since: base-4.9.0.0
Instance details Defined in GHC.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 (Prod r e t)
Instance details Defined in Text.Earley.Grammar Methods empty :: Prod r e t a # (<\|>) :: Prod r e t a -> Prod r e t a -> Prod r e t a # some :: Prod r e t a -> Prod r e t [a] # many :: Prod r e t a -> Prod r e t [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 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] #
(Ord e, Stream s) => Alternative (ParsecT e s m)	`empty` is a parser that fails without consuming input.
Instance details Defined in Text.Megaparsec.Internal Methods empty :: ParsecT e s m a # (<\|>) :: ParsecT e s m a -> ParsecT e s m a -> ParsecT e s m a # some :: ParsecT e s m a -> ParsecT e s m [a] # many :: ParsecT e s m a -> ParsecT e s m [a] #
Alternative f => Alternative (M1 i c f)	Since: base-4.9.0.0
Instance details Defined in GHC.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] #
(Alternative f, Applicative g) => Alternative (f :.: g)	Since: base-4.9.0.0
Instance details Defined in GHC.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] #

endBy :: Alternative m => m a -> m sep -> m [a] #

endBy p sep parses zero or more occurrences of p, separated and ended by sep. Returns a list of values returned by p.

cStatements = cStatement `endBy` semicolon

endBy1 :: Alternative m => m a -> m sep -> m (NonEmpty a) #

endBy1 p sep parses one or more occurrences of p, separated and ended by sep. Returns a non-empty list of values returned by p.

guard :: Alternative f => Bool -> f () #

Conditional failure of Alternative computations. Defined by

guard True  = pure ()
guard False = empty

Examples

Expand

Common uses of guard include conditionally signaling an error in an error monad and conditionally rejecting the current choice in an Alternative-based parser.

As an example of signaling an error in the error monad Maybe, consider a safe division function safeDiv x y that returns Nothing when the denominator y is zero and Just (x `div` y) otherwise. For example:

>>> safeDiv 4 0
Nothing
>>> safeDiv 4 2
Just 2

A definition of safeDiv using guards, but not guard:

safeDiv :: Int -> Int -> Maybe Int
safeDiv x y | y /= 0    = Just (x `div` y)
            | otherwise = Nothing

A definition of safeDiv using guard and Monad do-notation:

safeDiv :: Int -> Int -> Maybe Int
safeDiv x y = do
  guard (y /= 0)
  return (x `div` y)

manyTill :: Alternative m => m a -> m end -> m [a] #

manyTill p end applies parser p zero or more times until parser end succeeds. Returns the list of values returned by p.

Newtypes

newtype Alt (f :: k -> *) (a :: k) :: forall k. (k -> *) -> k -> * #

Monoid under <|>.

Since: base-4.8.0.0

Constructors

Alt
Fields getAlt :: f a

Instances

Generic1 (Alt f :: k -> *)
Instance details Defined in Data.Semigroup.Internal Associated Types type Rep1 (Alt f) :: k -> * # Methods from1 :: Alt f a -> Rep1 (Alt f) a # to1 :: Rep1 (Alt f) a -> Alt f a #
Monad f => Monad (Alt f)
Instance details Defined in Data.Semigroup.Internal Methods (>>=) :: Alt f a -> (a -> Alt f b) -> Alt f b # (>>) :: Alt f a -> Alt f b -> Alt f b # return :: a -> Alt f a # fail :: String -> Alt f a #
Functor f => Functor (Alt f)
Instance details Defined in Data.Semigroup.Internal Methods fmap :: (a -> b) -> Alt f a -> Alt f b # (<$) :: a -> Alt f b -> Alt f a #
MonadFix f => MonadFix (Alt f)	Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Alt f a) -> Alt f a #
Applicative f => Applicative (Alt f)
Instance details Defined in Data.Semigroup.Internal Methods pure :: a -> Alt f a # (<>) :: Alt f (a -> b) -> Alt f a -> Alt f b # liftA2 :: (a -> b -> c) -> Alt f a -> Alt f b -> Alt f c # (>) :: Alt f a -> Alt f b -> Alt f b # (<*) :: Alt f a -> Alt f b -> Alt f a #
Alternative f => Alternative (Alt f)
Instance details Defined in Data.Semigroup.Internal Methods empty :: Alt f a # (<\|>) :: Alt f a -> Alt f a -> Alt f a # some :: Alt f a -> Alt f [a] # many :: Alt f a -> Alt f [a] #
Contravariant f => Contravariant (Alt f)
Instance details Defined in Data.Functor.Contravariant Methods contramap :: (a -> b) -> Alt f b -> Alt f a # (>$) :: b -> Alt f b -> Alt f a #
MonadPlus f => MonadPlus (Alt f)
Instance details Defined in Data.Semigroup.Internal Methods mzero :: Alt f a # mplus :: Alt f a -> Alt f a -> Alt f a #
MonadZip f => MonadZip (Alt f)	Since: base-4.8.0.0
Instance details Defined in Control.Monad.Zip Methods mzip :: Alt f a -> Alt f b -> Alt f (a, b) # mzipWith :: (a -> b -> c) -> Alt f a -> Alt f b -> Alt f c # munzip :: Alt f (a, b) -> (Alt f a, Alt f b) #
Divisible f => Divisible (Alt f)
Instance details Defined in Data.Functor.Contravariant.Divisible Methods divide :: (a -> (b, c)) -> Alt f b -> Alt f c -> Alt f a # conquer :: Alt f a #
Decidable f => Decidable (Alt f)
Instance details Defined in Data.Functor.Contravariant.Divisible Methods lose :: (a -> Void) -> Alt f a # choose :: (a -> Either b c) -> Alt f b -> Alt f c -> Alt f a #
Apply f => Apply (Alt f)
Instance details Defined in Data.Functor.Bind.Class Methods (<.>) :: Alt f (a -> b) -> Alt f a -> Alt f b # (.>) :: Alt f a -> Alt f b -> Alt f b # (<.) :: Alt f a -> Alt f b -> Alt f a # liftF2 :: (a -> b -> c) -> Alt f a -> Alt f b -> Alt f c #
Traversable1 f => Traversable1 (Alt f)
Instance details Defined in Data.Semigroup.Traversable.Class Methods traverse1 :: Apply f0 => (a -> f0 b) -> Alt f a -> f0 (Alt f b) # sequence1 :: Apply f0 => Alt f (f0 b) -> f0 (Alt f b) #
Foldable1 f => Foldable1 (Alt f)
Instance details Defined in Data.Semigroup.Foldable.Class Methods fold1 :: Semigroup m => Alt f m -> m # foldMap1 :: Semigroup m => (a -> m) -> Alt f a -> m # toNonEmpty :: Alt f a -> NonEmpty a #
Bind f => Bind (Alt f)
Instance details Defined in Data.Functor.Bind.Class Methods (>>-) :: Alt f a -> (a -> Alt f b) -> Alt f b # join :: Alt f (Alt f a) -> Alt f a #
Extend f => Extend (Alt f)
Instance details Defined in Data.Functor.Extend Methods duplicated :: Alt f a -> Alt f (Alt f a) # extended :: (Alt f a -> b) -> Alt f a -> Alt f b #
Enum (f a) => Enum (Alt f a)
Instance details Defined in Data.Semigroup.Internal Methods succ :: Alt f a -> Alt f a # pred :: Alt f a -> Alt f a # toEnum :: Int -> Alt f a # fromEnum :: Alt f a -> Int # enumFrom :: Alt f a -> [Alt f a] # enumFromThen :: Alt f a -> Alt f a -> [Alt f a] # enumFromTo :: Alt f a -> Alt f a -> [Alt f a] # enumFromThenTo :: Alt f a -> Alt f a -> Alt f a -> [Alt f a] #
Eq (f a) => Eq (Alt f a)
Instance details Defined in Data.Semigroup.Internal Methods (==) :: Alt f a -> Alt f a -> Bool # (/=) :: Alt f a -> Alt f a -> Bool #
(Data (f a), Data a, Typeable f) => Data (Alt f a)	Since: base-4.8.0.0
Instance details Defined in Data.Data Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Alt f a -> c (Alt f a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Alt f a) # toConstr :: Alt f a -> Constr # dataTypeOf :: Alt f a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Alt f a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Alt f a)) # gmapT :: (forall b. Data b => b -> b) -> Alt f a -> Alt f a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Alt f a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Alt f a -> r # gmapQ :: (forall d. Data d => d -> u) -> Alt f a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Alt f a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Alt f a -> m (Alt f a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Alt f a -> m (Alt f a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Alt f a -> m (Alt f a) #
Num (f a) => Num (Alt f a)
Instance details Defined in Data.Semigroup.Internal Methods (+) :: Alt f a -> Alt f a -> Alt f a # (-) :: Alt f a -> Alt f a -> Alt f a # (*) :: Alt f a -> Alt f a -> Alt f a # negate :: Alt f a -> Alt f a # abs :: Alt f a -> Alt f a # signum :: Alt f a -> Alt f a # fromInteger :: Integer -> Alt f a #
Ord (f a) => Ord (Alt f a)
Instance details Defined in Data.Semigroup.Internal Methods compare :: Alt f a -> Alt f a -> Ordering # (<) :: Alt f a -> Alt f a -> Bool # (<=) :: Alt f a -> Alt f a -> Bool # (>) :: Alt f a -> Alt f a -> Bool # (>=) :: Alt f a -> Alt f a -> Bool # max :: Alt f a -> Alt f a -> Alt f a # min :: Alt f a -> Alt f a -> Alt f a #
Read (f a) => Read (Alt f a)
Instance details Defined in Data.Semigroup.Internal Methods readsPrec :: Int -> ReadS (Alt f a) # readList :: ReadS [Alt f a] # readPrec :: ReadPrec (Alt f a) # readListPrec :: ReadPrec [Alt f a] #
Show (f a) => Show (Alt f a)
Instance details Defined in Data.Semigroup.Internal Methods showsPrec :: Int -> Alt f a -> ShowS # show :: Alt f a -> String # showList :: [Alt f a] -> ShowS #
Generic (Alt f a)
Instance details Defined in Data.Semigroup.Internal Associated Types type Rep (Alt f a) :: * -> * # Methods from :: Alt f a -> Rep (Alt f a) x # to :: Rep (Alt f a) x -> Alt f a #
Alternative f => Semigroup (Alt f a)	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup.Internal Methods (<>) :: Alt f a -> Alt f a -> Alt f a # sconcat :: NonEmpty (Alt f a) -> Alt f a # stimes :: Integral b => b -> Alt f a -> Alt f a #
Alternative f => Monoid (Alt f a)	Since: base-4.8.0.0
Instance details Defined in Data.Semigroup.Internal Methods mempty :: Alt f a # mappend :: Alt f a -> Alt f a -> Alt f a # mconcat :: [Alt f a] -> Alt f a #
Wrapped (Alt f a)
Instance details Defined in Control.Lens.Wrapped Associated Types type Unwrapped (Alt f a) :: * # Methods _Wrapped' :: Iso' (Alt f a) (Unwrapped (Alt f a)) #
Serialise (f a) => Serialise (Alt f a)	Since: serialise-0.2.0.0
Instance details Defined in Codec.Serialise.Class Methods encode :: Alt f a -> Encoding # decode :: Decoder s (Alt f a) # encodeList :: [Alt f a] -> Encoding # decodeList :: Decoder s [Alt f a] #
t ~ Alt g b => Rewrapped (Alt f a) t
Instance details Defined in Control.Lens.Wrapped
type Rep1 (Alt f :: k -> *)
Instance details Defined in Data.Semigroup.Internal type Rep1 (Alt f :: k -> *) = D1 (MetaData "Alt" "Data.Semigroup.Internal" "base" True) (C1 (MetaCons "Alt" PrefixI True) (S1 (MetaSel (Just "getAlt") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec1 f)))
type Rep (Alt f a)
Instance details Defined in Data.Semigroup.Internal type Rep (Alt f a) = D1 (MetaData "Alt" "Data.Semigroup.Internal" "base" True) (C1 (MetaCons "Alt" PrefixI True) (S1 (MetaSel (Just "getAlt") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (f a))))
type Unwrapped (Alt f a)
Instance details Defined in Control.Lens.Wrapped type Unwrapped (Alt f a) = f a

Free applicative

data Ap (f :: * -> *) a where #

The free Applicative for a Functor f.

Constructors

Pure :: Ap f a
Ap :: Ap f a

Instances

Functor (Ap f)
Instance details Defined in Control.Applicative.Free Methods fmap :: (a -> b) -> Ap f a -> Ap f b # (<$) :: a -> Ap f b -> Ap f a #
Applicative (Ap f)
Instance details Defined in Control.Applicative.Free 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 #
Comonad f => Comonad (Ap f)
Instance details Defined in Control.Applicative.Free Methods extract :: Ap f a -> a # duplicate :: Ap f a -> Ap f (Ap f a) # extend :: (Ap f a -> b) -> Ap f a -> Ap f b #
Apply (Ap f)
Instance details Defined in Control.Applicative.Free Methods (<.>) :: Ap f (a -> b) -> Ap f a -> Ap f b # (.>) :: Ap f a -> Ap f b -> Ap f b # (<.) :: Ap f a -> Ap f b -> Ap f a # liftF2 :: (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c #

runAp :: Applicative g => (forall x. f x -> g x) -> Ap f a -> g a #

Given a natural transformation from f to g, this gives a canonical monoidal natural transformation from Ap f to g.

runAp t == retractApp . hoistApp t

runAp_ :: Monoid m => (forall a. f a -> m) -> Ap f b -> m #

Perform a monoidal analysis over free applicative value.

Example:

count :: Ap f a -> Int
count = getSum . runAp_ (\_ -> Sum 1)

liftAp :: f a -> Ap f a #

A version of lift that can be used with just a Functor for f.

iterAp :: Functor g => (g a -> a) -> Ap g a -> a #

Tear down a free Applicative using iteration.

hoistAp :: (forall a. f a -> g a) -> Ap f b -> Ap g b #

Given a natural transformation from f to g this gives a monoidal natural transformation from Ap f to Ap g.

retractAp :: Applicative f => Ap f a -> f a #

Interprets the free applicative functor over f using the semantics for pure and <*> given by the Applicative instance for f.

retractApp == runAp id