ghc-8.2.2: The GHC API

Safe HaskellNone
LanguageHaskell2010

MonadUtils

Description

Utilities related to Monad and Applicative classes Mostly for backwards compatibility.

Synopsis

Documentation

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:

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

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

(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.

(*>) :: 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: 2.1

Methods

pure :: a -> [a] #

(<*>) :: [a -> b] -> [a] -> [b] #

liftA2 :: (a -> b -> c) -> [a] -> [b] -> [c] #

(*>) :: [a] -> [b] -> [b] #

(<*) :: [a] -> [b] -> [a] #

Applicative Maybe

Since: 2.1

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: 2.1

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: 4.9.0.0

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 

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 P

Since: 4.5.0.0

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 Complex

Since: 4.9.0.0

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: 4.9.0.0

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: 4.9.0.0

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: 4.9.0.0

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: 4.9.0.0

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: 4.9.0.0

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 NonEmpty

Since: 4.9.0.0

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 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: 2.1

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: 4.8.0.0

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: 4.8.0.0

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 Dual

Since: 4.8.0.0

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: 4.8.0.0

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: 4.8.0.0

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 First 

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 

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 ReadPrec

Since: 4.6.0.0

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: 4.6.0.0

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 PutM 

Methods

pure :: a -> PutM a #

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

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

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

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

Applicative Get 

Methods

pure :: a -> Get a #

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

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

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

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

Applicative Put 

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 

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 

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 VM 

Methods

pure :: a -> VM a #

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

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

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

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

Applicative SimpleUniqueMonad 
Applicative Capability 

Methods

pure :: a -> Capability a #

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

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

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

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

Applicative Pair # 

Methods

pure :: a -> Pair a #

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

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

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

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

Applicative UniqSM # 

Methods

pure :: a -> UniqSM a #

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

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

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

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

Applicative P # 

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 PD # 

Methods

pure :: a -> PD a #

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

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

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

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

Applicative UnifyResultM # 
Applicative LlvmM # 

Methods

pure :: a -> LlvmM a #

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

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

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

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

Applicative FCode # 

Methods

pure :: a -> FCode a #

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

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

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

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

Applicative CmmParse # 

Methods

pure :: a -> CmmParse a #

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

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

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

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

Applicative Hsc # 

Methods

pure :: a -> Hsc a #

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

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

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

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

Applicative TcPluginM # 

Methods

pure :: a -> TcPluginM a #

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

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

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

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

Applicative CompPipeline # 
Applicative Ghc # 

Methods

pure :: a -> Ghc a #

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

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

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

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

Applicative CoreM # 

Methods

pure :: a -> CoreM a #

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

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

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

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

Applicative SimplM # 

Methods

pure :: a -> SimplM a #

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

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

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

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

Applicative CpsRn # 

Methods

pure :: a -> CpsRn a #

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

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

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

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

Applicative OccCheckResult # 
Applicative TcS # 

Methods

pure :: a -> TcS a #

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

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

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

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

Applicative VM # 

Methods

pure :: a -> VM a #

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

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

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

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

Applicative NatM # 

Methods

pure :: a -> NatM a #

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

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

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

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

Applicative (Either e)

Since: 3.0

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: 4.9.0.0

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, Strings concatenate:

("hello ", (+15)) <*> ("world!", 2002)
("hello world!",2017)

Since: 2.1

Methods

pure :: a -> (a, a) #

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

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

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

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

Applicative (ST s)

Since: 4.4.0.0

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 #

Monad m => Applicative (WrappedMonad m)

Since: 2.1

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: 4.6.0.0

Methods

pure :: a -> ArrowMonad a a #

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

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

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

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

Applicative (Proxy *)

Since: 4.7.0.0

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 (SetM s) 

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 (State s) 

Methods

pure :: a -> State s a #

(<*>) :: State s (a -> b) -> State s a -> State s b #

liftA2 :: (a -> b -> c) -> State s a -> State s b -> State s c #

(*>) :: State s a -> State s b -> State s b #

(<*) :: State s a -> State s b -> State s a #

Monad m => Applicative (CheckingFuelMonad m) 
Monad m => Applicative (InfiniteFuelMonad m) 
Monad m => Applicative (UniqueMonadT m) 

Methods

pure :: a -> UniqueMonadT m a #

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

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

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

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

(Functor m, Monad m) => Applicative (MaybeT m) 

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 (ListT f) # 

Methods

pure :: a -> ListT f a #

(<*>) :: ListT f (a -> b) -> ListT f a -> ListT f b #

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

(*>) :: ListT f a -> ListT f b -> ListT f b #

(<*) :: ListT f a -> ListT f b -> ListT f a #

Applicative (State s) # 

Methods

pure :: a -> State s a #

(<*>) :: State s (a -> b) -> State s a -> State s b #

liftA2 :: (a -> b -> c) -> State s a -> State s b -> State s c #

(*>) :: State s a -> State s b -> State s b #

(<*) :: State s a -> State s b -> State s a #

Applicative (MaybeErr err) # 

Methods

pure :: a -> MaybeErr err a #

(<*>) :: MaybeErr err (a -> b) -> MaybeErr err a -> MaybeErr err b #

liftA2 :: (a -> b -> c) -> MaybeErr err a -> MaybeErr err b -> MaybeErr err c #

(*>) :: MaybeErr err a -> MaybeErr err b -> MaybeErr err b #

(<*) :: MaybeErr err a -> MaybeErr err b -> MaybeErr err a #

Applicative (CmdLineP s) # 

Methods

pure :: a -> CmdLineP s a #

(<*>) :: CmdLineP s (a -> b) -> CmdLineP s a -> CmdLineP s b #

liftA2 :: (a -> b -> c) -> CmdLineP s a -> CmdLineP s b -> CmdLineP s c #

(*>) :: CmdLineP s a -> CmdLineP s b -> CmdLineP s b #

(<*) :: CmdLineP s a -> CmdLineP s b -> CmdLineP s a #

Monad m => Applicative (EwM m) # 

Methods

pure :: a -> EwM m a #

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

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

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

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

Applicative (IOEnv m) # 

Methods

pure :: a -> IOEnv m a #

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

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

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

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

Applicative (RegM freeRegs) # 

Methods

pure :: a -> RegM freeRegs a #

(<*>) :: RegM freeRegs (a -> b) -> RegM freeRegs a -> RegM freeRegs b #

liftA2 :: (a -> b -> c) -> RegM freeRegs a -> RegM freeRegs b -> RegM freeRegs c #

(*>) :: RegM freeRegs a -> RegM freeRegs b -> RegM freeRegs b #

(<*) :: RegM freeRegs a -> RegM freeRegs b -> RegM freeRegs a #

Applicative m => Applicative (GhcT m) # 

Methods

pure :: a -> GhcT m a #

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

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

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

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

Applicative f => Applicative (Rec1 * f)

Since: 4.9.0.0

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 #

Arrow a => Applicative (WrappedArrow a b)

Since: 2.1

Methods

pure :: a -> WrappedArrow a b a #

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

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

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

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

Monoid m => Applicative (Const * m)

Since: 2.0.1

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) 

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 #

(Applicative f, Monad f) => Applicative (WhenMissing f x)

Equivalent to ReaderT k (ReaderT x (MaybeT f)).

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 #

(Monoid w, Applicative m) => Applicative (WriterT w m) 

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 #

(Functor m, Monad m) => Applicative (StateT s m) 

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) 

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 (ExceptT e m) 

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 (Stream m a) # 

Methods

pure :: a -> Stream m a a #

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

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

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

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

Applicative ((->) LiftedRep LiftedRep a)

Since: 2.1

Methods

pure :: a -> (LiftedRep -> LiftedRep) a a #

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

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

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

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

(Applicative f, Applicative g) => Applicative ((:*:) * f g)

Since: 4.9.0.0

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 #

(Monad f, Applicative f) => Applicative (WhenMatched f x y)

Equivalent to ReaderT Key (ReaderT x (ReaderT y (MaybeT f)))

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)) .

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 m => Applicative (ReaderT * r m) 

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 #

Applicative f => Applicative (M1 * i c f)

Since: 4.9.0.0

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 -> c) -> M1 * i c f a -> M1 * i c f b -> M1 * i c f c #

(*>) :: 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: 4.9.0.0

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 #

(Monad f, Applicative f) => Applicative (WhenMatched f k x y)

Equivalent to ReaderT k (ReaderT x (ReaderT y (MaybeT f)))

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 #

(<$>) :: Functor f => (a -> b) -> f a -> f b infixl 4 #

An infix synonym for fmap.

The name of this operator is an allusion to $. Note the similarities between their types:

 ($)  ::              (a -> b) ->   a ->   b
(<$>) :: Functor f => (a -> b) -> f a -> f b

Whereas $ is function application, <$> is function application lifted over a Functor.

Examples

Convert from a Maybe Int to a Maybe String using show:

>>> show <$> Nothing
Nothing
>>> show <$> Just 3
Just "3"

Convert from an Either Int Int to an Either Int String using show:

>>> show <$> Left 17
Left 17
>>> show <$> Right 17
Right "17"

Double each element of a list:

>>> (*2) <$> [1,2,3]
[2,4,6]

Apply even to the second element of a pair:

>>> even <$> (2,2)
(2,True)

class Monad m => MonadFix (m :: * -> *) where #

Monads having fixed points with a 'knot-tying' semantics. Instances of MonadFix should satisfy the following laws:

purity
mfix (return . h) = return (fix h)
left shrinking (or tightening)
mfix (\x -> a >>= \y -> f x y) = a >>= \y -> mfix (\x -> f x y)
sliding
mfix (liftM h . f) = liftM h (mfix (f . h)), for strict h.
nesting
mfix (\x -> mfix (\y -> f x y)) = mfix (\x -> f x x)

This class is used in the translation of the recursive do notation supported by GHC and Hugs.

Minimal complete definition

mfix

Methods

mfix :: (a -> m a) -> m a #

The fixed point of a monadic computation. mfix f executes the action f only once, with the eventual output fed back as the input. Hence f should not be strict, for then mfix f would diverge.

Instances

MonadFix []

Since: 2.1

Methods

mfix :: (a -> [a]) -> [a] #

MonadFix Maybe

Since: 2.1

Methods

mfix :: (a -> Maybe a) -> Maybe a #

MonadFix IO

Since: 2.1

Methods

mfix :: (a -> IO a) -> IO a #

MonadFix Par1

Since: 4.9.0.0

Methods

mfix :: (a -> Par1 a) -> Par1 a #

MonadFix Min

Since: 4.9.0.0

Methods

mfix :: (a -> Min a) -> Min a #

MonadFix Max

Since: 4.9.0.0

Methods

mfix :: (a -> Max a) -> Max a #

MonadFix First

Since: 4.9.0.0

Methods

mfix :: (a -> First a) -> First a #

MonadFix Last

Since: 4.9.0.0

Methods

mfix :: (a -> Last a) -> Last a #

MonadFix Option

Since: 4.9.0.0

Methods

mfix :: (a -> Option a) -> Option a #

MonadFix NonEmpty

Since: 4.9.0.0

Methods

mfix :: (a -> NonEmpty a) -> NonEmpty a #

MonadFix Identity

Since: 4.8.0.0

Methods

mfix :: (a -> Identity a) -> Identity a #

MonadFix Dual

Since: 4.8.0.0

Methods

mfix :: (a -> Dual a) -> Dual a #

MonadFix Sum

Since: 4.8.0.0

Methods

mfix :: (a -> Sum a) -> Sum a #

MonadFix Product

Since: 4.8.0.0

Methods

mfix :: (a -> Product a) -> Product a #

MonadFix First

Since: 4.8.0.0

Methods

mfix :: (a -> First a) -> First a #

MonadFix Last

Since: 4.8.0.0

Methods

mfix :: (a -> Last a) -> Last a #

MonadFix UniqSM # 

Methods

mfix :: (a -> UniqSM a) -> UniqSM a #

MonadFix Ghc # 

Methods

mfix :: (a -> Ghc a) -> Ghc a #

MonadFix (Either e)

Since: 4.3.0.0

Methods

mfix :: (a -> Either e a) -> Either e a #

MonadFix (ST s)

Since: 2.1

Methods

mfix :: (a -> ST s a) -> ST s a #

MonadFix m => MonadFix (MaybeT m) 

Methods

mfix :: (a -> MaybeT m a) -> MaybeT m a #

MonadFix f => MonadFix (Rec1 * f)

Since: 4.9.0.0

Methods

mfix :: (a -> Rec1 * f a) -> Rec1 * f a #

MonadFix f => MonadFix (Alt * f)

Since: 4.8.0.0

Methods

mfix :: (a -> Alt * f a) -> Alt * f a #

(Monoid w, MonadFix m) => MonadFix (WriterT w m) 

Methods

mfix :: (a -> WriterT w m a) -> WriterT w m a #

MonadFix m => MonadFix (StateT s m) 

Methods

mfix :: (a -> StateT s m a) -> StateT s m a #

MonadFix m => MonadFix (StateT s m) 

Methods

mfix :: (a -> StateT s m a) -> StateT s m a #

MonadFix m => MonadFix (ExceptT e m) 

Methods

mfix :: (a -> ExceptT e m a) -> ExceptT e m a #

MonadFix ((->) LiftedRep LiftedRep r)

Since: 2.1

Methods

mfix :: (a -> (LiftedRep -> LiftedRep) r a) -> (LiftedRep -> LiftedRep) r a #

(MonadFix f, MonadFix g) => MonadFix ((:*:) * f g)

Since: 4.9.0.0

Methods

mfix :: (a -> (* :*: f) g a) -> (* :*: f) g a #

MonadFix m => MonadFix (ReaderT * r m) 

Methods

mfix :: (a -> ReaderT * r m a) -> ReaderT * r m a #

MonadFix f => MonadFix (M1 * i c f)

Since: 4.9.0.0

Methods

mfix :: (a -> M1 * i c f a) -> M1 * i c f a #

class Monad m => MonadIO (m :: * -> *) where #

Monads in which IO computations may be embedded. Any monad built by applying a sequence of monad transformers to the IO monad will be an instance of this class.

Instances should satisfy the following laws, which state that liftIO is a transformer of monads:

Minimal complete definition

liftIO

Methods

liftIO :: IO a -> m a #

Lift a computation from the IO monad.

Instances

MonadIO IO

Since: 4.9.0.0

Methods

liftIO :: IO a -> IO a #

MonadIO Hsc # 

Methods

liftIO :: IO a -> Hsc a #

MonadIO CompPipeline # 

Methods

liftIO :: IO a -> CompPipeline a #

MonadIO Ghc # 

Methods

liftIO :: IO a -> Ghc a #

MonadIO CoreM # 

Methods

liftIO :: IO a -> CoreM a #

MonadIO SimplM # 

Methods

liftIO :: IO a -> SimplM a #

MonadIO VM # 

Methods

liftIO :: IO a -> VM a #

MonadIO m => MonadIO (MaybeT m) 

Methods

liftIO :: IO a -> MaybeT m a #

MonadIO (IOEnv env) # 

Methods

liftIO :: IO a -> IOEnv env a #

MonadIO m => MonadIO (GhcT m) # 

Methods

liftIO :: IO a -> GhcT m a #

(Monoid w, MonadIO m) => MonadIO (WriterT w m) 

Methods

liftIO :: IO a -> WriterT w m a #

MonadIO m => MonadIO (StateT s m) 

Methods

liftIO :: IO a -> StateT s m a #

MonadIO m => MonadIO (StateT s m) 

Methods

liftIO :: IO a -> StateT s m a #

MonadIO m => MonadIO (ExceptT e m) 

Methods

liftIO :: IO a -> ExceptT e m a #

MonadIO m => MonadIO (ReaderT * r m) 

Methods

liftIO :: IO a -> ReaderT * r m a #

liftIO1 :: MonadIO m => (a -> IO b) -> a -> m b Source #

Lift an IO operation with 1 argument into another monad

liftIO2 :: MonadIO m => (a -> b -> IO c) -> a -> b -> m c Source #

Lift an IO operation with 2 arguments into another monad

liftIO3 :: MonadIO m => (a -> b -> c -> IO d) -> a -> b -> c -> m d Source #

Lift an IO operation with 3 arguments into another monad

liftIO4 :: MonadIO m => (a -> b -> c -> d -> IO e) -> a -> b -> c -> d -> m e Source #

Lift an IO operation with 4 arguments into another monad

zipWith3M :: Monad m => (a -> b -> c -> m d) -> [a] -> [b] -> [c] -> m [d] Source #

zipWith3M_ :: Monad m => (a -> b -> c -> m d) -> [a] -> [b] -> [c] -> m () Source #

zipWith4M :: Monad m => (a -> b -> c -> d -> m e) -> [a] -> [b] -> [c] -> [d] -> m [e] Source #

zipWithAndUnzipM :: Monad m => (a -> b -> m (c, d)) -> [a] -> [b] -> m ([c], [d]) Source #

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

The mapAndUnzipM function maps its first argument over a list, returning the result as a pair of lists. This function is mainly used with complicated data structures or a state-transforming monad.

mapAndUnzip3M :: Monad m => (a -> m (b, c, d)) -> [a] -> m ([b], [c], [d]) Source #

mapAndUnzipM for triples

mapAndUnzip4M :: Monad m => (a -> m (b, c, d, e)) -> [a] -> m ([b], [c], [d], [e]) Source #

mapAndUnzip5M :: Monad m => (a -> m (b, c, d, e, f)) -> [a] -> m ([b], [c], [d], [e], [f]) Source #

mapAccumLM Source #

Arguments

:: Monad m 
=> (acc -> x -> m (acc, y))

combining function

-> acc

initial state

-> [x]

inputs

-> m (acc, [y])

final state, outputs

Monadic version of mapAccumL

mapSndM :: Monad m => (b -> m c) -> [(a, b)] -> m [(a, c)] Source #

Monadic version of mapSnd

concatMapM :: Monad m => (a -> m [b]) -> [a] -> m [b] Source #

Monadic version of concatMap

mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b] Source #

Monadic version of mapMaybe

fmapMaybeM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b) Source #

Monadic version of fmap

fmapEitherM :: Monad m => (a -> m b) -> (c -> m d) -> Either a c -> m (Either b d) Source #

Monadic version of fmap

anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool Source #

Monadic version of any, aborts the computation at the first True value

allM :: Monad m => (a -> m Bool) -> [a] -> m Bool Source #

Monad version of all, aborts the computation at the first False value

orM :: Monad m => m Bool -> m Bool -> m Bool Source #

Monadic version of or

foldlM :: Monad m => (a -> b -> m a) -> a -> [b] -> m a Source #

Monadic version of foldl

foldlM_ :: Monad m => (a -> b -> m a) -> a -> [b] -> m () Source #

Monadic version of foldl that discards its result

foldrM :: Monad m => (b -> a -> m a) -> a -> [b] -> m a Source #

Monadic version of foldr

maybeMapM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b) Source #

Monadic version of fmap specialised for Maybe

whenM :: Monad m => m Bool -> m () -> m () Source #

Monadic version of when, taking the condition in the monad

unlessM :: Monad m => m Bool -> m () -> m () Source #

Monadic version of unless, taking the condition in the monad